Urinary epidermal growth factor excretion is correlated to renal function loss per se and not to the degree of diabetic renal failure

Urinary epidermal growth factor (EGF) excretion is seen as a marker of tubular function, and some studies conclude that EGF excretion can already be reduced early in the development of diabetic renal disease. It is even suggested that EGF could play a role in kidney and glomerular enlargement and hypertrophy in diabetic subjects. We have investigated various groups of subjects, namely healthy controls (n = 5), patients with non-diabetic chronic renal insufficiency (n = 10), and normoalbuminuric (n = 9), microalbuminuric (n = 13) and nephropathic (n = 9) insulin-dependent diabetic subjects. In all subjects glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) were measured using a continuous infusion of 125I-iothalamate and 131I-hippuran, respectively. Diabetic subjects were tested during (near) normoglycaemic conditions. During the renal function test urine was collected for EGF measurement (in ng). With lower GFR values, EGF excretion/min was also lower. GFR correlated well with EGF/min (r = 0.63, p < 0.001). Fractional EGF clearance (EGF/GFR) was comparable in all groups. There was no correlation between urinary albumin excretion rate and EGF excretion in the diabetic subjects (r = -0.18, n.s.) and in all subjects (r = -0.12, n.s.). There was a significant correlation between UAER and GFR (r = -0.51, p < 0.005). No significant correlation could be found between urinary albumin excretion rate (UAER) and EGF/GFR (r = -0.07, n.s.).(ABSTRACT TRUNCATED AT 250 WORDS)