Circulating somatomedin activity and sulfate levels in adults with normal and impaired kidney function.

Circulating somatomedin activity was measured by porcine cartilage bioassay in 52 men with normal and impaired renal function. Serum somatomedin activity correlated inversely with serum creatinine and urea nitrogen, and was significantly decreased in nondialyzed patients with advanced renal failure. Somatomedin activity was even lower in subjects undergoing maintenance hemodialysis, but increased significantly during a single dialysis. Serum inorganic sulfate was elevated in uremic individuals, correlated directly with creatinine and urea nitrogen, and fell with dialysis. Since somatomedins measured by radioassay are reported to be elevated in uremia and do not change during hemodialysis, it seems likely that bioassayable somatomedin activity is depressed because of the accumulation of dialyzable inhibitors. Since somatomedins have broad anabolic properties, impaired somatomedin action may contribute to poor growth and wasting in uremia.