What Is a High TSH?

Thyroid stimulating hormone (TSH) is produced by the pituitary gland. Its job is to maintain normal levels of thyroid hormones in the blood, which in turn control your body's use of energy. TSH levels in the blood determine whether your thyroid is normal, underactive or overactive. High TSH levels indicate low levels of thyroid hormones and an underactive thyroid.

Identification

• A blood test is used to measure levels of circulating TSH. A TSH result above the normal range of 9 to 30 ulU/ml at 20-30 minutes is high. Additional blood testing for thyroid hormones is necessary to determine why TSH levels are high.

Significance

• When TSH levels are high, it is an indicator to your physician that something is wrong with your thyroid gland. It means that the thyroid gland is ignoring messages from the pituitary gland to produce its own hormones.

Cause

• The most common cause of high TSH is hypothyroidism, often due to an inflammatory autoimmune disorder called Hashimoto's Thyroiditis. A less common cause in modern times is iodine deficiency.

Effects

• When TSH levels are high and production of thyroid hormones is low, common symptoms include fatigue, weakness, weight gain, constipation, cold sensitivity, forgetfulness and dry skin.

Treatment

• Thyroid hormone replacement therapy, prescribed in appropriate doses, will normalize both thyroid hormone and TSH levels in the blood and help alleviate symptoms.