From the Guidelines
An ACTH level of 8 pg/mL is within the normal reference range, which typically spans from 7-69 pg/mL, so it is not considered low. Your morning cortisol level of 13.3 μg/dL is also within normal limits, as morning cortisol typically ranges from 5-25 μg/dL. These values suggest your hypothalamic-pituitary-adrenal (HPA) axis is functioning normally. The relationship between ACTH and cortisol is important - ACTH is produced by the pituitary gland and stimulates the adrenal glands to produce cortisol. When these values are proportionate to each other, as yours appear to be, it indicates proper feedback regulation. If you're experiencing symptoms that prompted these tests (such as fatigue, weight changes, or mood disturbances), it would be worth discussing with your healthcare provider as these symptoms could be related to other conditions despite normal ACTH and cortisol levels, as suggested by 1. Regular follow-up with your healthcare provider is recommended if you have ongoing concerns. In the context of adrenal insufficiency diagnosis and management, the guidelines from 1 emphasize the importance of considering the clinical presentation and laboratory results together, but in your case, the ACTH and cortisol levels do not indicate adrenal insufficiency. It's also important to note that the provided evidence from 1 and 1 focuses on the management of adrenal insufficiency and the diagnosis of primary adrenal insufficiency, but your test results do not align with these conditions. Therefore, your current ACTH and cortisol levels do not necessitate intervention for adrenal insufficiency, but any persistent or concerning symptoms should be evaluated further by a healthcare provider.
From the Research
Adrenal Insufficiency Diagnosis
- The diagnosis of adrenal insufficiency can be challenging due to the rarity of the disease and limitations in biochemical assessment of cortisol status 2.
- A morning serum cortisol level >13 mcg/dL can reliably rule out adrenal insufficiency, and further evaluation with the cosyntropin stimulation test (CST) is needed for levels ≤13 mcg/dL 3.
Cosyntropin Stimulation Test
- The cosyntropin stimulation test is commonly performed in patients suspected of having adrenal insufficiency when basal serum cortisol levels are inconclusive 2.
- The test requires intravenous or intramuscular administration of cosyntropin and multiple blood draws, and a normal response reliably rules out primary adrenal insufficiency and moderately decreases the likelihood of secondary adrenal insufficiency 3.
Interpretation of Test Results
- The interpretation of the cosyntropin stimulation test results should take into consideration the clinical presentation and technical factors that can affect cortisol values and diagnostic accuracy 2.
- A threshold of 14.6 μg/dL for cortisol at 60 minutes after ACTH stimulation is recommended for the Abbott Architect immunoassay, which can help reduce false-positive results and misclassification of patients with suspected adrenal insufficiency 4.
Morning Serum Cortisol as a Screening Test
- Morning serum cortisol (MSC) can be used as a screening test for adrenal insufficiency, with a cutoff value of 234.2 mmol/L having a sensitivity of 83.3% and specificity of 89.1% 5.
- The use of MSC as a first-step diagnostic test can help omit the need for the short stimulation test in almost half of the cases, but prospective and longitudinal studies are needed to confirm the cutoff values proposed 5.