Hypothyroidism - Complications

Cholesterol and Lipid Levels. Hypothyroidism is significantly associated with high levels of total cholesterol, LDL (the so-called bad cholesterol), triglycerides, and other lipids (fat molecules) associated with heart disease. Treating the thyroid condition with thyroid replacement therapy can significantly reduce these levels. (Some experts are suggesting, in fact, that patients with high cholesterol should be assessed for thyroid function before they are given cholesterol-lowering agents, although this is controversial.) Even subclinical hypothyroidism poses a higher risk for unhealthy cholesterol levels. Research is mixed, however, on whether this association has any significance and justifies treating this mild condition.

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High Blood Pressure (Hypertension). Hypothyroidism may slow the heart rate to less than 60 beats per minute, reduce the heart's pumping capacity, and increase the stiffness of blood vessel walls. All of these effects may lead to high blood pressure. Indeed, patients with hypothyroidism have a three-fold increased risk of hypertension. Blood flow may even be affected in patients with subclinical hypothyroidism. All patients with chronic hypothyroidism, especially pregnant women, should have their blood pressures checked regularly.

Homocysteine. Studies are finding that hypothyroidism is associated with elevated levels of homocysteine, an amino acid that is a suspect in heart disease. High levels can be prevented with supplements of vitamins B6, B12, and folic acid.

Effects of Hypothyroidism and Subclinical Hypothyroidism on the Mind

Depression. Depression is common in hypothyroidism and can be severe. Some psychiatrists suspect that even subclinical hypothyroidism may contribute to depression. The two disorders may have some common physiological basis. In one study, both triiodothyronine (T3) and L-tryptophan (a chemical important in depression) appeared to be taken up by the same portion of red blood cells. Interesting implications of the study are that alterations in one substance may affect the other. Adding thyroid hormones to antidepressants, in fact, hastens a depressed patient's recovery, even in some patients who have not been diagnosed with hypothyroidism. Hypothyroidism should be considered as a possible cause of any chronic depression, particularly in older women.

Mental and Behavioral Impairment. Untreated hypothyroidism can, over time, cause mental and behavioral impairment and eventually, even dementia. Whether treatment can completely reverse problems in memory and concentration is uncertain, although many experts believe that only mental impairment in hypothyroidism that occurs at birth is permanent.