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Tests of adrenal insufficiency
J C Agwu1, H Spoudeas, P C Hindmarsh
1Sandwell NHS Trust, Hallam Road, West Bromich, West Midlands, B71 4HJ, UK.
Archives of Disease in Childhood
|March 23, 1999
Summary
The low dose Synacthen test (LDST) detects mild adrenal insufficiency missed by the standard short Synacthen test (SSST). A single 8 AM serum cortisol measurement has limited diagnostic value for adrenal insufficiency.
Area of Science:
- Endocrinology
- Clinical Diagnostics
Background:
- Assessing the hypothalamo-pituitary-adrenal axis in suspected adrenal insufficiency is clinically significant.
- The optimal diagnostic test remains a subject of debate among clinicians.
Purpose of the Study:
- To compare the diagnostic efficacy of the standard short Synacthen test (SSST), low dose Synacthen test (LDST), and 8:00 AM serum cortisol levels.
- To evaluate the sensitivity and specificity of these tests in patients with symptoms suggestive of adrenal insufficiency.
Main Methods:
- 32 patients with suspected adrenal insufficiency underwent SSST and LDST.
- Serum cortisol levels were measured at 8:00 AM.
- Normal response criteria included a peak serum cortisol >/= 500 nmol/l and/or an incremental concentration >/= 200 nmol/l.
Main Results:
- The LDST identified mild adrenal insufficiency in 8 patients not detected by the SSST.
- Three patients with abnormal responses to both tests had 8:00 AM cortisol < 200 nmol/l.
- An 8:00 AM serum cortisol cutoff of 500 nmol/l showed 100% sensitivity but only 33% specificity compared to the LDST.
Conclusions:
- The LDST is more sensitive than the SSST for detecting mild adrenal insufficiency.
- A single 8:00 AM serum cortisol measurement has limited utility in diagnosing adrenal insufficiency.