Effects of chronic heroin addiction on pituitary-thyroid function in man

Pituitary-thyroid function has been studied in heroin addicts. Data have been obtained in 10 male addicts, aged 18-24 years, with histories of addiction to heroin alone lasting from 8 months to 4 years, and in 9 controls matched for sex and age. Basal plasma levels of TSH, T4 and T3 were measured. A TRH stimulation test was done, injecting 500 micrograms of TRH iv as a bolus and assaying TSH levels before the injection and at 30 min intervals up to 2 h afterwards. The results revealed no difference between addicts and controls in basal levels of TSH, T4 and T3. The TRH stimulation test induced a blunted TSH rise in 50% of the cases. The possible mechanism of action of heroin on pituitary-thyroid axis is discussed.