Plasma levels of thyrotropin-releasing-hormone in various splanchnic, renal, suprarenal, and cerebral veins.

Endogenous TRH levels were determined in plasma obtained selectively via percutaneous transhepatic and femoral catheterization. TRH was measured using a very sensitive RIA method. In the pancreatic veins, internal jugular vein, left testicular vein, and other described veins, normal peripheral levels were found.