Thyroid-pituitary interaction: Feedback regulation of thyrotropin secretion by thyroid hormones

Journal Article · Thu Jan 07 00:00:00 EST 1982 · New Engl. J. Med.; (United States)

OSTI ID:5639427

Larsen, P R; Bleich, H L; Moore, M J

Thyroid-hormone regulation of TSH production involves a response to plasma concentrations of T4 and T3. A substantial fraction of intracellular T3 in the pituitary derives from the conversion of T4 to T3, and recent studies indicate that this process is physiologically regulated. Changes in pituitary conversion of T4 to T3 are often the opposite of those that occur in the liver and kidney under similar circumstances. The presence of this pathway for T3 production indicates that the pituitary can respond independently to changes in plasma levels of T4 and T3; in contrast, many tissues appear to be sensitive mainly to the plasma T3 concentration. Recent studies suggest that conversion of T4 to T3 in the cerebral cortex and cerebellum is also important in providing intracellular T3 to these particular tissues. Given these results, it is not suprising that a complete definition of thyroid status requires more than the measurement of the serum concentrations of thyroid hormones. For some tissues, among them the brain and pituitary, the intracellular T3 concentrations may only partly reflect those in the serum. Recognition that the intracellular T3 concentration in each tissue may be subject to local regulation and an understanding of the importance of this process to the regulation of TSH production shoul permit a better appreciation of the limitations of radioimmunoassay serum thyroid hormone and TSH levels. These concepts also provide a physiologic rationale for the use of thyroxine for replacement in hypothyroid patients or for TSH suppression.

• Research Organization: Brigham and Women's Hospital, Boston, MA
• OSTI ID: 5639427
• Journal Information: New Engl. J. Med.; (United States), Vol. 306:1
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
59 BASIC BIOLOGICAL SCIENCES
THYROXINE
RADIOIMMUNOASSAY
TRIIODOTHYRONINE
TSH
HOMEOSTASIS
DIAGNOSIS
DISEASES
EVALUATION
EXPERIMENTAL DATA
FEEDBACK
INTERACTIONS
PATIENTS
PITUITARY GLAND
THYROID
AMINO ACIDS
BODY
CARBOXYLIC ACIDS
DATA
ENDOCRINE GLANDS
GLANDS
HORMONES
INFORMATION
ISOTOPE APPLICATIONS
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC IODINE COMPOUNDS
ORGANS
PEPTIDE HORMONES
PITUITARY HORMONES
RADIOASSAY
THYROID HORMONES
TRACER TECHNIQUES
550601* - Medicine- Unsealed Radionuclides in Diagnostics
551000 - Physiological Systems