Endocrine Abstracts

A 64-year-old Sri Lankan female was admitted with a 1 week history of vomiting and poor oral intake. She had an episode of pneumonia 4 months previously and reported headaches, weight loss and dizziness since then.

On admission, her blood tests showed marked hyponatraemia with a sodium of 118 mmol/l and low serum osmolality of 243 mOsm/kg. A short synacthen test confirmed adrenal insufficiency and thyroid function tests showed secondary hypothyroidism despite being on levothyroxine for previously diagnosed hypothyroidism (TSH, 0.2 mU/l and Free T4, 7.1 pmol/l). Her prolactin and IGF1 levels were normal. Her gonadotrophins were low for a post-menopausal female (LH- 0.7 IU/l, FSH- 8.4 IU/l).

She was started on hydrocortisone, followed by up-titration of her levothyroxine which improved her symptoms and biochemistry.

She underwent an MRI pituitary; this showed the gland to be normal in size/structure, however, the pituitary appeared bright. A subsequent CT Brain/Pituitary showed small plaques of dural calcification which were within normal limits; there were no signs of calcification of the pituitary or brain substance. Other investigations, including a CT Thorax for possible granulomatous disease proved unremarkable.

Manganese is a paramagnetic substance; given the hyperintensity seen on MRI we were advised to check manganese levels. Interestingly, this was elevated at 391.5 nmol/l (RR: 72.8 – 218.5 nmol/l), suggesting hypopituitarism secondary to manganese toxicity.

Discussion: Heavy metal toxicity is a rare cause of neurological disorders and an even rarer cause of pituitary dysfunction, with the exception of iron. Classically, manganese toxicity causes features resembling Parkinson’s disease and arises from environmental/industrial overexposure, and is seen more commonly in groups such as miners and welders. Contaminated water wells and haemodialysis are also recognised causes. Much is yet to be understood about manganese homeostasis and toxicity; we present a case of hypopituitarism, a feature that has not previously been described in literature.