A 36 year old gentleman presented to Accident and Emergency with 2 day history of generalised headache associated with dizziness. No significant previous medical history.
Clinical examination: Alert, Oriented, Apyrexial, Pulse 80/mt regular, Blood pressure 132/70 with no postural drop. Systemic examination revealed no significant abnormality.
Investigations and management: Full blood count, Glucose, Urea and Electrolytes, Liver function tests, C-reactive protein, ESR were all normal. Adjusted serum calcium was 2.74 mmol/l (2.202.60). ECG was normal. CT Brain was normal. Headache and dizziness resolved after 2 days with analgesia. Because of high serum calcium further investigations were done.
Further investigations and management: Serum PTH 4.1 pmol/l (1.16.9). Myeloma screening was negative. Early morning serum cortisol less than 50 nmol/l (140500). ACTH less than 1.1 pmol/l (2.011.0). Prolactin, Growth hormone, Testosterone, LH, FSH were all normal. Short synacthen test showed suboptimal response of cortisol from less than 50 nmol/l to 410 nmol/l after 1 hour. Long synacthen test showed suboptimal response with peak cortisol 516 nmol/l. Insulin stress test showed no response of cortisol to hypoglycaemia. Growth hormone response to hypoglycaemia was adequate. TRH test, GNRH test were normal. 3×24 hour urinary catecholamines and Gut hormone profile were normal. Chest x-ray and MRI Brain including pituitary was normal. Repeat serum adjusted calcium was normal after 5 days. Further 2 repeat samples after 1 week were also normal. He is currently on 20 mg hydrocortisone daily in 2 divided doses of 15 and 5 mg.
Discussion: Isolated ACTH deficiency is very rare and usually presents with symptoms similar to Adrenal insufficiency. Case that is reported above is very atypical presentation and it is likely that it is diagnosed at early stage before developing classical symptoms.