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Background and Objective: The association of hypouricemia and hypercalciuria is rare. In 1974 a new syndrome named Hypouricemia with hypercalciuria and decreased bone density was described. Afterwards, some cases with such association were published in which the fractional excretion of urate was higher than 20ml/100ml FGR. We have analyzed a series of children who were diagnosed with hypouricemia and hypercalciuria and who were monitored. The aim of this study was to determine whether our patients could be affected by the aforementioned syndrome or be carriers of a variant of idiopathic hypercalciuria., Patients and Methods: Retrospective longitudinal study in which the medical records of eight patients (5V, 3M) diagnosed with hypouricemia and hypercalciuria in childhood. Clinical features at diagnosis, ultrasound and densitometric findings and selected biochemical variables were noted, with special emphasis on renal tubular handling of urate. Results were compared with 36 children with idiopathic hypercalciuria without hypouricemia (14V, 22M)., Results: In the hypouricemia group baseline urate levels were 1.9 (0.3) mg/dl (range: 1.5-2) and first day urine calcium/creatinine ratio 0.27 (0.05) mg/mg (range: 0.23-0.31). In all cases fractional urate excretion was less than 20ml/100ml FGR. The z-DMO values were less than -1 in 4/8 cases. At the last follow-up only three cases still had an elevated calcium/creatinine ratio and in all of them the urates levels was greater than 2mg/dl. The z-DMO value had improved in five cases and worsened in three others. In relation to the group without hypouricemia, no differences were observed between the various parameters studied including the z-DMO value, with the exception of fractional excretion and tubular urate reabsorption although plasmatic uric acid levels were still significantly lower., Conclusion: Our patients with hypercalciuria and hypouricemia would be affected by a variant of idiopathic hypercalciuria in which, due to an unknown cause, the proximal tubular reabsorption of urate is modestly reduced and improves over time. Hypouricemia with hypercalciuria and decreased bone density may not be a specific entity., (Copyright © 2024. Published by Elsevier España, S.L.U.)

In the present work, we present an overview of the contents of the communications presented at the Second National Congress of Paediatrics, held in San Sebastian in 1923, on the occasion of the 100th year anniversary. The problem of infant mortality stands out as a common thread, which in those years was very high in Spain and was a concern of politicians, intellectuals and the medical profession. It is worth noting that some of the proposals and concerns of the paediatricians who attended that congress continue to be relevant today., (Copyright © 2023 Asociación Española de Pediatría. Published by Elsevier España, S.L.U. All rights reserved.)

Background: Fractional tubular reabsorption of phosphate (TRP) has been used for over 60 years to establish the existence of renal phosphate loss. It is a parameter of corrected volume per decilitre of glomerular filtration rate (GFR). Later, a mass parameter per dl GFR called TP/GFR (tubular PO 4 reabsorption per dl GFR) was devised which some authors have sought to substitute for TRP. The aim of the present work is to attempt to demonstrate that TRP and TP/GFR are similar parameters and, in certain aspects, TRP is more effective for diagnosis., Methods: Data were gathered on the metabolism of phosphate corresponding to a group of healthy children without hypophosphatemia (n = 47), a group of patients with idiopathic hypercalciuria (n = 27), and ten patients diagnosed with X-linked hypophosphatemia (XLH). The TRP, the TP/GFR, and the percent tubular reabsorption of phosphate were calculated., Results: All the patients with XLH presented TRP values lower than 95 ml/dl GFR and of TP/GFR equal to or lower than 2.8 mg/dl GFR. In the total sample, a direct correlation was observed between TRP and TP/GFR (r = 0.65; p = 0.01). The TRP and the percent tubular reabsorption of phosphate values were the same in the three groups (r = 1; p = 0.01)., Conclusions: TRP and TP/GFR are similar parameters. TRP is more effective than TP/GFR given that in renal hypophosphatemia it is always below 95% and above 95% in reduced phosphatemia and normal kidney proximal tubular function. There is no solid reason for using TP/GFR rather than TRP. A higher resolution version of the Graphical abstract is available as Supplementary information., (© 2023. The Author(s), under exclusive licence to International Pediatric Nephrology Association.)

