Abstract
The present study aimed to asses 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 β-2-microglobulin (β-2-MG), sodium, potassium, calcium, phosphorus and total protein were assessed. Urinary excretions of sodium, potassium, calcium, phosphorus, β-2-MG and Tamm-Horsfall protein (THP) were also estimated. Fractional excretion of β-2-MG was calculated.
The concentrations of β-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 μg/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 β-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 β-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 μg/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 β-2-MG, and calcium and THP excretion. Thus, in patients with proximal cysts presence of a latent renal tubulopathy seems to be likely.
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Franek, E., Bar, A., Kokot, F. et al. Abnormal function of renal tubules in patients with simple renal cysts. International Urology and Nephrology 27, 679–685 (1995). https://doi.org/10.1007/BF02552131
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DOI: https://doi.org/10.1007/BF02552131