A study of Tamm-Horsfall protein excretion in hypertensive patients and type 1 diabetic patients

The study was performed in order to evaluate to what extent hypertension or diabetes mellitus may affect the urinary excretion rate of Tamm-Horsfall protein.

The urinary excretion rates of albumin and Tamm-Horsfall protein, a measure of glomerular and distal tubular function, respectively were measured in patients with essential hypertension (n = 17) and in type 1 diabetes with (n = 20) or without nephropathy (n = 8) and in apparently healthy subjects (n = 10).

Mean 24-h ambulatory blood pressure measurements showed higher blood pressure levels in the hypertensive (167/ 106 mmHg, p < 0.001) than in the diabetic patients with (136/84 mmHg) and without nephropathy (121/74 mmHg) and in healthy subjects (122/76 mmHg). Day and night ratios of systolic and diastolic blood pressure levels were not different among the four groups. Urinary albumin excretion rate was increased in patients with hypertension (30.8 x/ 3.4 microg/min; geometric mean x/tolerance factor; p < 0.001) and diabetes with nephropathy (462 x/ 3.5 microg/min; p < 0.001) compared with diabetic patients without nephropathy and healthy subjects (4.6 x/ 1.9 and 3.7 x/ 1.5 microg/min, respectively). The Tamm-Horsfall protein excretion rate was decreased in patients with diabetic nephropathy (11.6 x/ 3.5 microg/min) compared to patients with hypertension (36.3 x/2.1 1g/min; p < 0.01), diabetes without nephropathy (39.2 x/ 2.0 microg/min; p < 0.05) and healthy subjects (63.0 x/ 1.4 microg/min; p < 0.001), whereas no differences were found among the latter three groups.

These data indicate that high blood pressure may be associated with albuminuria, while a decrease in excretion rate of Tamm-Horsfall protein may be associated with diabetic nephropathy. These associations need to be studied in a larger population.