Endocrine Abstracts

Background: There is no published guidance on when to request a pituitary MRI in hypogonadal men. The presence of low or low normal gonadotrophins is common in men with symptomatic testosterone deficiency and metabolic syndrome and/or type 2 diabetes. Our practise is to perform pituitary MRI scans in men with isolated hypogonadotrophic hypogonadism who have LH< 4 Iu/l.

Method: One hundred and eighty-one patients that had a pituitary MRI scan between January 2005 and October 2009 were identified using the hospital database. These patient’s notes were reviewed and those that had an MRI requested because of hypogonadotrophic hypogonadism but otherwise normal pituitary function were included (n=96). The MRI reports were reviewed to ascertain if there were any focal pituitary abnormalities.

Results: Mean age was 52 years (range 20–80). LH< 2 Iu/l n=37, LH 2–4 Iu/l n=49 and LH>4 Iu/l (4.1–7.9) n=10. Overall 15/96 (15.6%) patients had an abnormal scan of which LH<2 Iu/l 9/37 (25.7%) (3 pituitary cysts, 2 Rathke’s cysts, 3 empty or partially empty sella, 1 microadenoma); LH 2–4 Iu/l 5/49 (8%) (4 partially empty or empty sella, 1 microadenoma); LH >4 Iu/l 1/10 (empty sella LH 4.7 Iu/l). The mean total testosterone for subjects with abnormal scans was 7.38 nmol/l (2.2–11.1). An analysis of variance indicated no significant difference in levels of LH, FSH and age between patients with abnormal and normal scans.

Conclusion: A substantial proportion of the scans analysed contained abnormalities. No MRI scan identified a lesion which required interventional treatment of the structural abnormality. Some abnormalities may have been incidental findings however some give the patient a diagnosis. This shows that pituitary MRIs should be performed in men with below normal or low normal LH and remains a valuable diagnostic tool for patients with hypogonadotrophic hypogonadism. The lack of correlation with age, LH and FSH shows that these serve as poor indicators for pituitary disease in hypogonadotrophic hypogonadism.