Pituitary apoplexy presenting with anorexia and hyponatraemia.

Pituitary apoplexy, a syndrome caused by haemorrhage into the pituitary gland, typically manifests as sudden severe headache, visual symptoms and hypopituitarism, including adrenal insufficiency. We report a case of a 65-year-old man with adrenal insufficiency due to pituitary apoplexy presenting with anorexia following temporal headache and diagnosed through evaluation for hyponatraemia. MRI focusing on the pituitary gland helped to confirm the diagnosis. Our experience serves as a useful reminder of this atypical presentation of pituitary apoplexy, also known as 'subclinical pituitary apoplexy,' and underscores the importance of careful evaluation for hyponatraemia using serial urine osmolality, which is useful to distinguish hypovolaemic hyponatraemia from euvolaemic hyponatraemia. Clinicians should consider pituitary apoplexy as a differential diagnosis in cases of anorexia, loss of energy or hyponatraemia, following headache even when the patient is lacking classical symptoms such as severe headache or visual symptoms.