Evidence of Subcutaneous Tissue Lipolysis Enhancement by Endogenous Cortisol in Critically Ill Patients Without Shock

BACKGROUND/AIM: Cortisol is involved in in many aspects of adipose tissue metabolism. A positive association between plasma cortisol and lipolysis has been observed. Critically ill patients exhibit 'lipemia of sepsis'. The aim of the present study was to study, in septic ICU patients, adipose tissue lipolysis in relation to tissue cortisol using microdialysis (MD). PATIENTS AND METHODS: We studied 17 mechanically-ventilated patients (9 men; mean±SD age=63±19 years) with a diagnosis of severe sepsis. Upon ICU admission, an MD catheter was inserted under sterile conditions into the subcutaneous adipose tissue of the upper thigh. On days 2, 3 and 4, MD samples were collected six times per day for glycerol (used as an index of lipolysis) and tissue cortisol determinations. The mean of these six collections was used for analysis (normal values for adipose tissue glycerol <200 μmol/l). Statistics were carried-out with analysis of covariance (ANCOVA) and linear regression. RESULTS: More than half of the samplings (19/31) indicated accentuated lipolysis with above-normal MD glycerol levels. By ANCOVA, MD glycerol (log values) was associated with MD cortisol (log values) (p=0.012) and was not associated with age or day of sampling. Furthermore, MD glycerol (log values) was positively correlated to MD cortisol (log values) (r=0.490, p=0.012). DISCUSSION: Changes in interstitial/tissue cortisol may not be reflected in (total) plasma cortisol concentration. Thus, it is interesting that we observed, albeit weak, an association between tissue lipolysis (via MD glycerol levels) and MD cortisol, verifying (although modestly so) the well-known association between lipolysis and cortisol.