ERYTHROPOIETIN CONCENTRATION IN CYST FLUID IN PATIENTS WITH SIMPLE RENAL CYSTS

High erythropoietin (EPO) levels in cyst fluid and blood plasma in pat ients with autosomal dominant polycystic kidney disease (ADPKD) have b een reported. In the present study we assessed EPO levels and the bioc hemical composition of cyst fluid obtained from 50 simple renal cysts. Basing on cyst fluid/plasma sodium ratio 38 cysts were classified as cysts of proximal origin, and 12 as cysts of undetermined origin. EPO concentrations in cyst fluid obtained from proximal cysts were signifi cantly higher than in fluid from cysts of undetermined origin (472.9+/ -116.2 vs. 122.1+/-33.3 mU/ml, p < 0.05). Patients with proximal cysts had significantly higher plasma EPO levels (31.8+/-3.5 mU/ml) than he althy subjects (17.3+/-1.96 mU/ml, p < 0.005). We conclude that: (1) s imple renal cysts of distal origin seem to be rare; (2) the presence o f high EPO level in cyst fluid suggests its proximal origin; (3) estim ation of cyst fluid EPO levels seems to be of similar pathogenetic val ue as the assessment of the cyst fluid/plasma sodium ratio.