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Thyroid disease in hemochromatosis. Increased incidence in homozygous men
Insights
Hemochromatosis patients show higher thyroid dysfunction, particularly men. Iron accumulation in the thyroid may lead to hypothyroidism and antithyroid antibodies.
Area of Science:
- Endocrinology
- Genetics
- Pathology
Background:
- Hereditary hemochromatosis is an iron overload disorder.
- Thyroid function in hemochromatosis patients is not well understood.
Observation:
- Thyroid function was assessed in 49 patients homozygous for the hemochromatosis allele.
- Thyroid dysfunction was observed in 3 of 34 men and none of 15 women.
Findings:
- Hypothyroid patients had elevated antithyroid antibodies.
- Thyroid autopsy revealed iron accumulation, fibrosis, and lymphocytic infiltration.
- Men with hemochromatosis exhibited a significantly higher incidence of thyroid disease.
Implications:
- Iron deposition may cause thyroid injury, leading to autoimmune thyroid disease.
- The study suggests a strong link between hemochromatosis and thyroid dysfunction.
- Men with hemochromatosis have a substantially increased risk of thyroid disorders.
Abstract:
The thyroid function of 49 patients homozygous for the hemochromatosis allele was studied by measurement of serum thyroxine and thyrotropin concentrations. Of 34 homozygous men, three were found to be hypothyroid (thyroxine, less than 3.0 micrograms/dL and thyrotropin, greater than 40 ImU/mL) and one was hyperthyroid (thyroxine, 24 micrograms/dL). All 15 homozygous women had normal thyroid function. The hypothyroid patients had elevated titers of antithyroid antibodies. Histologic examination of the thyroid at autopsy of one hypothyroid patient showed notable iron accumulation and fibrosis with modest lymphocytic infiltration. The causative importance of iron deposition in thyroid diseases associated with hemochromatosis was suggested by the reversal of the usual sex ratio of thyroid dysfunction. Men with hemochromatosis had a much greater iron load than women, and they also had a surprisingly higher incidence of thyroid disease. Iron may have caused injury to the thyroid, followed by the development of antithyroid antibodies and hypothyroidism. The frequency of thyroid disorders in men with hemochromatosis is about 80 times that of men in the general population.