endocrine and metabolic disorders
Hypothyroidism
Subclinical hypothyroidism
Subclinical hypothyroidism is elevated serum TSH in patients with absent or minimal symptoms of hypothyroidism and normal serum levels of free thyroxine (T4). Subclinical thyroid dysfunction is relatively common; it occurs in about 15% of older women and 10% of older men, particularly in those with underlying Hashimoto Thyroiditis . In patients with serum TSH>10 mU/L, there is a high likelihood of progression to overt hypothyroidism with low serum levels of free T4 within the next 10 years. These patients are also more likely to have hypercholesterolemia and atherosclerosis. They should be treated withlevothyroxine, even if they are asymptomatic. For patients with TSH levels between 4.5 and 10 mU/L, a trial oflevothyroxineis reasonable if symptoms of early hypothyroidism (eg, fatigue, depression) are present. Levothyroxinetherapy is also indicated in pregnant women and in women who plan to become pregnant to avoid deleterious effects of hypothyroidism on the pregnancy and fetal development. Patients should have annual measurement of serum TSH and free T4 to assess progress of the condition if untreated or to adjust thelevothyroxinedosage. 