Radioimmunoassay of thyrotropin releasing hormone in plasma and urine.
A sensitive and specific radioimmunoassay has been developed capable of measuring thyrotropin releasing hormone (TRH) in extracted human plasma and urine. All of three TRH analogues tested had little cross-reactivity to antibody. Luteinizing hormone releasing hormone, lysine vasopressin, rat growth hormone and bovine albumin were without effect, but rat hypothalamic extract produced a displacement curve which was parallel to that obtained with the synthetic TRH. Sensitivity of the radioimmunoassay was 4 pg per tube with intraassay coefficient of variation of 6.2-9.7%. Synthetic TRH could be quantitatively extracted by methanol when added to human plasma in concentration of 25, 50 and 100 pg/ml. TRH immunoreactivity was rapidly reduced in plasma at 20 degrees C than at 0 degrees C, but addition of peptidase inhibitors, FOY-007 and BAL, prevented the inactivation of TRH for 3 hr at 0 degrees C. The TRH in urine was more stable at 0 degrees C than 20 degrees C, and recovered 75 +/- 4.6% hr after being added. The plasma levels of TRH were 19 pg/ml or less in normal adults and no sex difference was observed. The rate of disappearance of TRH administered i.v. from the blood could be represented as half-times of 4-12 min. Between 5.3-12.3% of the injected dose was excreted into urine within 1 hr as an immunoreactive TRH. These results indicate the usefulness of TRH radioimmunoassay for clinical investigation.
D000293:Adolescent; D000328:Adult; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology; D006801:Humans; D006980:Hyperthyroidism / Q000097:blood / Q000652:urine; D008236:Lypressin / Q000494:pharmacology; D008297:Male; D008875:Middle Aged; D011863:Radioimmunoassay / Q000379:methods*; D012710:Serum Albumin, Bovine / Q000494:pharmacology; D013973:Thyrotropin-Releasing Hormone / Q000032:analysis* / Q000097:blood / Q000652:urine
D012710:Serum Albumin, Bovine; D007987:Gonadotropin-Releasing Hormone; D008236:Lypressin; D013973:Thyrotropin-Releasing Hormone