Renal tubular protein degradation of radiolabelled aprotinin (Trasylol) in patients with chronic renal failure.

ABSTRACT

1. The new method developed to measure renal tubular degradation of small filtered proteins in patients with normal renal function, using radiolabelled aprotinin (Trasylol) (R. Rustom, J. S. Grime, P. Maltby, H. R. Stockdale, M. Critchley, J. M. Bone. Clin Sci 1992; 83, 289-94), was evaluated in patients with chronic renal failure. 2. Aprotinin was labelled with either 99mTc (40 MBq) or 131I (0.1 MBq), and injected intravenously in nine patients, with different renal pathologies. 51Cr-EDTA clearance (corrected for height and weight) was 40 +/- 5.4 (range 11.2-81) ml min-1 1.73 m-2. Activity in plasma and urine was measured over 24-48 h, and chromatography on Sephadex-G-25-M was used to separate labelled aprotinin from free 99mTcO4- or 131I-. Renal uptake was measured for 99mTc-labelled aprotinin only. 3. The volume of distribution was 20.2 +/- 2.3 litres. Chromatography showed all plasma activity as undegraded aprotinin, and urine activity only as the free labels (99mTcO4- or 131I-). 4. As in patients with normal renal function, activity in the kidney appeared promptly, with 5.7 +/- 2.5% of the dose detected even at 5 min. Activity rose rapidly to 9.4 +/- 1.6% of dose after 1.5 h, then more slowly to 15.0 +/- 0.5% of dose at 4.5 h, and even more slowly thereafter, reaching 24.1 +/- 2.8% of dose at 24 h. Extra-renal uptake was again insignificant, and both 99mTcO4- and 131I- appeared promptly in the urine, with similar and uniform rates of excretion over 24 h.(ABSTRACT TRUNCATED AT 250 WORDS)