Objectives: Reflux nephropathy is a radiologic condition commonly used to express the existence of renal morphological lesions in patients who have or had vesicoureteral reflux (VUR). This morphological concept is used based on the image data collected, without conducting basic complementary renal function studies. The present study was designed to demonstrate that patients with active VUR present different functional renal alterations from those shown by patients with disappeared VUR., Methods: Longitudinal descriptive retrospective analysis including 89 children (46M, 43F) with VUR diagnosis through a standard voiding cystourethrogram (VCUG). The basic renal function tests collected were the maximum urinary osmolality (UOsm) and the urinary albumin/creatinine and NAG/creatinine ratios. The data collected corresponded to two moments, when VUR was diagnosed and when it had already disappeared., Results: Quantitative differences were verified in the three functional parameters when comparing those corresponding to both moments of the study. In the qualitative analysis, in relation to the intensity of the VUR, differences were observed in UOsm at diagnosis and in the albumin/creatinine ratio once the VUR had cured. At this last moment, a significant increase in the albumin/creatinine ratio was observed in patients with loss of renal parenchyma in relation to those without residual morphological lesions., Conclusions: Concentrating ability defect is the most frequent finding in children with active reflux (true reflux nephropathy), whereas the most frequent functional disturbance found, once VUR has cured, is an increase in urinary albumin excretion, related to parenchymal damage. The term dysplastic-scarring nephropathy, could be more appropriate for patients with residual morphological lesions and impaired renal function, once VUR is cured., (Copyright © 2021 Asociación Española de Pediatría. Published by Elsevier España, S.L.U. All rights reserved.)

Gout is recurrent inflammatory arthritis caused by the deposition of monosodium urate crystals in the joints. The risk factors that predispose to suffering from gout include non-modifiable factors such as gender, age, ethnicity and genetics, and modifiable factors such as diet and lifestyle. It has been shown that the heritability of uric acid levels in the blood is greater than 30%, which indicates that genetics play a key role in these levels. Hyperuricaemia is often a consequence of reduced renal urate excretion since more than 70% is excreted by the kidneys, mainly through the proximal tubule. The mechanisms that explain that hyperuricaemia associated with reduced renal urate excretion is, to a large extent, a proximal renal tubular disorder, have begun to be understood following the identification of two genes that encode the URAT1 and GLUT9 transporters. When they are carriers of loss-of-function mutations, they explain the two known variants of renal tubular hypouricaemia. Some polymorphisms in these genes may have an opposite gain-of-function effect, with a consequent increase in urate reabsorption. Conversely, loss-of-function polymorphisms in other genes that encode transporters involved in urate excretion (ABCG2, ABCC4) can lead to hyperuricaemia. Genome-wide association study (GWAS) methods have made it possible to locate new gout-related loci associated with reduced renal urate excretion (NIPAL1, FAM35A)., (Copyright © 2022. Published by Elsevier España, S.L.U.)

Gout is recurrent inflammatory arthritis caused by the deposition of monosodium urate crystals in the joints. The risk factors that predispose to suffering from gout include non-modifiable factors such as gender, age, ethnicity and genetics, and modifiable factors such as diet and lifestyle. It has been shown that the heritability of uric acid levels in the blood is greater than 30%, which indicates that genetics play a key role in these levels. Hyperuricaemia is often a consequence of reduced renal urate excretion since more than 70% is excreted by the kidneys, mainly through the proximal tubule. The mechanisms that explain that hyperuricaemia associated with reduced renal urate excretion is, to a large extent, a proximal renal tubular disorder, have begun to be understood following the identification of two genes that encode the URAT1 and GLUT9 transporters. When they are carriers of loss-of-function mutations, they explain the two known variants of renal tubular hypouricaemia. Some polymorphisms in these genes may have an opposite gain-of-function effect, with a consequent increase in urate reabsorption. Conversely, loss-of-function polymorphisms in other genes that encode transporters involved in urate excretion (ABCG2, ABCC4) can lead to hyperuricaemia. Genome-wide association study (GWAS) methods have made it possible to locate new gout-related loci associated with reduced renal urate excretion (NIPAL1, FAM35A)., (Copyright © 2021 Sociedad Española de Nefrología. Published by Elsevier España, S.L.U. All rights reserved.)

