The use of beta-subunits of gonadotrophin hormones in the follow-up of clinically non-functioning pituitary tumours.

Objective: Clinically nonfunctioning pituitary adenomas (NFA) are mostly of gonadotroph origin. However, increased levels of circulating hormones or subunits in patients with NFA usually do not cause clinical symptoms, nor are they used as biological tumour markers. In this study we assessed the value of measuring beta subunits of gonadotrophin hormones in the post-operative follow-up of patients bearing these tumours.

Design: Patients harbouring NFA were studied before and three months after transphenoidal pituitary surgery. beta-LH and beta-FSH levels were measured before and following TRH administration on the two occasions. Hormone levels were analyzed in relation to imaging studies performed before and after surgery.

Patients: Twenty four patients operated at the Tel Aviv-Sourasky Medical Centre for NFA.

Results: Pathological beta-FSH and beta-LH levels were detected in 79% and 60% of patients respectively. beta-LH levels decreased after surgery but there were no significant changes in beta-FSH levels. There was a tendency for tumours with high basal beta-LH levels to be larger and to have a poor surgical outcome. Normalization of beta-LH levels post-operatively was usually associated with a decrease in tumour mass or complete removal of the tumour. Persistent pathological responses of beta-LH to TRH after surgery were common in patients with residual tumours on imaging. Nevertheless there were exceptions to this pattern, rendering post-operative beta-LH levels insufficiently reliable as a marker for the presence of residual tumour.

Conclusion: Although there appears to be a relationship between beta-LH levels, tumour size and surgical outcome, this association is presently insufficient to allow the routine use of either basal or TRH induced beta-LH responses in the post-surgical follow-up of clinically nonfunctioning pituitary adenomas.