Etiological Profile of Nephrocalcinosis in Children from Southern India.

OBJECTIVE

To study the etiological profile and patterns of clinical presentation of nephrocalcinosis.

METHODS

In this observational study, patients 18 years or younger, referred to the pediatric nephrology clinic with nephrocalcinosis were evaluated for etiology. Symptoms/signs at presentation, estimated glomerular filtration rate (eGFR) at presentation and follow-up, and growth parameters were recorded.

RESULTS

The etiology of nephrocalcinosis (n=54) included distal renal tubular acidosis (n=18; 33.3%), primary hyperoxaluria (n=9; 16.7%), Bartter syndrome (n=7; 13%), Dent disease (n=4; 7.4%), cystinosis, familial hypomagnesemia with hypercalciuria and idiopathic hypercalcemia of infancy (2 each). Idiopathic nephrocalcinosis was seen in 5 (9.3%) children. Clinical features included failure to thrive (53.7%), polyuria (44.4%), bony deformities (31.5%) and hypokalemic paralysis (11.1%). At a median (IQR) follow-up of 24 (8, 56) months, the mean (SD) eGFR had improved from 59 (25.5) to 77 (31.48) mL/min/1.73m2 (P<0.01). Consanguinity was present in 50% (27/54). Genetic analysis in 5 primary hyperoxaluria cases confirmed AGXT mutations in 4; and GRHPR mutation in 1 child.

CONCLUSIONS

Distal RTA, primary hyperoxaluria and Bartter syndrome were the common etiologies of nephrocalcinosis in our patient population.