Tamm-Horsfall protein: are serum levels a marker for urinary tract obstruction?

Tamm-Horsfall protein (THP) has been found in the renal interstitium in patients with obstructive uropathy. The aim of this study was to investigate whether serum concentrations of THP could serve as a screening test for urinary tract obstruction. The presence of THP in normal human serum was confirmed by sodium dodecyl sulphate polyacrylamide gel electrophoresis and Western blotting. A specific enzyme immunoassay was then used to measure the serum concentration of THP. Serum THP concentrations were estimated in a cross-sectional study of a group of 23 patients who had technetium-99m-diethylene-triaminepenta-acetic acid (DTPA) nuclear urinary excretion studies to define urinary tract obstruction, and in longitudinal studies in 2 patients who developed acute bilateral ureteric obstruction following operations for ureteric reimplantation. The subjects with DTPA-proven urinary tract obstruction had higher concentrations of serum THP (n = 10, median = 43.9 ng/ml, range 10.4-152.1 ng/ml) than those who did not have obstruction (n = 13, median = 9.6 ng/ml, range 1.26-61.9 ng/ml). While this difference was significant (P < 0.01, Mann-Whitney U test), 6 of the 10 patients with obstruction had serum THP concentrations within the range of those patients without obstruction. The patients who developed acute bilateral ureteric obstruction both had increases in serum THP concentrations with obstruction and decreases in serum THP concentrations following relief of obstruction. These changes paralleled those in serum creatinine. The studies indicate that urinary tract obstruction results in increases in serum THP concentrations but these changes are not sufficient in magnitude to allow screening of children for urinary tract obstruction.