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Answers on p 421.
A 70 year old man had been attending an outpatient clinic for investigation of diarrhoea, loss of appetite and weight loss, for which full clinical investigation (including duodenal and colonic biopsy series) had revealed no clear cause. Over a period of 10 years his weight had fallen from 82 kg to 64 kg. There was no history of vomiting. On this occasion he complained of dizziness, especially when he stood up. A slight postural fall in blood pressure was noted (120/70 to 105/70 mm Hg on standing) and a random serum cortisol was requested. This was reported as 27 nmol/l and he was admitted as an emergency for investigation.
He had been diagnosed as hypothyroid several years previously when his thyroid stimulating hormone (thyrotrophin) concentration had been 47 mU/l. Thyroxine replacement (150 μg/daily) had resulted in some amelioration of his diarrhoea (although he still required occasional loperamide) consistent with this being an uncommon manifestation of his hypothyroidism.1 He had also been investigated for a long standing (four year) normochromic normocytic anaemia and raised erythrocyte sedimentation rate for which no cause had been found. Ten years previously he had had problems with erectile failure which had not responded to papaverine and he had accepted that he would no longer have erections; testosterone and gonadotrophins at that time had been normal. He did not smoke or drink and had no cough or wheeze. There was no drug history other than those noted above.
On examination he was pale and thin with no goitre. There were no signs of hyperpigmentation. He was afebrile and some peripheral oedema was noted. His pulse was 74 beats/min and a postural fall was again observed (140/80 to 110/80 mm Hg). Laboratory investigations are shown in table 1.
A short tetracosactrin (as Synacthen; Novartis) test (250 μg tetracosactrin given intramuscularly) was undertaken; serum cortisol concentrations at 0, 30, and 60 mins after injection were 28, 87, and 120 nmol/l respectively.
- What is the differential diagnosis?
- What further investigations would you request?
- How would you manage the patient?
Answers on p 421.