TY - JOUR
T1 - Incomplete Distal Renal Tubular Acidosis and Kidney Stones
AU - Fuster, Daniel G.
AU - Moe, Orson W.
N1 - Funding Information:
Disclosures: D.G.F. has served as a consultant for Otsuka Pharmaceuticals. D.G.F. has received unrestricted research funding from Novartis, AbbVie, and Otsuka Pharmaceuticals. O.W.M. served on the Advisory Boards for AbbVie, Allena, Ardelyx, Genzyme-Sanofi, and Tricida.
Funding Information:
D.G.F. was supported by the Swiss National Center of Competence in Research (NCCR) TransCure and the Swiss National Science Foundation (grants: 31003A_135503, 31003A_152829, and 33IC30_166785/1). O.W.M. was supported by the National Institutes of Health (P30 DK-079328, R01 DK081423, and T32DK007257), the American Heart Foundation, and the Charles Pak Foundation.
Publisher Copyright:
© 2018 National Kidney Foundation, Inc.
PY - 2018/7
Y1 - 2018/7
N2 - Renal tubular acidosis (RTA) is comprised of a diverse group of congenital or acquired diseases with the common denominator of defective renal acid excretion with protean manifestation, but in adults, recurrent kidney stones and nephrocalcinosis are mainly found in presentation. Calcium phosphate (CaP) stones and nephrocalcinosis are frequently encountered in distal hypokalemic RTA type I. Alkaline urinary pH, hypocitraturia, and, less frequently, hypercalciuria are the tripartite lithogenic factors in distal RTA (dRTA) predisposing to CaP stone formation; the latter 2 are also commonly encountered in other causes of urolithiasis. Although the full blown syndrome is easily diagnosed by conventional clinical criteria, an attenuated forme fruste called incomplete dRTA typically evades clinical testing and is only uncovered by provocative acid-loading challenges. Stone formers (SFs) that cannot acidify urine of pH < 5.3 during acid loading are considered to have incomplete dRTA. However, urinary acidification capacity is not a dichotomous but rather a continuous trait, so incomplete dRTA is not a distinct entity but may be one end of a spectrum. Recent findings suggest that incomplete dRTA can be attributed to heterozygous carriers of hypofunctional V-ATPase. The value of incomplete dRTA diagnosis by provocative testing and genotyping candidate genes is a valuable research tool, but it remains unclear at the moment whether they alter clinical practice and needs further clarification. No randomized controlled trials have been performed in SFs with dRTA or CaP stones, and until such data are available, treatment of CaP stones are centered on reversing the biochemical abnormalities encountered in the metabolic workup. SFs with type I dRTA should receive alkali therapy, preferentially in the form of K-citrate delivered judiciously to treat the chronic acid retention that drives both stone formation and bone disease.
AB - Renal tubular acidosis (RTA) is comprised of a diverse group of congenital or acquired diseases with the common denominator of defective renal acid excretion with protean manifestation, but in adults, recurrent kidney stones and nephrocalcinosis are mainly found in presentation. Calcium phosphate (CaP) stones and nephrocalcinosis are frequently encountered in distal hypokalemic RTA type I. Alkaline urinary pH, hypocitraturia, and, less frequently, hypercalciuria are the tripartite lithogenic factors in distal RTA (dRTA) predisposing to CaP stone formation; the latter 2 are also commonly encountered in other causes of urolithiasis. Although the full blown syndrome is easily diagnosed by conventional clinical criteria, an attenuated forme fruste called incomplete dRTA typically evades clinical testing and is only uncovered by provocative acid-loading challenges. Stone formers (SFs) that cannot acidify urine of pH < 5.3 during acid loading are considered to have incomplete dRTA. However, urinary acidification capacity is not a dichotomous but rather a continuous trait, so incomplete dRTA is not a distinct entity but may be one end of a spectrum. Recent findings suggest that incomplete dRTA can be attributed to heterozygous carriers of hypofunctional V-ATPase. The value of incomplete dRTA diagnosis by provocative testing and genotyping candidate genes is a valuable research tool, but it remains unclear at the moment whether they alter clinical practice and needs further clarification. No randomized controlled trials have been performed in SFs with dRTA or CaP stones, and until such data are available, treatment of CaP stones are centered on reversing the biochemical abnormalities encountered in the metabolic workup. SFs with type I dRTA should receive alkali therapy, preferentially in the form of K-citrate delivered judiciously to treat the chronic acid retention that drives both stone formation and bone disease.
KW - Acidification test
KW - Alkali therapy
KW - Kidney stones
KW - Renal tubular acidosis
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U2 - 10.1053/j.ackd.2018.05.007
DO - 10.1053/j.ackd.2018.05.007
M3 - Review article
C2 - 30139463
AN - SCOPUS:85051681172
SN - 1548-5595
VL - 25
SP - 366
EP - 374
JO - Advances in Chronic Kidney Disease
JF - Advances in Chronic Kidney Disease
IS - 4
ER -