Background: The regulation of leptin in patients with critical illness is poorly understood. Sex, diet, body mass, and cytokines may all play a role.
Objective: The aims of this study were to determine the factors influencing leptin concentrations in hospitalized patients beginning total parenteral nutrition (TPN) and whether a 3-d regimen of TPN would further increase plasma leptin concentrations above baseline.
Design: Twenty-six patients requiring TPN were enrolled in this prospective, nonintervention study. Only 20 (11 women and 9 men) completed all 3 d of TPN.
Results: Baseline plasma leptin in the TPN patients ranged from 62.5 to 1625 pmol/L ( +/- SD: 419 +/- 387; n = 26) and was not significantly different between men (444 +/- 494 pmol/L) and women (363 +/- 244 pmol/L). Baseline plasma insulin ranged from 76 to 695 pmol/L (271 +/- 188; n = 26) and was not correlated with plasma leptin. Leptin concentrations increased after 3 d of TPN, from 356 +/- 300 to 794 +/- 600 pmol/L (P < 0.05) in parallel with an increase in insulin from 257 +/- 187 to 979 +/- 917 pmol/L (P < 0.01) in the 20 patients who completed the study; however, the changes were not correlated when expressed as percentages. Although the men and women had insulin responses to feeding that were not significantly different, leptin concentrations did not increase significantly in men but increased 3-fold in women (to 1094 +/- 638 pmol/L; P < 0.01).
Conclusions: Leptin regulation in patients with a critical illness differs substantially from that in healthy persons. The importance of glucose and insulin in leptin secretion remains unclear, especially in men.