Excretion of human urinary kallikrein quantity measured by a direct radioimmunoassay of human urinary kallikrein in patients with essential hypertension and secondary hypertensive diseases.

Recently, we established a very sensitive, specific and simple direct radioimmunoassay method for human urinary kallikrein. In this study, in order to clarify whether or not the low or high excretion rate of urinary kallikrein activity in patients with essential hypertension, primary aldosteronism, pheochromocytoma and Bartter's syndrome is caused by changes in enzyme quantity, urinary kallikrein excretion was measured with this direct radioimmunoassay method in normal subjects and in patients with these diseases. Urinary kallikrein excretion measured as enzyme quantity was significantly lower in patients with essential hypertension, and higher in patients with primary aldosteronism and Bartter's syndrome. These results are consistent with other previously reported data and our data measured by means of esterase assay or kininogenase assay. The results also suggest that lowered or elevated excretion of urinary kallikrein activity in these diseases is caused, in part at least, by the lowered or elevated excretion of enzyme quantity.