Increased insulin binding to erythrocytes in anorexia nervosa: restoration to normal with refeeding

We studied [125I] insulin binding to circulating cells in patients with anorexia nervosa (eight females), in the basal cachectic state (seven patients) and after weight gain (eight patients) and compared the values to those obtained in 17 normal volunteers (eight females and nine males). Untreated patients showed increased insulin binding to receptors on erythrocytes (mean +/- S.E.M., 12.2 +/- 0.99 per cent of total); after weight gain, these increased levels returned to normal (6.8 +/- 0.42 vs 6.7 +/- 0.63 per cent of total). Increased binding was due to an increased number of receptors per cell, with little or no change in receptor affinity. In five patients (one untreated, four treated), results of [125I] insulin binding to erythrocytes correlated closely (r = 0.982) with results obtained with monocytes. We conclude that in patients with anorexia nervosa, insulin binding to receptors is altered and that the abnormality is corrected by restoration of normal food intake and body weight.