Plasma levels of 7B2 (a novel pituitary polypeptide) and its molecular forms in plasma and urine in patients with chronic renal failure: possible degradation by the kidney.

Plasma immunoreactive (IR)-7B2 was measured in patients with chronic renal failure (CRF), using a specific radioimmunoassay. The mean (+/- S.E.M.) concentration of plasma IR-7B2 in CRF patients under hemodialysis (502 +/- 36 pg/ml, n = 27) was significantly higher than that in normal subjects (men, 52.9 +/- 1.7 pg/ml (n = 179); women, 55.8 +/- 1.3 pg/ml (n = 198]. Significant correlations between plasma levels of IR-7B2 and those of blood urea nitrogen, creatinine and beta 2-microglobulin were evident in non-dialyzed CRF patients. In the analyses of pooled plasma and urine obtained from normal subjects on gel permeation chromatography, a major peak of IR-7B2 was observed at an apparent molecular weight of 20,000 in the plasma, and at a position of a smaller molecular weight in the urine. These results suggest that 7B2 is degraded mainly in the kidney and that measurement of plasma 7B2 may serve as an appropriate tool for assessing renal function.