Horm. metabol. Res. 16 (1984) 53-54 ©Georg Thieme Verlag Stuttgart New York Effect of Methadone on TSH and Thyroid Hormone Secretion P.P. Vescovi, G. Gerra, G. Rastelli, G.P. Ceda and G. Valenti Istituto di Clinica Medica Generate e Terapia Medica dell'Università degli Studi di Parma, Parma, Italy Summary The hypothalamus-pituitary-thyroid function was studied in 15 male patients on chronic methadone treatment (40 mg/day). No significant variations of TSH, T 4 , T 3 and rT 3 levels were documented, either in basal conditions or after TRH stimu- lation; however a reduced TSH pituitary response was recorded in some patients (6 out of 15). Key-Words: TSH — Thyroid Hormones — TRH — Opioid System — Methadone — Drug-Addicts Introduction Many aspects of the opioid-induced effects on hypothalamus-pituitary hormonal secretion are well known (De Wied, Van Ree and De Jong 1974; Meites, Bruni, Van Vught and Smith 1979); however con- flicting results on hypothalamus-pituitary-thyroid function have been documented. In chronic heroin addicts there are no significant variations of basal levels of TSH, T 3 and T 4 , but reduced TSH responses to TRH in 50% of the patients have been reported (Brambilla, Nobile, Zanoboni, Zanoboni-Muciaccia and Meroni 1980). During chronic morphine administration a reduction of TSH and thyroid hormone levels has been documented by some (Bruni, Van Vugt, Marshall and Meites 1977), while an increase of T 3 and T 4 levels, with normal fT 3 and fT 4 values, has been described by others (Tolis, Hickey and Guyda 1976). The aim of this study is to evaluate the effects on the hypothalamus- pituitary-thyroid axis of methadone, synthetic analgesic narcotic, which is employed as maintenance therapy for hard drugs. Received: 25 March 1982 Accepted: 25 Sept. 1983 after revision Fig. 1a Behaviour of TSH secretion in methadone addicts compared with range in controls. The shaded areas represent the mean SD of the controls, the symbols ) indicate the addict patients. Fig. 1b Thyroid hormones levels (T 4 , T 3 and rT 3 ) (mean SD): basal values and after TRH stimulation (A) in a group of methadone treated patients ) in comparison to normal controls (o). Materials and Methods 15 male patients were studied (mean age SEM of 28 3.4 years), who had been using different drugs (heroin, morphine) and on maintenance therapy with methadone for at least 4 months (at a dose of 40 mg/day). Weekly examination of the urine excluded the use of other drugs apart from methadone. These was no clinical or laboratory finding for any endocrinological disease. Downloaded by: National University of Singapore. Copyrighted material.