Endocrine Abstracts

A 43-year-old, previously well Asian male was found to have a large intrasellar mass when investigated with an MRI brain for a history of reduced hearing. He had no other clinical history. His visual fields were normal. The tumour had extended to the suprasellar cistern but there was no optic nerve compression. Pre-operative biochemistry showed mild panhypopituitarism with a 0900 a.m. cortisol of 135 mmols/l, a free T₄ of 8.5 pmols/l, a free T₃ of 3.2 pmols/l, a TSH of 3.2 mU/l, a total testosterone of 5.6 nmols/l and a prolactin of 732 IU/l. The tumour was resected transsphenoidally. Histology revealed a pituitary adenoma. Histochemistry for hormones ACTH, prolactin and TSH was negative. Post-operative recovery was uneventful; he was commenced on Hydrocortisone, which was phased out 3 months later, and endocrine reassessment undertaken. LH and FSH levels were noted to be high at 11.1 IU/l (normal 0.8–7.6 IU/l) and 116 IU/l (normal 0.7–11 IU/l) respectively with a free testosterone of 7.2 pg/ml. Further histochemistry was requested for FSH and LH which showed heavy staining for FSH but no staining for LH. A repeat MRI showed substantial residual tumour. FSH levels remained high, 121IU/l eight months after the surgery. The patient underwent repeat transshenoidal surgery 12 months after the first surgery. His FSH reduced to 23.5 IU/l 24 h after the surgery and was 24.7 IU/l ten months later. He was clinically well on hydrocortisone, thyroxine and testosterone replacement.

Although a significant percentage of non-functioning pituitary adenomas stain positively for LH and alpha and beta subunits of FSH in vitro, increased levels of circulating FSH and LH are very rare and account for only 10–15% of gonadotrophic adenomas. In our case, FSH levels were helpful in early detection of residual tumour and assessing completeness of resection following repeat surgery