Objectives: Reflux nephropathy is a radiologic condition commonly used to express the existence of renal morphological lesions in patients who have or had vesicoureteral reflux (VUR). This morphological concept is used based on the image data collected, without conducting basic complementary renal function studies. The present study was designed to demonstrate that patients with active VUR present different functional renal alterations from those shown by patients with disappeared VUR., Patients and Methods: Longitudinal descriptive retrospective analysis including 89 children (46M, 43F) with VUR diagnosis through a standard voiding cystourethrogram (VCUG). The basic renal function tests collected were the maximum urinary osmolality (UOsm) and the urinary albumin/creatinine and NAG/creatinine ratios. The data collected corresponded to two moments, when VUR was diagnosed and when it had already disappeared., Results: Quantitative differences were verified in the three functional parameters when comparing those corresponding to both moments of the study. In the qualitative analysis, in relation to the intensity of the VUR, differences were observed in UOsm at diagnosis and in the albumin/creatinine ratio once the VUR had cured. At this last moment, a significant increase in the albumin/creatinine ratio was observed in patients with loss of renal parenchyma in relation to those without residual morphological lesions., Conclusions: Concentrating ability defect is the most frequent finding in children with active reflux (true reflux nephropathy), whereas the most frequent functional disturbance found, once VUR has cured, is an increase in urinary albumin excretion, related to parenchymal damage. The term dysplastic-scarring nephropathy, could be more appropriate for patients with residual morphological lesions and impaired renal function, once VUR is cured., (Copyright © 2021 Asociación Española de Pediatría. Publicado por Elsevier España, S.L.U. All rights reserved.)

Introduction: Split renal function measured in a diuretic renogram is the most popular tool in initial assessment and follow-up of patients with ureteropelvic junction obstruction (UPJO). This study aims to evaluate the use of maximum urinary osmolality after desmopressin administration (DDAVP) to detect renal dysfunction., Patients and Methods: 56 children (33 males, 23 females) diagnosed with UPJO underwent quantification of the maximum urinary osmolality (UOsm) at diagnosis. 41 of these children (28 males, 13 females) underwent surgery for UPJO and quantification of the UOsm before and after the surgical intervention (six to 18 months postoperatively) and were included in this longitudinal study., Results and Discussion: At diagnosis, UOsm measured after desmopressin administration was abnormal in 64% of patients. After surgical intervention, this rate decreased to 53%. At initial assessment, high creatinine levels were found in 32% of infants younger than one year of age. Albumin/Cr and NAG/Cr ratios were elevated in 12% and 7% of cases, respectively. After surgical intervention, an improvement in the NAG/creatinine ratio and creatinine levels was observed. Preoperative split renal function of the affected kidney was less than 45% in 39% of cases, normal in 44%, and greater than 55% in 17%; in these three subgroups, no differences in renal function markers were found., Conclusions: The most sensitive parameter to detect alterations in renal function in children with UPJO is the UOsm and, therefore, the most useful in the follow-up after surgery. No correlation was found between other functional and morphological parameters obtained on renal ultrasound and renogram., Competing Interests: Conflicts of interest None., (Copyright © 2021 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.)

Background: Several recent studies reported bone mineral density (BMD) reduction in pediatric patients with idiopathic hypercalciuria (IH). This longitudinal study aimed to evaluate BMD evolution in IH patients through three bone densitometry studies conducted over 20 years on average. A second objective was to evaluate urine calcium and citrate excretion during this period., Methods: Case notes of 34 patients diagnosed with IH at age 7.9 ± 3, alongside results of two bone densitometry studies, performed at 10.5 ± 2.7 (BMD1) and 14.5 ± 2.7 (BMD2) years of age, were reviewed. Patients underwent a third densitometry study in adulthood (BMD3) aged 28.3 ± 2.9. Mean follow-up duration (time-lapse between BMD1 and BMD3) was 17.7 ± 1.4 years., Results: Statistically significant differences were found between z-BMD3 (- 0.85 ± 1.10) and z-BMD1 (- 1.47 ± 0.99) (P = 0.001) as well as between z-BMD3 and z-BMD2 (- 1.33 ± 1.20) (P = 0.016). At the end of follow-up, z-BMD3 was superior to z-BMD2 in 23 adult patients (67.6%) and lower in 11 patients (5M, 6F; 32.3%). Both men and women showed increased bone mass over time, although such increases were significant only for women. The gradual decrease observed in calcium/creatinine and citrate/creatinine ratios could be related to improvement in osteoblastic activity and especially reduction in osteoclastic activity., Conclusions: In patients with IH, BMD improves, which may be related especially to female sex, increment of body mass, and reduction in bone resorption. Upon reaching adulthood, urine calcium and citrate excretion tend to decrease so lithogenic risk still remains. The cause of the latter is unknown, although it likely relates to changes in bone activity.

