Long-term growth of children with nephrogenic diabetes insipidus.

Primary nephrogenic diabetes insipidus (NDI) is a genetic, chronic disease characterised by lack of distal renal tubule to antidiuretic hormone. The condition produces polyuria, polydipsia, and consequently, reduced caloric intake and growth failure. There is very scarce information on physical growth of affected children. The objective of the paper is to describe long-term growth of 14 patients from 11 families, studied retrospectively and followed for 3-16 years (median 11.6 years). Diagnosis was made on the basis of clinical and laboratory data and concentration test under pitressin. Patients were treated with indomethacin, thiazides, and amiloride. Weight and standing height was measured periodically at the Laboratory of Anthropometry, following standardised techniques. Information was obtained from clinical notes. The majority of children grew below the third centile of local standards, and many showed improvement of weight, height, and body mass index (BMI) over time. Mean height, weight, and BMI gain during follow-up was 1.72, 1.06, and 1.46 standard deviations (SDs), respectively. Three children who did not adhere to treatment showed growth delay. Height gain during the first 2 years of follow-up was inversely associated with height deficit at diagnosis. Further studies on growth at adolescence and in different mutations are recommended.