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Endemic Goiter in Vietnam^*

JEROME M. HERSHMAN, DANG TRAN DUE, BURT SHARP, LE MY, JOHN R. KENT, LE NGOC BINH, ALLAN W. REED, LAM DINH PHUC, ANDRE J. VAN HERLE, NGUYEN ANH THAI, TRAN XUAN TROUNG, NGUYEN VAN VAN, MASAHIRO SUGAWARA and A. EUGENE PEKARY

Endocrine Research Laboratory, Medical and Research Services, Wadsworth Veterans Administration Medical Center, UCLA School of Medicine Los Angeles, California 90073
Endocrinology Hospital Hanoi, Vietnam

Address requests for reprints to: Jerome M. Hershman, M.D., Endocrinology-111D, Wadsworth Veterans Administration Medical Center, Los Angeles, California 90073.

Endemic goiter involves about 15% of the population of Vietnam. To define the role of various factors which contribute to endemic goiter in Vietnam, we surveyed 935 people in Vancon, a lowland commune with goiter appearing only in the past decade, and 619 people in Dich Giao, a highland commune with endemic goiter treated erratically with iodized salt. In Dich Giao, cassava, a goitrogenic food, constitutes half of the dietary caloric intake. The prevalence of goiter was 45% in Vancon and 28% in Dich Giao. Laboratory studies were carried out in a subgroup of 63 subjects in Vancon, 52 subjects in Dich Giao, and a control group of 46 women in Hanoi.

The mean serum TSH levels were 1.4 ± 0.1 (±SE) µU/ml in Hanoi, 3.6 ± 0.5 µU/ml in Vancon (P < 0.001), and 2.4 ± 0.2 µU/ml in Dich Giao (P < 0.05). The mean serum T₄ concentrations were similar in the three groups, but the mean free T₄ concentration was low in Vancon. Serum T₃ levels and the T₃ to T₄ ratios were significantly elevated in the goitrous regions. The mean serum thyroglobulin (Tg) concentrations were 27 ± 3 ng/ml in Hanoi, 101 ± 20 ng/ml in Vancon (P < 0.01), and 44 ± 5 ng/ml in Dich Giao (P < 0.01). The 4-h thyroid uptake was higher in Vancon than in Hanoi. The urinary iodine concentration was low in both goitrous regions, and urinary thiocyanate was increased in Dich Giao, reflecting the ingestion of cassava.

For all regions combined, there was a direct correlation between serum TSH and T₃ and between serum TSH and Tg. In Vancon, where iodine deficiency was more severe, there was an inverse correlation between thyroid uptake and the urinary iodine concentration; thyroid uptake correlated directly with serum T₃, the T₃ to T₄ ratio, and serum Tg. In Dich Giao, there was no correlation between urinary thiocyanate and thyroid uptake or urinary iodine levels.

The data show that low iodine intake is a major factor in the causation of goiter in Vancon, where iodine deficiency had not been suspected. The ingestion of cassava in Dich Giao did not cause a major change in thyroid hormone economy even though iodine intake was marginally low; the data suggest that the goitrogenic effect of cassava is easily overcome by supplementary iodine, even when it is ingested irregularly.

^* This work was supported by the Reynolds Foundation, U.S. Committee for Scientific Cooperation with Vietnam, and V.A. Medical Research Funds.

Nuclear Medicine Section, Bach Mai Hospital.

Anti-Goiter Station, Hoa Binh Province.

Received August 13, 1982.

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