1. Hand blood flows in healthy young men and women and in patients with anorexia nervosa were measured in a warm environment by using venous occlusion plethysmography. The mean core temperature of each of the three groups was similar, but the male control subjects and the anorexic patients had significantly higher peripheral blood flows than the female control subjects.
2. Blood flows were determined in the hand after 6 min localized cooling of it at varying temperatures. The female control subjects and the majority of the anorexic patients had blood flows which were similar for a given temperature, and lay between the higher values of the male control subjects and the low values of the remaining anorexic patients.
3. Those patients whose vascular responses to cold were exaggerated were characterized clinically by severe and persistent signs of ischaemia of the extremities during subsequent rehabilitation, unlike the majority of patients whose peripheral circulation rapidly improved.
4. Cold thermal stimuli evoked marked falls in blood flow of the contralateral (non-cooled) hand in the male and female control subjects, but these responses were attenuated or absent in the anorexic patients. An altered set-point for vasomotor thermoregulation in anorexia nervosa could explain these findings.
5. Plasma and whole-blood viscosity and erythrocyte deformability measured in a sample of the patients studied were similar to the values obtained from a sample of the control subjects.
6. It was concluded that the cutaneous vasoconstrictor responses to cold in the majority of the anorexic patients studied were quantitatively normal. The mechanism of the response, however, was different in that the vessels themselves were unusually reactive to cold. Increased cuteneous vasoreactivity to cold could contribute to the severe peripheral hypoperfusion observed in some anorexic patients.