Coexistence of TSH-secreting pituitary adenoma and autoimmune hypothyroidism.

Abstract

OBJECTIVE:

TSH-secreting pituitary adenomas account for about 1-2% of all pituitary adenomas. Their diagnosis may be very difficult when coexistence of other diseases masquerades the clinical and biochemical manifestations of TSH-hypersecretion.

CLINICAL PRESENTATION:

A 41-yr-old female patient, weighing 56 kg, was referred for evaluation of an intra- and suprasellar mass causing menstrual irregularities. Eight yr before, the patient had been given a diagnosis of subclinical autoimmune hypothyroidism because of slightly elevated TSH levels and low-normal free T4 (FT4). Menses were normal. Despite increasing doses of levo-T4 (L-T4; up to 125 microg/day), TSH levels remained elevated and the patient developed mild symptoms of hyperthyroidism. After 7 yr, the menstrual cycle ceased. Gonadotropins were normal, whereas PRL level was elevated at 70 microg/l and magnetic resonance imaging (MRI) of the hypothalamic- pituitary region revealed a pituitary lesion with slight suprasellar extension. The tumor was surgically removed and histological examinations revealed a pituitary adenoma strongly positive for TSH. Three months after surgery the patient was well while receiving L-T4 75 microg/day and normal menses had resumed. MRI of the hypothalamic-pituitary region showed no evidence of residual tumor. At the last follow-up, 16 months after surgery, serum TSH, free T3 (FT3), and FT4 levels were normal.

CONCLUSIONS:

Coexistence of autoimmune hypothyroidism and TSH-secreting pituitary adenoma may cause further delays in the diagnosis of the latter. In patients with autoimmune hypothyroidism, one should be aware of the possible presence of a TSH-secreting pituitary adenoma when TSH levels do not adequately suppress in the face of high doses of L-T4 replacement therapy and elevated serum thyroid hormone levels.

• Authors: M Losa, P Mortini, R Minelli, M Giovanelli
• Journal: Journal of endocrinological investigation (J Endocrinol Invest) Vol. 29 Issue 6 Pg. 555-9 (Jun 2006) ISSN: 0391-4097 [Print] Italy
• PMID: 16840835 (Publication Type: Case Reports, Journal Article)

Chemical References

• Thyrotropin
• Thyroxine

Topics

• Adenoma (complications, metabolism)
• Adult
• Autoimmune Diseases (complications)
• Female
• Humans
• Hypothyroidism (complications)
• Menstruation Disturbances (etiology)
• Pituitary Neoplasms (complications, metabolism)
• Thyrotropin (metabolism)
• Thyroxine (blood)