The prevalence of structural pituitary abnormalities by MRI scanning in men presenting with isolated...

Hypogonadotrophic hypogonadism (HH) is commonly associated with ageing, obesity and type 2 diabetes. The indications for pituitary imaging are controversial, and current guidelines are based on small case series.

Retrospective case series from a secondary/tertiary endocrinology referral centre.

All men presenting to the Edinburgh Centre for Endocrinology and Diabetes with hypogonadotrophic hypogonadism (testosterone <10 nmol/l and normal prolactin) from 2006 to 2013, in whom pituitary MRI was performed (n = 281). All HH patients referred in 2011 (n = 86) were reviewed to assess differences between those selected for pituitary MRI and those who were not scanned.

Pituitary MRI was normal in 235 men (83·6%), with 24 microadenomas (8·5%), 5 macroadenomas (1·8%) and 1 craniopharyngioma (0·4%) identified. The remaining 16 (5·7%) comprised a range of minor pituitary abnormalities including small cysts and empty sella. All men with abnormal imaging studies had otherwise normal pituitary function. Imaging abnormalities were associated with a significantly lower age at presentation (50 vs 54 years, P = 0·02), but no differences in testosterone or gonadotrophin levels were observed. Current Endocrine Society guidelines would have prompted imaging in only three of six patients with significant pituitary pathology.

Structural pituitary disease is more common in isolated HH than in the general population, and current guidelines do not accurately identify 'at-risk' individuals. Full anterior pituitary function testing has a low yield in patients presenting with hypogonadism. The optimal strategy for determining the need for pituitary imaging remains uncertain.