Objective: Nowadays, the algorithms for the study of hydronephrosis in children include voiding cystourethrogram (VCUG) and diuretic renogram (DR) in all patients. Both are invasive, distressing, and associated with radiation risk. However, basic renal function tests (bRFTs) are not included. This study was designed to determine whether bRFTs may help avoid VCUG and/or DR in some children., Methods: Retrospective review of hydronephrosis (≥20 mm renal pelvis) patient records over one year (n = 38) (pyeloureteral stenosis (PUS) n = 12; high-grade vesicoureteral reflux (VUR) n = 8; non-obstructive hydronephrosis (NOH) n = 18. Data from the three protocolized bRFTs (maximum urine osmolality after DDAVP (UOsm), albumin/creatinine ratio (Alb/Cr), and NAG/creatinine ratio (NAG/Cr), together with VCUG and DR, were analyzed., Results: 38 hydronephrosis patients (pyeloureteral stenosis (PUS) n = 12; high grade vesicoureteral reflux (VUR) n = 8; non-obstructive hydronephrosis (NOH) n = 18. UOsm was decreased in 100% of VUR patients, 75% of PUS patients, and 16.7% of NOH patients. Alb/Cr ratio was increased in 62.5% of VUR patients, 8.3% of PUS patients, and 11.1% of NOH patients. NAG/Cr ratio was increased in 42.8% of VUR patients, 25% of PUS patients, and 6.7% of NOH patients. UOsm was decreased in most patients who required surgery (100% of VUR patients and 74% of PUS patients), but only in 11.1% of patients who did not (NOH group)., Conclusions: These results suggest that bRFTs may be useful in delaying or avoiding VCUG in some hydronephrosis cases. UOsm is the most sensitive test. No child with (high grade) VUR had a normal UOsm. VCUG could have been avoided in 43% of our patients -with a normal UOsm- without missing any high grade VUR.

Introduction: There is much debate about whether idiopathic hypercalciuria (IH) affects kidney water management. For the first time in the literature, we carried out a longitudinal study of kidney water management (KWM) in patients diagnosed with IH in childhood and followed-up until adulthood (mean follow-up 17.7±1.4 years)., Methods: Twenty-nine patients (7 M, 22 F) over the age of 24 years (mean 28.2±2.9 years, range: 24.1-35.9) who were diagnosed with IH in childhood (mean 7.6±3.2 years, range: 1-14) were included. Maximum urine osmolality (UO) and/or urine volume adjusted for 100ml of glomerular filtration rate (V/GFR) in both age groups (paediatric and adult) were determined. Moreover, whenever possible, in both age groups plasma creatinine levels, plasma sodium levels, uric acid levels, the citrate/creatinine ratio and the calcium/citrate ratio were recorded and a renal and bladder ultrasound was performed., Results: In the paediatric age group, KWM was altered in 9/29 cases (31%) (4 with reduced maximum UO and 5 with elevated V/GFR). In adulthood, KWM was found to be affected in 7/29 cases (24.1%) (6 with reduced UO and one with elevated V/GFR). Compared to the paediatric age group, adult patients had lower V/GFR, calcium/creatinine and citrate/creatinine values, as well as higher plasma creatinine, uric acid and calcium/citrate. There were no differences in the maximum UO in both age groups. However, UO in adulthood was significantly lower in subjects who had renal colic compared to those who did not (P=.04)., Conclusions: KWM was affected in approximately one third of patients with IH, which persisted 20 years after diagnosis. We think that these results may be due to adherence to the recommended protective diet and to the pharmacological treatment administered at the diagnosis of IH during childhood., (Copyright © 2019. Published by Elsevier España, S.L.U.)

Idiopathic hypercalciuria (IH) is defined as that clinical situation in which an increase in urinary calcium excretion is observed, in the absence of hypercalcemia and other known causes of hypercalciuria. In recent years, its diagnosis in pediatric age has been more frequent because it has been known that it can debut with very different symptoms, in the absence of kidney stone formation. The discovery of genetic hypercalciuric stone-forming rats has allowed us to glimpse the pathophysiological mechanism of IH since they show many data in common with humans with IH as normal levels of blood calcium, intestinal calcium hyperabsorption, increased bone resorption and a defect in the renal tubular calcium reabsorption. In 1993, it was shown that in these animals there is an increase in the number of vitamin D receptors (VDR) in the intestine, which favors an increase in the functional capacity of calcitriol-VDR complexes that explains the increase in intestinal transport of calcium. The same happens at the bone level producing a greater resorption. In our opinion, IH is a 'metabolic anomaly' or, better, an inheritable constitutive metabolic characteristic. In this sense, what patients with IH would inherit is the availability of having a greater number of VDRs in their cells than those with normal urinary calcium excretion. IH cannot be considered a sensu stricto disease, so pharmacological treatment must be individualized., (Copyright © 2019 Sociedad Española de Nefrología. Published by Elsevier España, S.L.U. All rights reserved.)

