Endocrine Abstracts

Hypopituitarism usually is the result of a pituitary tumour or its treatment. If, however, pituitary imaging is negative then an alternative diagnosis should be sought. We present two patients initially diagnosed as idiopathic hypopituitarism in whom the underlying diagnosis was delayed with potentially serious consequences.

The first case was of a 32 year old male who presented with symptoms and signs of hypogonadism. Serum testosterone (<0.7 nmol/L) and gonadotrophins were low (FSH<0.5 U/L, LH<0.5 U/L) and prolactin was normal (118 mU/L). Thyroid function was normal (fT₄ 9.7 pmol/L; TSH 1.33 mU/L). He had a normal cortisol response (peak 1002 nmol/L) but abnormal growth hormone response to hypoglycaemia (8.1 mU/L). CT pituitary was normal. On gonadotrophin therapy he fathered two children. He then presented 5 years after diagnosis with congestive cardiac failure and ferritin was elevated at 6309 ug/L (18 – 325 ug/L). Genetic testing revealed the presence of TYR/TYR at position 282 confirming haemochromatosis as the cause of the heart and pituitary failure.

The second case was of a 51 year old female presented with nausea and general lethargy. Initial blood tests suggested hypopituitarism with low serum cortisol (<30 nmol/L), low free T₄ (6.9 pmol/L) and inappropriately normal TSH (2.3 mU/L). Prolactin was 1190 mU/L and gonadotrophins were appropriately post menopausal (FSH 26.6 U/L, LH 16.8 U/L). ITT confirmed an inadequate cortisol response (peak level<30 nmol/L). CT pituitary was normal. Four years later, investigation of abnormal liver function revealed a raised ferritin (389 ug/L) and the presence of CYS/TYR at position 282 confirmed the diagnosis of haemochromatosis.

Haemochromatosis causes pituitary dysfunction by depositing iron in the anterior pituitary. Imaging is usually normal and such patients are often wrongly labelled as having idiopathic hypopituitarism. Early diagnosis is important however as treatment may reverse the pituitary deficit and prevent future sequelae. We recommend that iron studies are performed on all patients who present with hypopituitarism and normal pituitary imaging.