Endocrine Abstracts

Case: A 36-year-old gentleman presented with two month history of severe headaches, vomiting, polyuria and polydipsia. He reported profound episodic sweating especially on exertion and gradual weight loss. He was hypertensive (220/110 mmHg) at presentation. He had no palpitations, anxiety, dizziness, flushing or pallor. He had no diarrhoea or abdominal pain. His only family history was of Type 2 diabetes mellitus.

Investigation: Biochemical investigations showed glucose (23 mmol/l), ketones (3.3 mmol/l), and mild acidosis (pH 7.32). A diagnosis of DKA was made and treatment initiated. At this point investigations for secondary hypertension demonstrated elevated urinary and plasma Normetanephrine 4786 pmol/l (120–1180). He had a normal response to overnight dexamethasone suppression test. A diagnosis of a phaeochromocytoma/paraganglioma was biochemically suspected and a CT-abdomen showed a 6 cm left retroperitoneal necrotic lesion and NM-MIBG (123) scan was consistent with a MIBG-avid left adrenal lesion.

Treatment: A laparoscopic left adrenalectomy was performed following adequate alpha and beta blockade. Histopathology demonstrated a paraganglioma (positive for chromogranin and synaptophysin, and negative for inhibin and melan-A) with a PASS score of 11/20. Genetic testing confirmed an heterozygous mutation for C.689G>A,p(Arg 230His) of SDHB gene. Unfortunately on follow up scan a new Rib deposit was identified as well as a carotid body tumour. From a diabetes perspective he was started on insulin, but interestingly, when he was started on alpha and beta blockade, his glycaemic control improved: he stopped his prandial insulin and remained on a low dose of basal insulin. At presentation, his fasting C-peptide (89 pmol/l) was low with a glucose of 7.2 mmol/l supported a diagnosis of type 1 diabetes mellitus. However his anti-GAD, anti-IA2 and anti-islet cell antibodies were negative and his HbA1c was 11%. Four months after the removal of his tumour he developed hypoglycaemia and his insulin injections were stopped. His HbA1c normalised as well as his C-peptide suggesting that the initial DKA was as a result of excess catecholamines. Glycaemic indices have started to rise again now when a new likely metastatic deposit has been identified.

Conclusion: Diabetic ketoacidosis as first presentation of a paraganglioma is extremely rare. This case demonstrates the importance of evaluation of secondary causes of hypertension in young patients even in the setting of DKA. In our case, it led to early identification of a tumour with malignant propensity and possible marker for follow up.