The 50th Anniversary of Anales de Pediatría is a good time for the celebration of events and tributes, and also for critical thought. Anales de Pediatría is the official publication of scientific expression of the Spanish Association of Paediatrics (AEP). It has been published continuously since October 1968. Anales has contributed so much to the narrative of the advances in Spanish paediatrics, as well as the AEP. Throughout its 50 years of history, the editorial teams of the journal have worked to streamline its management, improve the quality of the content, and to ensure its dissemination and national-international visibility. From 1968 to 1972, Anales was published as a Journal-bulletin. From 1977 until 2000, presence of original articles. Since the year 2000, continuous modernisation and recognition with international journals of prestige, indexing in SCI-JCR, impact from 2009, electronic management of manuscripts, Spanish/English from the 2014 Edition. The evolution of the journal is reviewed in this article. With this, the AEP history committee wants to collaborate in a greater understanding of the development of Spanish paediatrics, as well as to present the history of Anales to its authors and readers. The History committee proposes that a small percentage of space is destined for the humanities and to the humanisation of paediatrics. Best information will ensure the best care for children and also for paediatricians., (Copyright © 2018 Asociación Española de Pediatría. Publicado por Elsevier España, S.L.U. All rights reserved.)

Two cases of children diagnosed with renal tubular acidosis (RTA) associated with autoimmune hypothyroidism are presented. Case 1 developed an intestinal ileus at the age of five in the context of a respiratory problem. The tests performed confirmed metabolic acidosis, hyperchloraemia, hypokalaemia and nephrocalcinosis. Case 2 was diagnosed with hypothyroidism at the age of 11, and with RTA two years later. In both patients, the diagnosis of RTA was verified when decreased maximum urinary pCO 2 was found. In case 2, a proximal bicarbonate leak (type 3 RTA) was also confirmed. This was the first case to be published on the topic. The causes of RTA in patients with hypothyroidism are reviewed. The deleterious effect on the kidneys may be due to the absence of thyroid hormone and/or autoantibodies in the cases of autoimmune hypothyroidism., (Copyright © 2018 Sociedad Española de Nefrología. Published by Elsevier España, S.L.U. All rights reserved.)

Background: Various genetic and environmental factors are involved in urolithiasis. The 2 most common metabolic abnormalities are the increase in urinary calcium and low urinary citrate excretion. The ratio calculated between the concentrations of both substances is a good risk marker for the formation of calcium stones., Objectives: To determine whether the risk of urinary calcium stone formation changes throughout the day in the same patient., Methods: We studied 56 children (23V, 33M) to check if they had prelithiasis. Calcium, citrate, and creatinine concentrations were determined in two urine samples collected one before dinner and the other in the morning. It was collected if they had ultrasound stones and if there was a history of urolithiasis in first and/or second degree relatives., Results: In 25 patients (44.6%), renal ultrasound was positive for lithiasis (stones [n=9] and microlithiasis [n=16]). Forty of the 56 families (71.4%) had a history of urolithiasis. The percentage of abnormal urinary calcium (28.6%) concentrations and an abnormal calcium/citrate ratio (69.6%) was higher in the first urine of the day. The calcium/citrate ratio was the only studied parameter that was related to a family history of urolithiasis. There were no differences in urinary parameters between patients with and without ultrasound-confirmed kidney stones., Conclusions: Urinary concentrations of calcium and the calcium/citrate ratio vary throughout the day. Urine produced at night has a higher risk of urinary calcium stone formation., (Copyright © 2017 Sociedad Española de Nefrología. Published by Elsevier España, S.L.U. All rights reserved.)

