Urinary Tamm‐Horsfall Glycoprotein Concentrations in Normal and Urolithiasis‐Affected Male Cats Determined by an ELISA

Summary A precise and reproducible enzyme‐linked immunosorbent assay (ELISA) which measures urinary cat Tamm‐Horsfall glycoprotein (cTHP) was developed in order to investigate the possible role of cTHP in the pathogenesis of feline urolithiasis. Reproducible quantification required that the cTHP be disaggregated with 2M urea and 0.05% Tween 20. It was necessary to standardize rigidly the handling of the samples prior to analysis, since the apparent cTHP concentration varied depending on the preanalysis protocols. Using the sample handling protocol of freezing urine at −70 °C before dialysis, urinary cTHP was quantified in male cats with no history of urolithiasis (“normal” cats) and in male cats with a history of urolith formation (“urolithiasis” cats). The mean cTHP concentration in adult, male “normal” cats of 49.2 ± 35.5 μg/ml (N = 23) was significantly lower than the mean cTHP concentration of 95.4 ± 34.1 μg/ml (N = 9) in “urolithiasis” cats (p <0.01, Students' T‐test). These findings indicate a correlation between urolithiasis and high urine cTHP concentrations in male cats which warrants further investigation.