Tissue Lipolysis Vs Tissue Cortisol in Septic and Non-Septic Critical Illness

Introduction: Cortisol (F) is enmeshed in adipose tissue metabolism in many aspects (1). A positive association between plasma F and lipolysis has been observed. Critically ill patients show the “lipemia of sepsis”.

Aim: To study, in septic and non-septic ICU patients, adipose tissue lipolysis vs tissue F, using microdialysis (MD).

Subjects and methods: We studied 43 (24 men & 19 women, mean age±SD: 63±19 years) mechanically ventilated patients with a diagnosis of septic shock (n=21) or systemic inflammatory response syndrome/severe sepsis (n=22). Upon ICU admission a MD catheter was inserted under sterile conditions into the subcutaneous adipose tissue of the upper thigh. Excluding patients on steroid therapy, on day 2 (n=27), day 3 (n=24) and day 4 (n=21) MD samples were collected six times per day for MD glycerol (MD GLYC; used as an index of lipolysis) and tissue F. The mean of these 6 collections was used for analysis (normal values for adipose tissue GLYC glycerol < 200 μmol/L). Statistics were done with analysis of covariance (ANCOVA) and linear regression.

Results: Most samplings (44/72) indicated accentuated lipolysis with above-normal MD GLYC levels. MD GLYC was associated with MD F (ANCOVA p=0.022) and was not associated with age, day of sampling or presence of shock. MD GLYC was weakly correlated to MD F (r=+0.242, p=0.045).

Discussion: Changes in interstitial/tissue F may not be reflected in plasma (total) F concentration (2). Thus it is interesting that we observed an - albeit weak - association between tissue lipolysis (via MD GLYC levels) and MD F, verifying (though modestly so) the well-known association between lipolysis and F (3).