Acute effects of propylthiouracil (PTU) on thyroidal iodide organification and peripheral iodothyronine deiodination: correlation with serum PTU levels measured by radioimmunoassay

Journal Article · Thu Jan 01 04:00:00 EST 1981 · J. Clin. Endocrinol. Metab.; (United States)

OSTI ID:5574285

Cooper, D S ^[1]; Saxe, V C; Meskell, M; Maloof, F; Ridgway, E C

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1. Massachusetts General Hospital, Boston

Propylthiouracil (PTU) levels in serum have been measured by RIA in five normal volunteers and four patients with untreated Graves's disease. Peak PTU levels after 50, 200, and 300 mg PTU were 0.91 +/- 0.13, 2.9 +/- 0.6, and 4.0 +/- 0.6 ..mu..g/ml in the normal subjects and 1.04 +/- 0.1, 4.5 +/- 0.7, and 7.1 +/- 0.4 ..mu..g/ml in the hyperthyroid patients, respectively. Peak PTU levels and PTU area under the curve were significantly greater at the 300-mg dose (P < 0.01) in the hyperthyroid patients compared to the normal subjects. The effect of PTU on iodide organification was assessed by perchlorate discharge testing. Both the normals and the hyperthyroid patients had normal basal perchlorate-dischargeable /sup 123/I. Four hours after an oral dose of PTU, the hyperthyroid patients had a greater percentage of perchlorate-dischargeable /sup 123/I than the euthyroid controls (+38 +/- 5% vs. 13 +/- 2%; P < 0.02). There was a highly significant correlation between serum PTU levels and perchlorate-dischargeable iodide in both normals (r = 0.86; P < 0.001) and hyperthyroid patients (r = 0.83; P < 0.001). T/sub 3/ and rT/sub 3/ were measured serially over 24 h after single oral doses of 50, 200, and 300 mg PTU. In normal volunteers, serum T/sub 3/ declined slightly but significantly after the 200- and 300-mg doses; an increase in rT/sub 3/ was also noted, but the changes did not attain statistical significance. In the hyperthyroid patients, serum T/sub 3/ fell from 501 +/- 29 to 379 +/- 27 ng/dl after 50 mg PTU (P < 0.001), from 433 +/- 40 to 264 +/- 18 ng/dl after 200 mg PTU (P < 0.001), and from 463 +/- 40 to 335 +/- 18 ng/dl after 300 mg PTU (P < 0.05). Serum rT/sub 3/ rose after each dose: from 119 +/- 12 to 131 +/- 11 ng/dl (P = NS) after 50 mg PTU, from 113 +/- 11 to 146 +/- 12 ng/dl (P < 0.02) after 200 mg PTU,

• OSTI ID: 5574285
• Journal Information: J. Clin. Endocrinol. Metab.; (United States), Journal Name: J. Clin. Endocrinol. Metab.; (United States) Vol. 54:1; ISSN JCEMA
• Country of Publication: United States
• Language: English

Related Subjects

550601* -- Medicine-- Unsealed Radionuclides in Diagnostics
551000 -- Physiological Systems
59 BASIC BIOLOGICAL SCIENCES
62 RADIOLOGY AND NUCLEAR MEDICINE
AMINO ACIDS
ANTITHYROID DRUGS
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL EFFECTS
BIOSYNTHESIS
BLOOD SERUM
CARBOXYLIC ACIDS
DATA
DRUGS
EXPERIMENTAL DATA
HORMONE ANTAGONISTS
HORMONES
INFORMATION
INHIBITION
ISOTOPE APPLICATIONS
KINETICS
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC IODINE COMPOUNDS
PATIENTS
PEPTIDE HORMONES
RADIOASSAY
RADIOIMMUNOASSAY
REACTION KINETICS
SYNTHESIS
THYROID HORMONES
THYROXINE
TRACER TECHNIQUES
TRIIODOTHYRONINE