1. Plasma catecholamine, blood pressure and heart rate responses to standing were measured in ten alcoholics during withdrawal, ten alcoholics after 2–7 weeks of abstinence from alcohol, six abstinent alcoholics with orthostatic hypotension and ten normal control subjects.
2. Withdrawing alcoholics had supine and standing heart rates and plasma noradrenaline and adrenaline concentrations that were higher than in abstinent alcoholics or control subjects. Supine blood pressures were also higher in withdrawing alcoholics than in abstinent alcoholics or control subjects, but on standing blood pressures in withdrawing alcoholics fell, four patients having a fall of more than 30/5 mmHg.
3. Abstinent alcoholics without orthostatic hypotension had higher basal and standing concentrations of noradrenaline than control subjects but normal heart rates and adrenaline concentrations.
4. Abstinent alcoholics with orthostatic hypotension showed a wide range of basal plasma noradrenaline concentrations and were found to have variable plasma noradrenaline responses to standing, three subjects having normal responses and three subjects having no or little increase in plasma noradrenaline on standing.
5. It is concluded that alcohol withdrawal is associated with increased sympathetic nervous activity, as reflected by raised supine and standing plasma concentrations of catecholamines, and that even after 2–7 weeks of abstinence from alcohol plasma noradrenaline concentrations may be higher than in control subjects. Despite increased sympathetic nervous responses to standing, alcoholics during withdrawal have impaired blood pressure control and some may exhibit orthostatic hypotension. Orthostatic hypotension may also be observed in alcoholics during continuing abstinence from alcohol; in some of these patients failure of reflex noradrenaline release in response to standing may contribute to orthostatic hypotension.