Revisiting short synacthen test: Observational study of utilization of short synacthen test to diagnose adrenal insufficiency

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: SUN 50-71-HPA Axis
Sunday, June 16, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board SUN-61
Edwin Chng*, Stanley Lam, Robert Hawkins and Shaikh Abdul Shakoor
Tan Tock Seng Hospital, Singapore, Singapore
Introduction: The clinical presentation of adrenal insufficiency is highly variable, ranging from florid presentation to more insidious and vague symptoms. Hence, the diagnosis often depends on a high index of clinical suspicion. A short synacthen test (SST) is often used to diagnose adrenal insufficiency. However, there is a lack of studies on the use of this test in clinical practice and protocols vary widely; for example, some use only 30 minutes value in the diagnosis. Chronic steroid usage, particularly traditional Chinese medicine (TCM), is also very common in the local population, hence increasing the prevalence of hypocorticolism.

Method: The data for 123 patients in our tertiary hospital who underwent SST in the last 2 years was collected prospectively by interview and clinical notes.

Results and discussion: A total of 44 (35.8%) patients failed SST: 60min cortisol <20µg/dl (550nmol/L). Chronic steroid use (mostly TCM) is the commonest cause for failed SST (28/44, 63.6%) in our cohort. The percentage of important symptoms and signs in those who failed SST is as follows: weight loss (63.6%), fatigue (52.3%), giddiness (50.0%), hyponatraemia (35.0%) and postural hypotension (15.9%). However, positive predictive values for these symptoms and signs were quite low and not significant.

Our results also showed 52.0% of the patients failed the SST at 30min, compared to 35.8% who failed at 60min (p=0.01), suggesting that the use of a 30min cutoff may over-diagnose hypocortisolism. All patients with either a random or 8am cortisol ≥14.5µg/dl (400nmol/L), eventually passed SST, suggesting that these patients (15.2%) could have avoided an SST.

We observed a low usage of ACTH measurements in our clinical practice, and hence we are unable to draw any conclusion of its usefulness from our limited data. However, the combination of a robust cortisol and ACTH done at 8am could be very helpful in diagnosing adrenal insufficiency, and may reduce the frequency of SST in clinical practice.

Nothing to Disclose: EC, SL, RH, SA

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