Critical Illness-related Corticosteroid Insufficiency - Diagnosis

Diagnosis

The exact diagnostic tests and cut-off values to diagnose critical illness-related corticosteroid insufficiency are not agreed upon. This also applies to the distinction between absolute and relative adrenal insufficiency, a reason why the term critical illness–related corticosteroid insufficiency is preferred to relative adrenal insufficiency. The variation in cortisol levels according to disease type and severity, as well as variation within the same patient, hampers the establishment of a clear threshold below which CIRCI occurs. Moreover, in patients whose adrenals are already maximally stimulated, a stimulation test would not be informative. Furthermore, a short test might not adequately assess response to the chronic stress of critical illness.

Both random total cortisol levels, total cortisol levels or increment after ACTH stimulation tests, free cortisol levels, or a combination of these have been proposed as diagnostic tests. Other stimulation tests for adrenal insufficiency which are used in non-critical patients, such as the test using metyrapone or a test which employs insulin to induce hypoglycemia, are not preferred for CIRCI. Both a metyrapone-induced decrease in cortisol and hypoglycemia are potentially harmful to intensive care patients. The exact dose of ACTH remains a matter of debate. In the CORTICUS study, ACTH stimulation testing predicted mortality whereas baseline cortisol levels did not. However, possible benefits of corticosteroid therapy do not seem to be completely predicted by ACTH stimulation testing. For these reasons, guidelines currently do not recommend that ACTH stimulation testing should guide the decision whether or not to administer corticosteroids. Cortisol immunoassays on the other hand have been shown to be prone to both over- and underestimation.