Urinary excretion of Tamm-Horsfall protein in normotensive and hypertensive elderly patients.

Tamm-Horsfall protein (THP) is a glycoprotein that is exclusively produced by the kidney in the thick ascending limb of Henle's loop (TAHL). Disturbances of TAHL function are associated with decreased urinary THP excretion. It is well known that renal function declines with advancing age. Moreover, it is suggested that THP may play a role in the pathophysiology of hypertension. The aim of this study was to assess urinary excretion of THP (U-THP) in healthy and hypertensive elderly patients. Fifteen young healthy subjects (YHS), 15 young hypertensive patients (YHT), 15 older normotensive (>60 years) subjects (OHS) and 31 older (>60 years) hypertensive patients (OHT) were examined. In all subjects 24-h urinary volume (UV), U-THP and creatinine (U-Cr), specific gravity of urine (U-SG), serum creatinine (S-Cr), and mean arterial pressure (MAP) were assessed. THP urinary excretion was significantly decreased in normotensive elderly patients, but not in hypertensive ones. Higher U-THP in the elderly hypertensive as compared with the elderly normotensive patients seems to be more the consequence than the cause of arterial hypertension.