Objective: The aim of this exploratory study was to analyze the urinary excretion of Clara cell protein (CC16), a new marker of proximal tubular dysfunction (PTD), in kidney transplantation (KT)., Materials and Methods: Urinary concentrations of CC16, β2-microglobulin (β2m), and N-acetyl-glucosaminidase (NAG) were measured in 50 KT patients (72% men; mean age 50.4 ± 12.4 years; diabetes in 24%; duration of KT 4.3 ± 3.1 years) and 10 healthy controls (6 men; mean age 33.6 ± 13.4 years)., Results: Urinary levels of β2m, NAG, and CC16 were significantly higher in KT patients than in controls: β2m: 0.77 (interquartile range [IQ] 0.22 to 4.62) g/g vs 0.069 (IQ 0.05 to 0.10) g/g; NAG: 3.16 (IQ 2.09 to 5.33) U/g vs 1.73 (IQ 1.25 to 2.07) U/g; CC16: 26.01 (IQ 8.62 to 123.3) g/g vs 2.51 (IQ 0.83 to 7.18) g/g (P < .001). Elevated levels of β2m, NAG, and CC16 were found in 81%, 28%, and 71% of KT patients, respectively. Urinary levels of β2m, NAG, and CC16 significantly increase as glomerular filtration rate (GFR) decreases. Interestingly, in patients with GFR >60 mL/min, we still found high levels of β2m, NAG, and CC16 in 77%, 13%, and 52%, respectively. Diabetic subjects had significant higher levels of the 3 markers compared with nondiabetic subjects, without differences in albumin excretion or GFR. CC16 showed a positive correlation with urinary albumin (r = 0.42, P < .001), NAG (r = 0.352, P < .05), and β2m (r = 0.75, P < .001)., Conclusion: PTD is highly prevalent in KT patients. This is the first study that analyzes CC16 in KT patients, showing that the urinary excretion of this protein is significantly increased in this population. Further studies are needed to examine the clinical value of CC16 in KT patients., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Basic renal function tests such as maximum urine osmolality and urinary elimination of albumin and N-acetyl-glucosaminidase often reveal abnormalities in clinical cases involving hyperpressure in the urinary tract or loss of renal parenchyma. However, in all the available algorithms dedicated to the study of children with urinary tract infection or dilation, the benefit of using these functional parameters is not mentioned. In this review, we provide information about the practical usefulness of assessing the basic renal function parameters. From these data, we propose an algorithm that combines morphological and functional parameters to make a reasoned case for voiding cystourethrography., (Copyright © 2016 Sociedad Española de Nefrología. Published by Elsevier España, S.L.U. All rights reserved.)

Unlabelled: Molecular diagnosis is a useful diagnostic tool in primary nephrogenic diabetes insipidus (NDI), an inherited disease characterized by renal inability to concentrate urine. The AVPR2 and AQP2 genes were screened for mutations in a cohort of 25 patients with clinical diagnosis of NDI. Patients presented with dehydration, polyuria-polydipsia, failure to thrive (mean ± SD; Z-height -1.9 ± 2.1 and Z-weight -2.4 ± 1.7), severe hypernatremia (mean ± SD; Na 150 ± 10 mEq/L), increased plasma osmolality (mean ± SD; 311 ± 18 mOsm/Kg), but normal glomerular filtration rate. Genetic diagnosis revealed that 24 male patients were hemizygous for 17 different putative disease-causing mutations in the AVPR2 gene (each one in a different family). Of those, nine had not been previously reported, and eight were recurrent. Moreover, we found those same AVPR2 changes in 12 relatives who were heterozygous carriers. Further, in one female patient, AVPR2 gene study turned out to be negative and she was found to be homozygous for the novel AQP2 p.Ala86Val alteration., Conclusion: Genetic analysis presumably confirmed the diagnosis of nephrogenic diabetes insipidus in every patient of the studied cohort. We emphasize that we detected a high presence (50 %) of heterozygous females with clinical NDI symptoms., What Is Known: • In most cases (90 %), inherited nephrogenic diabetes insipidus (NDI) is an X-linked disease, caused by mutations in the AVPR2 gene. • In rare occasions (10 %), it is caused by mutations in the AQP2 gene. What is new: • In this study, we report 10 novel mutations associated with NDI. • We have detected a high presence (50 %) of heterozygous carriers with clinical NDI symptoms.

