Hypothyroidism in the elderly.

This review describes the changes in thyroid physiology with aging and notes that normal thyroid status is maintained with advanced age. The increased frequency of hypothyroidism in the elderly is stressed with consideration given to the multiple possible etiologies. The natural history of hypothyroidism is considered as evidenced by the various hormonal abnormalities in subjects with autoimmune thyroiditis and patients previously treated with radioiodine. The potential significance of subclinical hypothyroidism is discussed in regard to nonspecific symptoms and subtle cardiovascular manifestations. The problems in the clinical and laboratory diagnosis of hypothyroidism are reviewed with emphasis on the high index of suspicion and cautious interpretation of plasma thyroxine and thyroid-stimulating hormone (TSH) levels required. Finally the potential problems in treating hypothyroidism in the elderly are discussed in regard to dosage requirements and the need to avoid subclinical hypothyroidism by using the ultrasensitive TSH assay.