Serum thyroglobulin in inhabitants of an endemic goiter region of New Guinea.

Serum thyroglobulin Tg(RIA) was studied in 161 residents of the Nomane region of New Guinea. The incidence of antithyroglobulin antibodies (ATA) and antimicrosomal antibodies (anti-M) was also studied to assess the role of autoimmunity in goitrogenesis. ATA were detected in only 4 sera; these sera were excluded from the study since ATA interfere in the Tg radioimmunoassay. Anti-M antibodies were undetectable in all of 105 subjects whose sera were analyzed. Mean (+/-se) serum Tg(RIA) in the 84 nongoitrous (NG) subjects was 163.1 +/- 17.2 ng/ml, whereas that in 77 goitrous (G) subjects was 208.1 +/- 19.8 ng/ml; both values were much higher (P is less than 0.001) than that (5.1 +/- 0.49 ng/ml) in normal Californian subjects. The mean serum thyroid stimulating hormone (TSH) in the NG group (12.1 +/- 2.1 muU/ml) was not statistically different from that in the G group (10.1 +/- 1.5 muU/ml). Serum Tg(RIA) correlated positively with log TSH (r equals 0.38 P is less than 0.001). Intrigued by the finding of goiters in some residents of an endemic goiter region and its absence in other residents exposed to the same environmental factors, we evaluated the possibility that the thyroid glands of subjects who develop goiters may be inherently more responsive to any given level of TSH than those of the inhabitants without goiters. However, the slope of the correlation between serum Tg(RIA) and log TSH was only slightly (0.1 is less than P is greater than .05) higher in G than in the NG group. These studies suggested that factors other than thyroidal responsiveness to TSH must also be important in goiterogenesis of endemic goiter regions. We conclude that 1) serum thyroglobulin is a sensitive parameter of chronic as well as acute thyroidal stimulation; 2) Thyroid autoimmunity and increased thyroidal response to TSH do not explain goiterogenesis in New Guinea and attention should be focused on other possibilities.