Background: Primary distal renal tubular acidosis is a clinical disorder characterized by hyperchloremic metabolic acidosis, hypercalciuria, hypocitraturia, urinary acidification impairment, hypokalemia, metabolic bone disease, and nephrocalcinosis. Urinary acidification ability may be evaluated by an acidification test or maximum urinary pCO2 assessment with alkaline urine. The maximum urinary pCO2 test using acetazolamide and sodium bicarbonate is an easy test to confirm the lack of urine acidification in distal renal tubular acidosis in children., Objective: To determine the urinary acidification ability using the maximum urinary pCO2 assessment in a group of children with a distal renal tubular acidosis diagnosis., Material and Methods: Thirty children were evaluated (13 males and 17 females); 23 children had been diagnosed with distal renal tubular acidosis by other physicians and were under alkali treatment with potassium and sodium citrates (21) and bicarbonate (2), and five children were not under alkali treatment. Two children had been diagnosed with primary distal renal tubular acidosis by our medical group. The maximum urinary pCO2 was determined by the oral intake of acetazolamide and sodium bicarbonate., Results: Two cases with primary distal renal tubular acidosis were found, and they had a history of dehydration episodes during infancy and showed hyperchloremic metabolic acidosis with hypokalemia. They also exhibited urine acidification impairment with furosemide and reduced urinary pCO2 (< 60 mmHg), and the urine-blood pCO2 gradient was reduced in both cases (< 30 mmHg). One of them developed bilateral sensorineural deafness, while the other showed severe hypocitraturia. One case of proximal or type 2 renal tubular acidosis with hyperaminoaciduria was identified. Twenty-eight children displayed normal urinary acidification and did not show signs of distal renal tubular acidosis., Conclusions: The urinary acidification test with furosemide and urinary pCO2 assessment are reliable tests to identify the renal excretion of hydrogen ions (H+) and allow confirmation of the lack of urine acidification in distal renal tubular acidosis.

Background: The G1 stage of chronic kidney disease (CKD) is defined in the 2012 KDIGO Guideline as kidney damage characterized by structural or functional kidney abnormalities without deterioration of glomerular filtration rate. Albuminuria and electrolyte abnormalities due to tubular disorders are considered functional markers of kidney damage. Changes in renal water handling are not explicitly cited in these guidelines. A large sample of children with abnormal dimercaptosuccinic acid (DMSA) scan located in the G1 stage was used in this study., Methods: Ambispective, cross-sectional study to evaluate the clinical histories of 116 pediatric patients. 100 patients were included in the first group (G1 stage) and 16 patients in the G2-G5 stages according to the classification of CKD Guideline KDIGO. All the patients had a renal pathologic DMSA scan. GFR, maximum urine osmolality and albumin/creatinine and NAG/creatinine ratios were determined., Results: The patients with normal GFR, in relation to those with reduced GFR, had significantly higher values of maximum urine osmolality and significantly reduced values of urine volume and albumin/creatinine and NAG/creatinine ratios. The most frequently observed alterations in children in the KDIGO G1 stage were those involving the water renal management such as urinary concentrating ability defect (29%) and increased urinary volume (20%). The frequency of children with increased urinary elimination of albumin (12%) and NAG (3%) was more lower. All children in KDIGO G2-G5 stages had alterations in water renal management., Conclusions: The parameters related with the water renal management are affected more frequently than albumin urinary excretion in children who have loss of parenchyma and normal GFR.

Isaac Albéniz was a Spanish musician and pianist who was best known in France and England. One of his last works for piano, the suite Iberia, is well-known and identifies his country of origin. He died with terminal uraemia following longstanding chronic intestinal and kidney symptoms. Suggestions as to pathology include amyloidosis complicated by kidney stones and hypertension that sometimes manifested itself in the form of hypertensive crisis, accompanied by obesity.

Introduction: We analysed a large sample of children diagnosed with urinary tract malformations and/or infections and calculated diagnostic efficiency and quality indexes for five different functional markers, with the goal of testing which is the most sensitive for detecting a loss of renal parenchyma., Patients and Method: Ours was a cross-sectional retrospective study in which the clinical histories of 179 paediatric patients (91 male and 88 female) were evaluated. In 102 of these patients (57%), a scintigraphy revealed loss of parenchyma. The most commonly observed morphological type of damage was renal scarring. All patients had undergone at least one desmopressin urine concentration test. We also analysed albumin/creatinine and N-acetyl-glucosaminidase (NAG)/creatinine ratios, glomerular filtration rate (GFR), and urine volume., Results: By distributing patients according to normal/abnormal scintigraphy, we observed statistically significant differences between the two groups in maximum urine osmolality and GFR. Urine volume was elevated in 31.3% of cases (sensitivity: 37.9%; specificity: 81.8%) and 24% had a defect in renal concentrating ability (sensitivity: 30.4%; specificity: 84.8%). Urinary albumin excretion was high in 12.2% of patients, and 7.2% had a high NAG/creatinine ratio. GFR was low in only 5.7% of patients. These last two markers were the least sensitive but most specific for detecting a loss of renal parenchyma (100%)., Conclusions: In our study, the most sensitive functional tests for detecting the loss of renal parenchyma were the two that take into account the ability of the kidney to manage water, i.e. urine volume and maximum urine osmolality. These two tests had specificity >80%. However, the maximum specificity was obtained by the NAG/creatinine ratio and GFR, which were, conversely, the least sensitive tests. A normal GFR does not necessarily show normal renal function.

