J Korean Soc Endocrinol.  1996 Jun;11(2):199-206.

A Case of Pituitary Feedback Adenoma Caused by Primary Hypothyroidism

• Yoo SJ
• Chang SA
• Ahn YB
• Son HS
• Yoon KH
• Kang MI
• Cha BY
• Lee KW
• Son HY
• Kang SK
• Chung MH

Abstract

A 14-year-old girl presented with severe headache and grand mal seizure. A magnetic resonance imaging(MRI) of brain showed a pituitary mass(1.0X1.5X1.3cm) incidentally during seizure evaluation. On physical examination, nodular goiter was detected on her anterior neck. The hormone study showed markdly increased basal thyroid stimulating hormone(TSH) level compared to thyroid hormone level, hyperprolactinemia and decreased basal growth hormone level. TSH and prolactin showed exaggerated response to thyrotropin releasing hormone(TRH) and the growth hormone showed delayed and blunted response to insulin-induced hypoglycemia. With the results of thyroid autoantibody and thyroid scan, the diagnosis of Hashimoto's thyroiditis was possible. Thyroid hormone and anticonvulsant drug were started with close observation of clinical status under the impression of pituitary feedback adenoma caused by hypothyroidism. After 3 months replacement therapy of levothyroxine sodium, she achieved euthyroid state with disappearance of headache and nodular goiter. After continuous replacement therapy for 9 months more, the pituitary mass was successfully regressed on follow up MRI with normalization of basal prolactin level. Grand mal seizure was developed after withholding anticonvulsant drug even though continuous admmistration of thyroid hormone. Because of similarity among pituitary adenoma discovered incidentally, careful hormonal study and high index of suspicion should be maintained to achieve correct diagnosis in order to avoid unnecessary pituitary surgery in these patients.

MeSH Terms

Adenoma*
Adolescent
Brain
Diagnosis
Female
Follow-Up Studies
Goiter, Nodular
Growth Hormone
Headache
Humans
Hyperprolactinemia
Hypoglycemia
Hypothyroidism*
Magnetic Resonance Imaging
Neck
Physical Examination
Pituitary Neoplasms
Prolactin
Seizures
Thyroid Gland
Thyroiditis
Thyrotropin
Thyroxine
Growth Hormone
Prolactin
Thyrotropin
Thyroxine