Rare Central Hypothyroidism, But What is the Cause?

The male patient from an endemic goiter area of eastern Europe, sees me for a goiter.
The goiter is multinodular, but no Ultrasound suspicious nodules, and all below 10 mm.
No history of radiation exposure.

He is thin, and has muscle weakness. He complains of fatigue. His wife states he has had decreased libido since 1 1/2 years ago.

He has a multinodular goiter, and a BP 100/70. Normal pubic and axillary hair.
Normal male genitalia.

Prior testing 1, and 2 years ago by an internist had euthyroid FT4I and TSH, but lower
level Testosterone with low FSH/LH . a prolactin was also normal. He had a low normal repeat Testosterone one year ago.


FT4 0.6 TSH 2.9 Free T4 by dialysis 0.6.
Repeat FT4 0.3 TSH 0.69

The Head MR revealed a pituitary tumor. This non-cancerous tumor is replacing the normal pituitary gland. It is 3 cm in size. It is the cause of a rare cause of hypothyroidism.
Secondary hypothyroidism due to pituitary failure, caused by the tumor compressing the normal gland, and causing decreased TSH secretion. The patient is on the way to consultations to determine what the best therapy is for his tumor.

It is rare to see this , but the clues are low T4 with inapproprate normal TSH.
The free T4 by dialysis confirmed hypothyroidism, and the failure to see a rise in TSH as is usual with primary thyroid failure, was a major clue. The clincher was the wife's statement he had recent onset of decreased libido.
Also he had sexual problems and flabby muscle and weakness.

Beware of abnormal thyroid tests that do not match.
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