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Background: Treatment for hyperphosphatemia in chronic kidney disease (CKD) involves dietary control of phosphorus intake, dialysis, and treatment with oral phosphate binders, none of which were approved by the Federal Food and Drug Administration in pediatric patients at the time of this study. Methods: This was a phase 2, multicenter study (NCT01574326) with a 2-week, randomized, placebo-controlled, fixed-dose period (FDP) followed by a 6-month, single-arm, open-label, dose-titration period (DTP), with the aim to evaluate the safety and efficacy of sevelamer carbonate (SC) in hyperphosphatemic pediatric patients with CKD. Following a 2-4 week screening phase, pediatric patients with a serum phosphorus level higher than age-appropriate levels were randomized to receive either SC or placebo as powder/tablets in 0.4-1.6 g doses, based on body surface area. The primary efficacy outcome was the change in serum phosphorus from baseline to end of the FDP in the SC versus placebo arms (analysis of covariance). The secondary outcome was mean change in serum phosphorus from baseline to end of DTP by treatment group and overall. Treatment-emergent/serious adverse events (AEs) were recorded. Results: Of 101 enrolled patients (29 centers), 66 completed the study. The majority of patients were adolescents (74%; mean age 14.1 years) and on dialysis (77%). Renal transplant was the main reason for discontinuation. SC significantly reduced serum phosphorus from baseline levels (7.16 mg/dL) during the FDP compared to placebo (least square mean difference − 0.90 mg/dL, p = 0.001) and during the DTP (− 1.18 mg/dL, p < 0.0001). The safety and tolerability of SC and placebo were similar during the FDP, with patients in both groups reporting mild/moderate gastrointestinal AEs during the DTP. Conclusions: Sevelamer carbonate significantly lowered serum phosphorus levels in hyperphosphatemic children with CKD, with no serious safety concerns identified. [ABSTRACT FROM AUTHOR]

The article presents a case study of a patient with hypomagnesemia with secondary hypocalcemia due to a missense mutation of TRPM6 gene. It notes diagnoses of hypocalcemia (HSH) after seven months of first episode; and mentions need for taking life-long magnesium supplementation due to delay of the diagnosis and noncompliance with treatment.

Following an uneventful full-term pregnancy, a 3-day-old girl presented with a focal seizure. Serological evaluation revealed hypomagnesemia and hypocalcemia. Renal ultrasonography performed because of hematuria showed bilateral nephrolithiasis. Renal wasting of calcium and magnesium was detected and urine citrate excretion was low. The hypocalcemia was refractory to calcium therapy, but responded briskly to magnesium supplementation. After 8 weeks of treatment with magnesium and calcium supplementation plus potassium citrate, the hypomagnesemia and hypocalcemia normalized spontaneously, as did the urinary calcium, magnesium, and citrate excretion. We speculate that our patient had a transient tubular defect in the thick ascending loop of Henle. [ABSTRACT FROM AUTHOR]

Hypomagnesemia with secondary hypocalcemia is a rare autosomal recessive disorder which manifests in early infancy with generalized seizures, other symptoms of neuromuscular irritability, and growth disturbances. Homozygous mutations in the magnesium transporter gene, transient receptor potential melastatin 6 (TRPM6), cause the disease. Here, we present an 8-month-old Turkish boy with a novel mutation of TRPM6. The patient, son of first-degree cousins, was hospitalized because of recurrent seizures and mild hypotonia. He had seizures since the newborn period and he had been treated with phenobarbital but there was no favorable response to therapy. His past history also revealed hypocalcemia detected on the newborn period but serum magnesium levels were not studied at that time. During hospitalization, we detected hypocalcemia, hypomagnesemia, and normal parathormone levels. Abdominal ultrasound was normal. Magnesium excretion was slightly increased. Considering the consanguinity of the parents and clinical features of the patients, genetic testing of the TRPM6 gene was performed and a novel homozygous mutation was detected as c.3178A>T. He was started on magnesium and calcium supplementation and he is symptom-free for 1 year. We would like to call attention to the measurement of serum magnesium levels in children with hypocalcemic convulsions. Early and appropriate treatment with magnesium supplementation is crucial. [ABSTRACT FROM AUTHOR]