Incomplete distal renal tubular acidosis affects growth in children.

BACKGROUND Incomplete distal renal tubular acidosis (idRTA) is recognized as an underlying aetiology in recurrent nephrolithiasis. Until the recently reported high prevalence of idRTA in adults with osteoporosis, the effect of idRTA on skeletal parameters was not known. We hypothesize that idRTA has a potential to affect height in the paediatric population. METHODS In a cross-sectional study, the children with posterior urethral valves (PUV), with normal estimated glomerular filtration rates, were evaluated for idRTA and complete dRTA. The idRTA evaluation was done by short ammonium chloride acidification test. The height standard deviation scores (SDS) in the idRTA group were compared with PUV children without dRTA, with complete dRTA, and to age and gender matched controls with no renal issue (n = 50). RESULTS The idRTA group (n = 17) manifested a significantly lower mean height SDS (-1.94 +/- 0.41 vs -0.46 +/- 0.28; P < 0.001) and a higher short stature prevalence (height SDS below 2) (18% vs 0; P = 0.06) as compared with those without dRTA (n = 23). The matched controls showed a significantly higher height SDS as compared with the idRTA group (-0.39 +/- 0.25 vs -1.94 +/- 0.41; P < 0.001). As compared with the complete dRTA group (n = 9), the children with idRTA did have significantly higher height SDS (-1.94 +/- 0.41 vs -5.31 +/- 1.95; P = 0.002), and a lower short stature prevalence (18% vs 78%; P = 0.001). On multivariate analysis, dRTA was significantly associated with the height SDS (= -0.88; P < 0.001). CONCLUSIONS Incomplete dRTA affects height in children. This observation needs validation in longitudinal studies.