Renal degradation of insulin in patients with renal hypertension.

Renal processing of insulin was studied over plasma insulin levels of 5-80 mU/l by renal vein catheterization in 14 patients. Kidneys of patients with a normal GFR removed around 30% of the insulin from arterial plasma. In 6 patients having unilateral renal artery stenosis but only moderately impaired renal blood flow and unchanged PAH-extraction, a higher or unchanged fractional insulin extraction was seen in all but one, compared with the contralateral kidney. Due to the high fractional extraction of insulin by the kidneys with renal artery stenosis, a preserved total insulin uptake by these kidneys was seen. In 4 patients with renal hypoplasia (2 of them had renal artery stenosis) low values for insulin extraction and insulin uptake were seen on the affected side. One patient with chronic pyelonephritis and uremia had an extremely low renal insulin extraction and uptake. The results suggest that estimation of renal insulin extraction may be an important renal functional test in renovascular patients.