Parathyroid hormone and phosphate homeostasis in patients with Bartter and Gitelman syndrome: an international cross-sectional study.

BACKGROUND: Small cohort studies have reported high parathyroid hormone (PTH) levels in patients with Bartter syndrome and lower serum phosphate levels have anecdotally been reported in patients with Gitelman syndrome. In this cross-sectional study, we assessed PTH and phosphate homeostasis in a large cohort of patients with salt-losing tubulopathies. METHODS: Clinical and laboratory data of 589 patients with Bartter and Gitelman syndrome were provided by members of the European Rare Kidney Diseases Reference Network (ERKNet) and the European Society for Paediatric Nephrology (ESPN). RESULTS: A total of 285 patients with Bartter syndrome and 304 patients with Gitelman syndrome were included for analysis. Patients with Bartter syndrome type I and II had the highest median PTH level (7.5 pmol/L) and 56% had hyperparathyroidism (PTH >7.0 pmol/L). Serum calcium was slightly lower in Bartter syndrome type I and II patients with hyperparathyroidism (2.42 versus 2.49 mmol/L; P = .038) compared to those with normal PTH levels and correlated inversely with PTH (rs -0.253; P = .009). Serum phosphate and urinary phosphate excretion did not correlate with PTH. Overall, 22% of patients had low serum phosphate levels (phosphate-standard deviation score < -2), with the highest prevalence in patients with Bartter syndrome type III (32%). Serum phosphate correlated with tubular maximum reabsorption of phosphate/glomerular filtration rate (TmP/GFR) (rs 0.699; P < .001), suggesting renal phosphate wasting. CONCLUSIONS: Hyperparathyroidism is frequent in patients with Bartter syndrome type I and II. Low serum phosphate is observed in a significant number of patients with Bartter and Gitelman syndrome and appears associated with renal phosphate wasting.

Congenital toxoplasmosis presenting as central diabetes insipidus in an infant: a case report.

BACKGROUND: Congenital toxoplasmosis has a wide range of presentation at birth varying from severe neurological features such as hydrocephalus and chorioretinitis to a well appearing baby, who may develop complications late in infancy. While neuroendocrine abnormalities associated with congenital toxoplasmosis are uncommon, isolated central diabetes insipidus is extremely rare. CASE PRESENTATION: Here, we report on a female infant who presented with fever, convulsions, and polyuria. Examination revealed weight and length below the 3rd centile along with signs of severe dehydration. Fundal examination showed bilateral chorioretinitis. This infant developed hypernatremia together with increased serum osmolality and decreased both urine osmolality and specific gravity consistent with central diabetes insipidus. Serology for toxoplasma specific immunoglobulin M was high for both the mother and the baby and polymerase chain reaction for toxoplasma deoxyribonucleic acid was positive in the infant confirming congenital toxoplasmosis. Brain computerized tomography scans demonstrated ventriculomegaly associated with cerebral and cortical calcifications. Fluid and electrolyte abnormalities responded to nasal vasopressin therapy. CONCLUSION: This report highlights central diabetes inspidus as a rare presentation of congenital toxoplasmosis.