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Background: Vitamin D supplements are readily available as over-the-counter preparations. However, although rare, cases of vitamin D overdose still occur and are associated with nephrocalcinosis and life-threatening hypercalcemia. Errors in manufacturing of nutritional supplements may be a cause of vitamin D intoxication in children. This study aimed to identify factors associated with vitamin D overdose-related nephrocalcinosis in children due to manufacturing errors in supplements., Methods: This retrospective study reviewed medical charts of pediatric patients with non-registered supplement-related vitamin D overdose at a tertiary referral hospital between 2006 and 2011. Clinical and laboratory characteristics of patients with or without nephrocalcinosis were evaluated. Receiver operating characteristics curve and area under the receiver operating characteristics curve were used to determine the most predictive value of each characteristic., Results: A total of 44 patients (males: 29; age: 7-62 months) were included. Age ≤ 16.5 months, body weight ≤ 10.25 kg, body height ≤ 78.5 cm, body surface area (BSA) ≤ 0.475 m 2 , 25-hydroxyvitamin D 3  ≥ 143 ng/mL, and calcium ≥ 10.65 mg/dL were predictive of developing nephrocalcinosis with a sensitivity and specificity of > 60%. Univariant analysis revealed that BSA was the most significant anthropometric prognostic factor (odds ratio: 12.09; 95% confidence interval: 2.61-55.72; P = 0.001)., Conclusions: Children with smaller BSAs were more vulnerable to high-dose vitamin D 3 -related nephrocalcinosis. Physicians and parents should be aware of the potential adverse effects of vitamin D overdose in children. A higher resolution version of the Graphical abstract is available as Supplementary information., (© 2022. The Author(s), under exclusive licence to International Pediatric Nephrology Association.)

Context: Options for chronic treatment of hypoparathyroidism include calcitriol, recombinant human parathyroid hormone, and high-dose vitamin D (D2). D2 is used in a minority of patients because of fear of prolonged hypercalcemia and renal toxicity. There is a paucity of recent data about D2 use in hypoparathyroidism., Objective: Compare renal function, hypercalcemia, and hypocalcemia in patients with hypoparathyroidism treated chronically with either D2 (D2 group) or calcitriol., Design, Setting, and Patients: A retrospective study of patients with hypoparathyroidism treated at the University of Maryland Hospital. Participants were identified by a billing record search with diagnosis confirmed by chart review. Thirty patients were identified; 16 were treated chronically with D2, 14 with calcitriol. Data were extracted from medical records., Main Outcome Measures: Serum creatinine and calcium, hospitalizations, and emergency department (ED) visits for hypercalcemia and hypocalcemia., Results: D2 and calcitriol groups were similar in age (58.9 ± 16.7 vs 50.9 ± 22.6 years, P = 0.28), sex, and treatment duration (17.8 ± 14.2 vs 8.5 ± 4.4 years, P = 0.076). Hospitalization or ED visits for hypocalcemia occurred in none of the D2 group vs four of 14 in the calcitriol group (P = 0.03); three in the calcitriol group had multiple ED visits. There were no differences between D2 and calcitriol groups in hospitalizations or ED visits for hypercalcemia, serum creatinine or calcium, or kidney stones., Conclusion: We found less morbidity from hypocalcemia in hypoparathyroid patients treated chronically with D2 compared with calcitriol and found no difference in renal function or morbidity from hypercalcemia. Treatment with D2 should be considered in patients with hypoparathyroidism, particularly in those who experience recurrent hypocalcemia., (Copyright © 2017 by the Endocrine Society)

