Random Serum Cortisol Levels are misleading

Adrenal insufficiency in critically ill patients is frequently misdiagnosed due to an over-reliance on total serum cortisol levels, which fail to account for the physiological impact of protein binding. Cortisol exists primarily in protein-bound forms, with only 10% circulating as biologically active free cortisol. Conditions common in the ICU, such as sepsis, trauma, and major surgery, significantly reduce concentrations of albumin and corticosteroid-binding globulin, leading to artificially low total cortisol readings. Relying on these misleading values often results in the unnecessary administration of steroids, which exacerbate risks like poor wound healing, infections, and deep venous thrombosis. Clinicians should prioritize understanding the patient's protein status and the limitations of current assays rather than reflexively treating based on total cortisol measurements, as nearly 40% of patients may be misdiagnosed as adrenal insufficient.