Long-term treatment with potassium citrate and renal stones in medullary sponge kidney.
OBJECTIVE
Medullary sponge kidney (MSK) is a renal malformation typically associated with nephrocalcinosis and recurrent calcium stones. Incomplete distal renal tubular acidosis, hypocitraturia, and hypercalciuria are common. For stone prevention, patients with MSK generally receive the standard "stone clinic" recommendations and often receive potassium citrate (KC). However, the effect on stone recurrence of citrate treatment in these patients has never been studied.


METHODS
The issue was retrospectively analyzed on an outpatient basis in 97 patients with a radiologic diagnosis of MSK: 65 had at least one stone risk factor (SRF; hypercalciuria, hypocitraturia, hyperuricosuria, hyperoxaluria) and received KC [29 +/- 8 (SD) mEq/d]; 10 patients with SRF and 22 without received only general stone clinic suggestions. Follow-up was 78 +/- 13, 72 +/- 15, and 83 +/- 14 months, respectively. The 24-hour urinary excretion of calcium, oxalate, uric acid, citrate, and morning urine pH were investigated at baseline and at the end of follow-up.


RESULTS
Parallel to a significant rise in urinary citrate and decreased urinary calcium (all P < 0.001), KC led to a dramatic reduction in the stone event rate (from 0.58 to 0.10 stones/yr per patient). The existence of a group of patients with MSK, those without SRF, with a very low stone rate and no SRF was recognized.


CONCLUSIONS
Treatment with KC is effective in preventing renal stones in the typical patient with MSK. It seems that two clinical phenotypes among patients showing typical MSK features during radiologic study exist.
Fabris
Antonia
A
Division of Nephrology, Department of Biomedical and Surgical Sciences, University Hospital of Verona, Verona, Italy.
Lupo
Antonio
A
Bernich
Patrizia
P
Abaterusso
Cataldo
C
Marchionna
Nicola
N
Nouvenne
Antonio
A
Gambaro
Giovanni
G
D000293:Adolescent; D000328:Adult; D015415:Biomarkers / Q000652:urine; D016009:Chi-Square Distribution; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007558:Italy; D007669:Kidney Calculi / Q000209:etiology / Q000517:prevention & control* / Q000652:urine; D008297:Male; D007691:Medullary Sponge Kidney / Q000150:complications / Q000000981:diagnostic imaging / Q000188:drug therapy* / Q000652:urine; D019357:Potassium Citrate / Q000008:administration & dosage*; D011859:Radiography; D012008:Recurrence; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome; D055815:Young Adult
D015415:Biomarkers; D019357:Potassium Citrate