Three Frequently Asked Questions About Hypothyroidism

Hypothyroidism is a common health problem. It is a hormonal disorder where there is low level of thyroid hormones, namely T3 and T4, which are essential for various vital physiological functions of the body. Deficiency of thyroid hormones (T3 and T4) lead to number of clinical problems.

What is subclinical hypothyroidism?

In case of “overt” hypothyroidism there is elevation of TSH (Thyroid Stimulating Hormone) and low blood levels of T3 and T4 because, when TSH is high, T3 and T4 are low. Subclinical hypothyroidism is milder form of the disease, where there is normal T3 and T4, especially free forms of T3 and T4 but TSH is high. The clinical presentation of subclinical hypothyroidism are variable. In many patients with subclinical hypothyroidism, there may not be any symptom, whereas some may have minor symptoms, without classical symptoms of hypothyroidism such as cold extremities, feeling of cold even during summer, weakness, fatigue etc. Some percentage (2.5% to 4.3%) of patients with subclinical hypothyroidism, converts to overt hypothyroidism every year. In some patients of subclinical hypothyroidism, antibodies against thyroid peroxidase can be detected and those have higher risk of developing overt hypothyroidism.

Should subclinical hypothyroidism be treated?

There is no consensus among doctors, regarding treatment of subclinical hypothyroidism. Some doctors advocate treatment, while some doctors advise against treatment, because there is risk of overtreatment and risk of hyperthyroidism. In one study it was seen that there is modest increase in risk of coronary heart disease (CHD) among untreated cases of subclinical hypothyroidism. Currently most doctors agree that if TSH level is high but below 10 mIU/L need no treatment with thyroid hormone without any symptoms and treat them if there are some symptoms of hypothyroidism or there is detectable antibodies against thyroid peroxidase or if there is history of heart disease or patient is at increased risk of heart disease from other causes.

Hypothyroidism and pregnancy

During pregnancy, TSH level between 2.5 to 10 mIU/L is considered normal and more than 10 mIU/L is considered as hypothyroidism, even in presence of normal thyroid hormone level. During pregnancy, free thyroid hormones (T3 and T4) may be abnormal (usually lower than usual), due to increased binding of thyroid hormones to thyroid binding globulin and decreased binding to albumin. Hence, for diagnosis of hyperthyroidism during pregnancy, total thyroid hormones (T3 and T4) should checked instead of free form, which is commonly used for diagnosis of hyperthyroidism. If there is abnormality in thyroid hormone levels or TSH level, they should be corrected according to the stage (trimester) of pregnancy.

 

Related Posts

Leave a Comment

Loading...