Public concern over vitamin D deficiency has led to widespread use of over the counter (OTC) vitamin D (-D3 or -D2) supplements, containing up to 10,000 IU/unit dose (400 IU=10μg). Overzealous use of such supplements can cause hypercalcemia due to vitamin D toxicity. Infants are particularly vulnerable to toxicity associated with vitamin D overdose. OTC supplements are not subject to stringent quality control regulations from FDA and high degree of variability in vitamin D content in OTC pills has been demonstrated. Other etiologies of vitamin D induced hypercalcemia include hyperparathyroidism, granulomatous malignancies like sarcoidosis and mutations in the CYP24A1 gene. The differential diagnosis of hypercalcemia should include iatrogenic and genetic etiologies. C24-hydroxylation and C3-epimerization are two important biochemical pathways via which 25-hydroxyvitamin D3 (25(OH)D3) is converted to its metabolites, 24,25-dihydroxyvitamin D3 (24,25(OH)2D3) or its C3 epimer, 3-epi-25-OH-D3 respectively. Mutations in the CYP24A1 gene cause reduced serum 24,25(OH)2D3 to 25(OH)D3 ratio (<0.02), elevated serum 1,25-dihydroxyvitamin D (1,25(OH)2D3), hypercalcemia, hypercalciuria and nephrolithiasis. Studies in infants have shown that 3-epi-25(OH)D3 can contribute 9-61.1% of the total 25(OH)D3. Therefore, measurements of parathyroid hormone (PTH) and vitamin D metabolites 25(OH)D3, 1,25(OH)2D3, 3-epi-25(OH)D3 and 24,25(OH)2D3 are useful to investigate whether the underlying cause of vitamin D toxicity is iatrogenic versus genetic. Here we report a case of vitamin D3 associated toxicity in a 4-month-old female who was exclusively breast-fed and received an oral liquid vitamin D3 supplement at a dose significantly higher than recommended on the label. The vitamin D3 content of the supplement was threefold higher (6000 IU of D/drop) than listed on the label (2000 IU). Due to overdosing and higher vitamin D3 content, the infant received ∼50,000 IU/day for two months resulting in severe hypercalcemia, hypercalciuria and nephrocalcinosis. We also review the relevant literature on vitamin D3 toxicity in this report., (Copyright © 2015. Published by Elsevier Ltd.)

In hypophosphatemic rickets, there are both inherited and acquired forms, where X-linked dominant hypophosphatemic rickets (XLH) is the most prevalent genetic form and caused by mutations in the phosphate-regulating endopeptidase (PHEX) gene. XLH is associated with growth retardation and bone deformities. The renal tubular cells have an important role in calcium and phosphate metabolism, where the 1alpha-hydroxylase enzyme metabolizes the conversion of 25 (OH)-vitamin D to potent 1,25 (OH)2-vitamin D, whereas the sodium-phosphate transporter controls tubular phosphate reabsorption. The pathophysiological defect in XLH is speculated to cause an increase in a circulating phosphate regulating hormone termed phosphatonin (fibroblast growth factor 23 is the primary phosphatonin candidate), which leads to inhibition of 1alpha-hydroxylase, and simultaneously to inhibition of the sodium-phosphate transporter domain NPT2c leading to parathyroid hormone-independent phosphaturia. Hence, current treatment of XLH is 1,25 (OH)2-vitamin D or the vitamin D analog alfacalcidol and elementary phosphorus. Unfortunately, patients with XLH may develop nephrocalcinosis, secondary or tertiary hyperparathyroidism, and in some situations also hypertension and cardiovascular abnormalities. We describe a patient with XLH caused by a novel missense mutation in the PHEX gene, who on treatment with alfacalcidol and oral phosphate had normal growth and minimal bone deformities, but who subsequently developed moderate nephrocalcinosis, significant hyperparathyroidism, hypercalcemia, renal failure, and hypertension. We also report the use of the calcimimetic drug cinacalcet in the successful treatment of hypercalcemia and hyperparathyroidism.

In recent years, alendronate, an oral biphosphonate, has been added to therapy of hypercalcemia secondary to vitamin D intoxication in children. Alendronate may cause mucosal ulcerations in the mouth and esophagus. We report our experience in two infants with vitamin D intoxication to whom alendronate therapy was administered through nasogastric tube, an alternate route for alendronate administration.

Vitamin D intoxication is a well-known cause of hypercalcemia in children. We report here the use of oral alendronate for the treatment of hypercalcemia due to vitamin D intoxication in a 7 month-old infant with nephrocalcinosis. The serum calcium levels were normalized without complications. Oral alendronate therapy may be safely used in hypercalcemia due to vitamin. D intoxication in pediatric patients with nephrocalcinosis resistant to hydration, diuretics or corticosteroids.

