Assessing Adrenal Suppression while on Steroids

Assessing adrenal function is challenging because false positives and false negatives in the testing is common, particularly when a patient is actively receiving steroids.

A high-normal serum cortisol essentially rules out adrenal suppression. However, normal values, even in the morning, are inconclusive. This is because physiologic cortisol varies widely throughout the day, making the test inherently unreliable. Furthermore, suppressed adrenal glands can nonetheless produce a baseline cortisol level that falls in the normal range, even though the adrenals are not communicating with the pituitary and therefor not responding to ACTH. Therefore, the stimulation test is preferred.

There's no role for simply checking serum cortisol in patients on steroids.


UpToDate Approach

Step 1- Assess their risk of adrenal suppression.

If high risk (taking 10-20mg pred daily for three weeks or more), then you simply assume they are suppressed and treat them accordingly. Basically, the treatment is gradual, careful weaning of steroids.

If low risk (getting steroids for less than 3 weeks), assume not suppressed.

If someone is moderate risk or you're unsure, THEN assessment of adrenal axis is warranted. Go on to step 2:

Step 2- Assessing adrenal suppression

Ideally, start with a low dose ACTH stimulation, 1 mcg cosyntropin (which is synthetic ACTH). Measure serum cortisol immediately before the dose and 30 minutes after. This test is more sensitive because it uses physiologic levels of hormone, and it's faster because it can be completed in 30 minutes (as opposed to an hour with the high dose test).

If the serum cortisol is >17 mcg/dL, they don't have suppression. If greater than 25, their adrenal axis is intact. See below for between 18-25.

The trouble with the low dose version is that you need an IV (which is not usually a problem in the hospital). The other difficulty is that the cosyntropin dose needs to be mixed--the vial contains 250mcg, and must be appropriately diluted. If pharmacy or nursing can do this reliably, you're in good shape.

If low dose is not feasible, use the high dose test. This involves 250mg cosyntropin (entire vial) and measuring cortisol immediately before, 30 min, and 60 min after. This high dose is intended to be able to use IM or IV. The serum cortisol cutoff is the same >17.

Alternatives are the 8 hour and 48 hour stimulation tests. These are rarely used. The 48 hr test may be useful to distinguish secondary from tertiary adrenal suppression.


COMPLICATORS:
- If cortisol is 18-25 after stimulation, it is unclear what to do. I would repeat the test.

- Cortisol testing in the ICU is difficult to interpret and controversial, with no clear guidance on how to assess.

- Birth control can falsely elevate serum cortisol levels (because estrogen increases cortisol binding globulin).