PLASMA LEPTIN, ENERGY-INTAKE AND HUNGER FOLLOWING TOTAL HIP-REPLACEMENT SURGERY

1. This study aimed to investigate the possible role of leptin in post -traumatic anorexia by making pre- and post-operative (0-8 days) measu rements of circulating leptin concentrations in six patients undergoin g elective total hip replacement for osteoarthritis. 2. Mean daily hun ger rating (four categories) and food intake (assessed by food record charts) were measured pre-operatively, as well as post-operatively for the first 5 days (days 0-5). Leptin concentrations, circulating metab olites [glucose, non-esterified fatty acids, glutamine and 3-hydroxy-b utyrate] and insulin and cortisol concentrations were measured pre-ope ratively (day 0) and postoperatively (days 1, 2, 3, 5 and 8). 3. Mean leptin concentrations were significantly increased only on day 1 (56% increase compared with pre-operative values, P<0.009), whereas food in take (only 0.6 MJ on day 0) and hunger (5/6 patients 'not hungry' on d ay 0) only gradually improved over the next few days, (The energy inta ke over the first 5 days was 56% of the pre-operative value.) 4. Circu lating insulin and cortisol concentrations were elevated on day 1 comp ared with pre-operative values on day 0 (P < 0.05). Of the measured me tabolites implicated in the control of food intake, circulating non-es terified fatty acids and 3-hydroxybutyrate were not significantly alte red in the post-operative period, but significant hyperglycaemia was n oted on day 1 compared with day 0 pre-operatively (8.8 compared with 6 .4 mmol/l glucose; P < 0.01). 5. It is concluded that circulating lept in is involved in the early (< 24 h) acute-phase response after modera tely severe surgical trauma (characterized biochemically by a substant ial acute-phase protein response, hypoalbuminaemia, hyperglycaemia and hypoglutaminaemia), Therefore, leptin may be implicated in post-traum atic anorexia, although other factors are likely to be involved, espec ially after the first 24 h when circulating leptin concentrations are no longer elevated.