Utility of the Radioimmunoassay of Serum Thyrotrophin in Man

  1. JEROME M. HERSHMAN, M.D., F.A.C.P.; and
  2. JAMES A. PITTMAN, JR., M.D., F.A.C.P.
  1. Birmingham, Alabama

    Abstract

    The normal human serum thyrotrophin (TSH) measured by a double antibody radioimmunoassay was 3.9 ± 2.0 (SD) µunits/ml. It was markedly elevated in 61 patients with primary hypothyroidism and undetectable in 10 with hypothyroidism secondary to hypopituitarism and in 23 hyperthyroid patients. There was no significant diurnal variation of serum TSH and no increase after cold exposure of adult men for 1 hr or after electroconvulsive, vasopressin, or glucagon therapy. The level was normal in patients with Cushing's syndrome and acromegaly and in pregnant women at term. The serum TSH of newborns exceeded the maternal level significantly and rose to very high values at 1 hr of age. Because of the stability of serum TSH levels in adults, an elevated level is good indication of primary hypothyroidism. Injection of synthetic thyrotrophin-releasing factor (500 to 1,000 µg) caused marked elevation of serum TSH; the response to 10 mg given orally was more prolonged. Synthetic thyrotrophin-releasing factor should be a useful agent for clinical assessment of pituitary TSH reserve.

    Article and Author Information

    • ▸From the Metabolic Research and Nuclear Medicine Laboratories, Veterans Administration Hospital, and the Division of Endocrinology and Metabolism, Department of Medicine, University of Alabama School of Medicine, Birmingham, Ala.

    • *Kindly provided by Ayerst Laboratories, New York, N.Y.

    • Supported in part by Veterans Administration Part I Research Funds and research grants AM 09599, AM 12044, 5 MO1-RR32, and T1-AM-5053, U.S. Public Health Service, Washington, D.C.

    • ▸Requests for reprints should be addressed to Jerome M. Hershman, M.D., VA Hospital, 700 S. 19th St., Birmingham, Ala. 35233

      • Received November 18, 1970.
      • Accepted January 12, 1971.
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