How Does Hyperthyroidism Cause Hair Loss?

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If you have hyperthyroidism your thyroid gland is overactive, meaning it produces too much of the hormone thyroxine. This condition can significantly accelerate your body's metabolism and may cause sweating, sudden weight loss, restlessness and a rapid or irregular heartbeat, according to the Hyperthyroidism also can cause hair loss.


Hypethyroidism can trigger a condition called telogen effluvium that results in hair loss, according to Warren Heymann, author of “Thyroid Disorders with Cutaneous Manifestations.” Hypothyroidism, a condition in which your body does not produce enough thyroid hormone, also can cause this condition. Elevated thyroid hormone levels also can cause your hair to gray. This is common in Graves Disease in which the thyroid is overstimulated.


Telogen effluvium affects your hair loss and growth cycle, Heymann notes. Regular hair growth has three phases -- the growth phase called anagen, the transitional phase called catagen and the dormant phase called telogen. Normally, about five to 15 percent of your scalp’s hair follicles are in the telogen phase at a time. However, telogen effluvium disrupts the timing of this cycle causing an abnormal percentage of hairs to shift to the telogen phase.

Time Frame

You’ll notice hair loss several weeks or months after your hyperthyroidism disrupts your hair growth cycle. Your most obvious hair loss will be on your scalp, according to the American Osteopathic College of Dermatology. You are most likely to notice the shedding when shampooing, brushing or even gently manipulating your hair. You may even notice clumps of hair on your pillow, says Ridha Arem, author of “The Thyroid Solution.” AOCD advises that you also may have hair loss in other places on your body.


If you suffer telogen effluvium due to an overactive thyroid, the hairs that you shed are likely to have club-shaped roots. These roots are easily identified under a microscope, according to AOCD. You will need to visit a doctor to determine if you are suffering from hyperthyroidism. Your doctor will take a medical history and order a blood test to measure the levels of thyroid hormone in your body. Your doctor also may order a radioactive iodine uptake test or a thyroid scan, according to the National Institute of Diabetes and Digestive and Kidney Diseases, or NIDDK.


Treating your hypothyroidism will halt telogen effluvium hair loss, according to AOCD. Your shedding is likely to decrease slowly over six to eight months once your hyperthyroidism is addressed. It may take your body up to a year to replace the weak hair that resulted from your imbalance, however, notes Arem. If you have hyperthyroidism, you need to decide on a treatment option with your doctor. Several treatments are possible, and your doctor needs to take into account how severe your disorder is, your age and your physical condition. Options include surgery, anti-thyroid medications and radioactive iodine, according to the NIDDK. Supplementing with vitamins and minerals such as calcium, or additional calories also may be appropriate, but should be done under your doctor’s supervision.