Aim: We have studied 160 children with a variety of renal diseases, 14 of them with chronic renal failure (CRF), to evaluate maximum urinary osmolality as a predictor of glomerular filtration rate (GFR) testing the hypothesis that a normal GFR is necessary to have a normal urinary concentrating capacity., Methods: All patients had a serum creatinine measured. GFR was calculated according to the Schwartz formula. All patients underwent desmopressin (DDAVP) test to evaluate renal concentrating capacity., Results: Patients with CRF were unable to concentrate the urine beyond 486 mosm/kg whereas all patients with a normal concentrating capacity (urine osmolality >835 mosm/kg) had a normal GFR. Desmopressin test sensitivity to detect CRF was 100% and specificity 70.5%. A significant negative correlation was found between urinary osmolality after DDAVP administration and serum creatinine levels and between urinary volume corrected by 100 mL of GFR (V/GFR) and urinary osmolality., Conclusion: In our series, a normal concentrating capacity was always associated with a normal GFR while all patients with decreased GFR had a concentrating capacity defect. Thus, in the evaluation of infants and children with renal disease, the finding of a normal urinary concentrating capacity will suggest and intact glomerular and tubular function.

Posterior urethral valves, unilateral vesicoureteral reflux and renal dysplasia (VURD syndrome) is an infrequent entity in childhood that has provoked multiple controversies. The shortage of studies that evaluate the long-term outcome in these children prompted up to write the present article. Three patients that met strict criteria for a diagnosis of VURD syndrome were retrospectively reviewed, with special emphasis on several indicators of renal function in these patients at diagnosis and in adulthood. The three patients currently have normal renal function, unlike a large percentage of patients diagnosed with posterior urethral valves with vesicoureteral bilateral reflux. Although the sample is small, our results support the hypothesis of good long-term renal function in affected children.

Dilation of the genitourinary tract is not always synonymous with obstruction. It is well known that malformations with apparent hydronephrosis and normal urinary flow can exist. In addition, two or more distinct malformations of the genitourinary tract can coexist in the same patient. We present a case of coexistence of a unilateral multicystic dysplastic kidney and contralateral megacalycosis associated with ipsilateral distal segmental megaureter. This association is unusual in the literature. Glomerular renal function was normal, with only a slight defect of renal concentration capacity.

We studied 34 asymptomatic children who were born with a very-low-birth-weight (VLBW) and had no perinatal history of acute renal failure nor treatment with furosemide. The study was done at preschool or school age, looking for echographic changes and renal tubular disturbances which are known to predispose to renal lithiasis. The results were compared with those of a control group of 18 children who had been born at term with a body weight >2,500 g. One or more renal tubular disturbances were found in 64.70% of the VLBW children. Most frequently found were decreased ammonium excretion in response to furosemide (38.23%), enhanced N-acetylglucosaminidase excretion (35.29%), hypercalciuria (26.47%), and hypocitraturia (23.53%). Echography revealed renal cortical hyperechogenicity (17.65%) and renal lithiasis (8.82 %) in some of the VLBW children. We found a significant positive correlation (r = 0.7) between the perinatal level of plasma phosphate and the total amount of H+ excreted in response to furosemide at preschool or school age. Because these renal tubular anomalies may be precursors of future lithiasis, and the renal function and echography tests are not invasive, we suggest that renal tubular function be measured and followed up in every VLBW child, particularly when perinatal hypophosphatemia has occurred.

We studied the urinary elimination of two indicators of renal proximal tubular function. N-Acetyl-Gluosaminidase (NAG) and beta 2 microglobulin (beta 2m) in 23 healthy and 67 diabetic children aged 2-15 years and with disease evolution times between 1 month and 12 years. In order to obviate the variations of glomerular filtration present in the diabetes, both proteins were evaluated in the form of indices of excretion (IE). It was found that the diabetic children as a whole presented higher values of NAGIE than the controls (p less than 0.001), and that this increased as the degree of metabolic control worsened, the latter being judged by either fructosamin or HbA C (r = 0.59 for both). The increase in the urinary elimination of NAG had a directly proportional relation with the evolution time of the diabetes. With respect to the beta 2mIE, no significant differences were found on dividing the children according to the degree of metabolic control, although the values did increase with longer evolution times. Thus it may be concluded that NAGIE was shown to be a more useful parameter than beta 2m for evaluating the renal proximal tubular function in infant and juvenile diabetes.