Endocrine Abstracts

Background: In clinical practice there is considerable confusion as to whether pituitary imaging is indicated in patients presenting with a marginally elevated serum prolactin level (<1000 milliunits per litre) and no other discernible cause of hyperprolactinaemia.

Objective: The aim of this study was to investigate the frequency of radiological abnormalities of the pituitary in patients presenting with marginal hyperprolactinaemia (<1000 milliunits per litre) and no other cause of this abnormality.

Methods: All the patients who presented to our Department between January 1998 and June 2003 and were diagnosed with prolactinoma or idiopathic hyperprolactinaemia were studied.

Results: 64 patients were identified. 34 (32 females) had microprolactinoma [aged 30.9±10.3 years (range 16-67)], 18 (11 males) had macroprolactinoma [aged 41.5±17 years (range 16-78)] and 12 (10 females) had idiopathic hyperprolactinaemia [aged 38±10.3 years (range 26-49)]. Prolactin values at diagnosis in microprolactinomas were 1954.6±1687.7 milliunits per litre (range 630-9680, in macroprolactinomas 42592.2± 63430.2 (range 1098-237000) and in idiopathic hyperprolactinaemia 1351.8±503.6 (range 886-2522). 29.4% of the patients with microprolactinomas had prolactin values <1000 and presented with hypogonadism (40% of them had also galactorrhoea). A focal hypointense lesion within the pituitary on T1 weighted MRI images was identified in 9 of these cases, whereas in the other one gland asymmetry and stalk deviation was found. Prolactin values <1000 were found in no patient with macroprolactinoma and in 33.3% of the patients with idiopathic hyperprolactinaemia, 75% of which presented with hypogonadism and 25% with galactorrhoea. Overall, in 71.4% of the patients presenting with prolactin values <1000 a lesion in the pituitary was identified.

Conclusion: Radiological abnormalities occur frequently in patients with clinical features of hyperprolactinaemia and marginally elevated prolactin values. In such cases pituitary imaging is indicated.