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Pituitary gland in hypothyroidism. Histologic and immunocytologic study
Archives of Pathology & Laboratory Medicine
|June 1, 1985
Summary
Primary hypothyroidism causes thyrotropic cell hyperplasia in the pituitary gland. This hyperplasia may progress to adenoma formation, particularly with insufficient thyroid hormone replacement therapy.
Area of Science:
- Endocrinology
- Pituitary Pathology
- Thyroid Disorders
Background:
- Primary hypothyroidism is linked to thyrotropic cell changes.
- Thyroid-stimulating hormone (TSH)-producing pituitary adenomas occur in various thyroid states.
- The link between thyrotropic hyperplasia and adenoma development is unclear.
Purpose of the Study:
- To investigate pituitary gland changes in patients with long-standing primary hypothyroidism.
- To characterize thyrotropic cell alterations concerning disease duration, severity, and therapy.
- To explore the development of thyrotropic adenomas in this context.
Main Methods:
- Histologic and immunocytologic examination of 64 pituitary glands.
- Assessment of thyrotropic cell hyperplasia, nodularity, and adenoma formation.
- Correlation of findings with clinical data on hypothyroidism duration, severity, and treatment.
Main Results:
- Diffuse thyrotropic cell hyperplasia occurred in 69% of glands; nodular hyperplasia in 25%.
- Greater hyperplasia correlated with less thyroid hormone replacement therapy.
- Tumorlets (12%) suggested an intermediate stage to microadenoma; 12 adenomas were found (5 TSH-reactive).
- Lactotropic hyperplasia was observed in 20% of patients, with an unknown mechanism.
Conclusions:
- Long-standing primary hypothyroidism induces significant thyrotropic cell hyperplasia.
- Inadequate thyroid hormone replacement therapy is associated with increased thyrotropic hyperplasia.
- Thyrotropic hyperplasia may represent a precursor to TSH-producing pituitary adenomas.