title: Abnormal function of renal tubules in patients with simple renal cysts.
abstract: The present study aimed to assess the function of proximal and distal tubules in patients with simple renal cysts. Thirty-one patients with simple renal cysts and 10 healthy subjects were examined. Based on the cyst fluid/plasma sodium ratio, 25 cysts were found to be of proximal origin and 6 of undetermined origin. In all patients cyst fluid and plasma concentrations of beta-2-microglobulin (beta-2-MG), sodium, potassium, calcium, phosphorus and total protein were assessed. Urinary excretions of sodium, potassium, calcium, phosphorus, beta-2-MG and Tamm-Horsfall protein (THP) were also estimated. Fractional excretion of beta-2-MG was calculated. The concentrations of beta-2-MG in fluid obtained from cysts of proximal origin were significantly higher than in fluid from cysts of undetermined origin (2.26 +/- 0 36 vs. 0.65 +/- 0.13 mg/l, p = 0.0004). Concentrations of THP (6.85 +/- 1.21 vs. 3.14 +/- 1.06 micrograms/ml, p < 0.05), and potassium (4.39 +/- 0.07 vs. 3.13 +/- 0.44 mmol/l, p < 0.05) were also higher in fluid from proximal cysts than in fluid from cysts of undetermined origin. Plasma beta-2-MG concentration was significantly higher in patients with proximal and undetermined cysts than in the control group (4.35 +/- 0.34 and 4.11 +/- 0.74 vs. 1.89 +/- 0.1 mg/l, p < 0.001). Urinary beta-2-MG excretion was also significantly higher in both groups of patients than in healthy subjects (474.8 +/- 165.9 and 346 +/- 94 vs. 100.2 +/- 19.6 micrograms/24 h, p < 0.05). Urinary THP excretion was significantly higher in patients with proximal cysts than in healthy subjects (31.0 +/- 5.1 vs. 16.3 +/- 2.5 mg/24 h, p < 0.05). From the results obtained in this study it seems that patients with simple renal cysts of proximal origin are characterized by abnormal tubular handling of beta-2-MG, and calcium and THP excretion. Thus, in patients with proximal cysts presence of a latent renal tubulopathy seems to be likely.
authors.affiliation: Department of Nephrology, Silesian University of Medicine, Katowice, Poland.
authors.forename: E
authors.initials: E
authors.lastname: Franek
authors.forename: A
authors.initials: A
authors.lastname: Bar
authors.forename: F
authors.initials: F
authors.lastname: Kokot
authors.forename: J
authors.initials: J
authors.lastname: Duława
authors.forename: A
authors.initials: A
authors.lastname: Wiecek
authors.forename: A
authors.initials: A
authors.lastname: Kochańska-Dziurowicz
authors.forename: K
authors.initials: K
authors.lastname: Bar
authors.forename: A
authors.initials: A
authors.lastname: Szkodny
authors.forename: W
authors.initials: W
authors.lastname: Pawłowski
authors.forename: J
authors.initials: J
authors.lastname: Myrta
mesh_terms: D000328:Adult; D002118:Calcium / Q000378:metabolism; D005260:Female; D006801:Humans; D007671:Kidney Concentrating Ability / Q000502:physiology; D052177:Kidney Diseases, Cystic / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology*; D007677:Kidney Function Tests; D007687:Kidney Tubules, Proximal / Q000378:metabolism / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009088:Mucoproteins / Q000378:metabolism; D012016:Reference Values; D012964:Sodium / Q000378:metabolism; D058949:Uromodulin; D001613:beta 2-Microglobulin / Q000378:metabolism
chemical_list: D009088:Mucoproteins; C548612:UMOD protein, human; D058949:Uromodulin; D001613:beta 2-Microglobulin; D012964:Sodium; D002118:Calcium