HDL-cholesterol level and cortisol response to synacthen in critically ill patients

To explore the relationship between cholesterol levels and the adrenal cortisol response to synacthen in critically ill patients.

Prospective observational study.

Critically ill patients with multiple organ dysfunction syndrome (MODS) with possible adrenal dysfunction defined as unexplained hypotension, ongoing inotropic support, unexplained fever, unexplained hyponatraemia or a combination of these symptoms.

HDL-cholesterol levels (HDL), total cholesterol levels (TC), and triglycerides (TG) before administration of synacthen. LDL-cholesterol was calculated using the Friedewald formula. Basal cortisol and response to 250 microg synacthen intravenously was measured. A cortisol rise of 0.25 micromol/l in a 30-min or 60-min blood sample after synacthen infusion was defined as a proper adrenal response.

Patients with a proper response to synacthen showed higher HDL-cholesterol levels than patients without that response ( P=0.02). Severity of disease as measured by APACHE II or SOFA was not a confounder. LDL-cholesterol levels were extremely low in both responders and non-responders and were not associated with the absolute rise in cortisol. In linear and logistic regression analysis HDL-cholesterol was the sole predictor of cortisol response.

Adrenal cortisol response to a "classic" 250-microg synacthen test relates in critically ill patients to HDL-cholesterol levels. LDL and TC levels did not show such a relation. These findings are in concordance with known biochemical pathways of cortisol production.