P0234LOW URINARY CITRATE LEVELS ARE NOT SPECIFIC OF AUTOSOMAL POLYCYSTIC KIDNEY DISEASE (ADPKD) AND ARE PRESENT WHEN RENAL FUNCTION IS IMPAIRED IN ALL NEPHROPATIES

Abstract Background and Aims In polycystic kidney disease (PKD) it is frequently found a reduction in urinary citrate that is related with degree of renal impairment but it is unknown if this alteration is specific or if it is also present in other nephropathies. Recently it has been suggested that urinary citrate could be a marker of covert metabolic acidosis and reflects acid retention in chronic kidney disease (CKD). Our aim was to compare urinary citrate in PKD with other renal diseases and to show its relation with serum bicarbonate and excretion of uric acid and calcium. Method We determined citrate, calcium and uric acid in 24-hour urine in patients with PKD and with other nephropathies with varied degree of renal impairment followed in a outpatient clinic of nephrology. Results We included 291 patients, 119 with glomerular diseases, 116 with PKD, 21 with other nephropathies, and 35 patients with normal renal function. Urinary citrate was higher in women (Females 309±251 mg/gCr vs. males 181±145 mg/gCr, p<0.001) and in patients with normal renal function (normal 380±210 mg/gCr; PKD 203±166 mg/gCr; glomerular 279±282 mg/gCr; p<0,001). PKD patients showed similar values of urinary citrate to patients with glomerular diseases and with other nephropathies. We observed a progressive reduction in urinary citrate parallel to degree of renal impairment, in a comparable way among patients with PKD and glomerular diseases. We did not observe a relationship between urinary citrate and serum bicarbonate levels. Calcium and uric acid elimination in ADPKD patients was similar to other nephropathies and lower to patients with normal renal function. However, serum uric acid was significantly higher in glomerular patients than other nephropathies after adjust with glomerular filtration rate and sex. Conclusion Hypocitraturia is not specific of PKD but it is also present in all nephropathies. Urinary citrate are related to degree of renal impairment and it is not related with serum bicarbonate. We think that it could be interesting to study urinary citrate as a marker of renal function and its role as prognostic factor of renal deterioration.