Preliminary Studies on Thyroid Function in Welders

Twenty healthy male welders with an average age of 38.4 ± 8.67 yr (mean ± SD), having average occupational exposure of 13.5 ± 5.2 yr (mean ± SD), and performing manual electric arc and/or gas welding participated in the study. Job operation mainly included welding and cutting of iron objects. Simultaneously, an equal number of control subjects, matched with age, sex, socio-economic status and having no previous occupational exposure to welding profession or other chemicals were also studied. All subjects were interviewed for their life-style, and their occupational history was recorded. Intravenous blood samples (6-8 ml) from both the groups were drawn in a morning session. Serum was separated by centrifugation and used for hormonal analysis. Serum thyrotropin (thyroid stimulating hormone, TSH) was estimated by solid phase immunoradiometric assay (TSH/IRMA)7). Serum total T3 ( TT3)8 and total T4 (TT4)9) were measured by radio immunoassay (RIA). Assay sensitivity (n=5) as determined by the lowest standard, different from zero (t-test), was 0.58 ng/dl for T3; 0.2 μg/dl for T4; and 0.03 μIU/ml for TSH, respectively. Intra-assay coefficients of variation (CVs) for reference sera (n=5 each) with T4 concentrations of 7.5 and 15 pg/dl were 3.4% and 4.8%, respectively. Similarly for T3 reference sera, (1.3 ng/ml) and TSH reference sera (30 /AU/ml); the values of CVs (n=5 each) were 4.3% and 4.6%, respectively. Statistical analysis was performed using Student's `t' test.