Subclinical hypothyroidism refers to a state in which patients do not exhibit the symptoms of hypothyroidism. These patients also have a normal amount of circulating thyroid hormone. The only abnormality is an increased TSH on their blood work. This implies that the pituitary gland is working extra hard to maintain a normal circulating thyroid hormone level and that the thyroid gland requires extra stimulation by the pituitary to produce adequate hormones. The majority of these patients can be expected to progress to obvious hypothyroidism, especially if the TSH is above a certain level. While there is some controversy, many endocrinologists will treat such patients, especially if they have a high cholesterol blood level. The abnormal cholesterol profile will likely show improvement with thyroid hormone replacement. If the cholesterol levels are normal, and the patient feels well, it is also reasonable to follow these patients without treatment and repeat the blood TSH and thyroid hormone levels in 4 to 6 months to see if more significant hypothyroidism is apparent. Both of these approaches are reasonable and patients should be encouraged to speak with their physicians about specific concerns and preferences.