Background: Cardiovascular diseases are very common in patients with end-stage renal disease and are the underlying cause of approximately half the deaths in dialysis patients. In those patients vascular calcifications are typically seen in the tunica media and therefore represent histopathological changes different to those in atherosclerosis. For the evaluation of cardiovascular risk in chronic dialysis patients, a method is needed to reliably identify patients who have to undergo invasive diagnostics. Coronary artery calcium assessed by electron beam computed tomography (EBT) has been suggested to measure the extent of coronary atherosclerosis in patients with normal renal function. It might also be of value in the stratification of cardiovascular risk in patients with renal failure., Case Report: We report the case of a 21-year-old female with end-stage renal disease as a result of idiopathic infantile hypercalcemia with nephrocalcinosis and extensive vascular calcification. Due to a total atrioventricular block, a 2-chamber pacemaker had been implanted in 1998. Because of a very high calcium score in EBT, depressed left ventricular function in echocardiography, and limited physical strength she was sent to coronary angiography. Severe 2-vessel coronary artery disease was found and successfully treated by balloon angioplasty. She was then listed for renal transplantation. Angiographic 6-month follow-up showed an excellent long-term result., Conclusion: This case demonstrates that coronary artery disease can also be present in young dialysis patients. Discrimination of atherosclerotic vascular calcification and tunica media sclerosis typical in dialysis patients without hemodynamic effects is difficult. EBT allows for the direct detection of coronary calcium. Its extent correlates with coronary atherosclerosis and the probability of acute coronary syndromes in patients with normal renal function. This evidence has not been proved for dialysis patients, yet. However, EBT may be of value in the stratification of cardiovascular risk for patients awaiting renal transplantation.

Vitamin D is required for the normal development of teeth and bones. When there is excess vitamin D, systemic and dental changes may occur. This is a case report of a girl who experienced hypercalcemia secondary to excess vitamin D derived from the consumption of milk that was incorrectly fortified. The changes in the permanent dentition to date are enamel hypoplasia and focal pulp calcification. These changes correspond to the timing of the toxemia caused by hypervitaminosis D.

Fifteen cases of hypervitaminosis D in childhood are reviewed. In all of them, vitamin D was given following medical prescription. In four occasions, excessive dosage of vitamine D impaired the evolution of a previous nephropathy. The clinical, analytical, radiological and histological findings as well as the therapeutical aspects are commented. Hypercalcemia, hypercalciuria, polyuria with hypostenuria, renal failure, bone lesions and nephrocalcinosis are the most prominent features of the picture. Occasionally, arterial hypertension and glycosuria were found. Prednisone, thyrocalcitonine and phosphates were used as therapeutical means. In spite of nephrocalcinosis and renal failure generally present at diagnosis, the clinical course was rather good.

Peptides containing residues 1-34 of the human parathyroid hormone (PTH)-like hypercalcemic factor (hHCF), termed hHCF-(1-34)-NH2, produce effects similar to those of PTH in several biological systems in vitro and in vivo. However, there is conflicting evidence regarding the potency of hHCF on bone and, by implication, its role in calcium mobilization and the skeletal contribution to tumor-associated hypercalcemia. To resolve this conflict, the effects of infusing either hHCF-(1-34)-NH2 or a peptide containing residues 1-34 of bovine PTH [bPTH-(1-34)] into unrestrained thyroparathyroidectomized rats on a low calcium diet were compared. Direct effects on bone histology and serum calcium levels, which are totally dependent on calcium mobilization from bone in these animals, were examined. bPTH-(1-34) and hHCF-(1-34)-NH2 were equipotent in producing dose-dependent calcium mobilization from bone. At an infusion rate of 0.1 nmol/hr, both peptides produced hypercalcemia and extensive nephrocalcinosis. Histomorphometric analysis of tibiae from these animals after 48 hr of peptide infusion showed a dose-related increase in osteoclast number from 3-5 cells per mm2 at 0.01 nmol/hr to approximately equal to 32 cells per mm2 at 0.1 nmol/hr of hHCF or bovine PTH. These findings indicate that hHCF has a direct PTH-like effect on bone and, in this model system, the hHCF-(1-34)-NH2 is equipotent to bPTH-(1-34).