Endocrine Abstracts

Background: Prevalence of Addison’s disease (AD) among patients with Type 1 diabetes mellitus (T1DM) is estimated at 0.2%, whilst prevalence of T1DM among patients with AD can be up to 14%. Residual adrenal function in patients with established AD may be present in up to 30% of cases but its clinical significance is not fully clear.

Aims: To evaluate the prevalence of AD with preserved glucocorticoid function in patients with T1DM at Newcastle Diabetes Centre. To describe the demographics, clinical presentation and investigations that led to the diagnosis of AD with preserved glucocorticoid function in these patients.

Methods: Review of electronic records for patients with T1DM registered at our centre and diagnosed with AD and/or prescribed steroids and fludrocortisone regularly.

Results: 12 out of 2704 patients had a diagnosis of AD. The prevalence of AD in our T1DM population is 0.6%. 3/12 (25%) patients with AD demonstrated preserved or relatively preserved glucocorticoid function. All 3 patients had chronic, intermittent hyponatraemia with hyperkalaemia. Random cortisol level in 2 patients were 205 nmol/l and 479 nmol/l while the third patient was established on longterm immunosuppressant steroid therapy. The latter achieved a peak cortisol of 179 mmol/l on Short Synacthen Testing, suggesting preserved glucocorticoid function. None of the patients reported weight loss but fatigue was a commonly reported symptom.

Conclusions: AD with preserved glucocorticoid function, albeit a rare entity, is most likely to be encountered during routine follow-up in the T1DM clinic in patients with intermittent hyponatraemia or hyperkalaemia. Clinicians should be alert to investigate for AD in these patients. A random cortisol measurement may miss AD with preserved glucocorticoid function. In selected cases, clinicians should consider checking transtubular potassium gradients, serum bicarbonate, renin, aldosterone and ACTH levels, if short Synacthen test results are normal.