The mechanism for a blunted thyroid stimulating hormone (TSH) response to thyrotropin releasing hormone (TRH) in alcoholics is not known. We performed a combined TRH and gonadoliberin stimulation test on three well-defined groups of nondepressed alcoholic men. Group A comprised patients with acute withdrawal symptoms (n = 28), group B patients abstinent for 5-8 weeks (n = 29) and group C patients who had been abstinent for > 2 years (n = 16). Twenty-two healthy male volunteers were used for comparison. A blunted TSH response to TRH (delta TSH < 5 microU/l) occurred only in groups A (39%) and B (17%). In group A delta TSH showed a significant negative correlation with the severity of withdrawal symptoms and a significant positive correlation with serum magnesium levels. In group B, patients with a family history of alcoholism had significantly lower delta TSH levels than those without such a family history. Groups did not differ with respect to basal and delta prolactin, and TSH responses were not significantly associated with vitamin deficiency, cortisol levels or free thyroid hormone levels. We conclude that TRH stimulation test blunting appears to be related to factors operating in the withdrawal state and improves with continued abstinence. A possible role of genetic factors and serum magnesium needs to be further explored.