The thyroid gland is an organ that produces hormones that regulate important bodily functions, including metabolism. The thyroid is stimulated to produce its hormones by another hormone called thyroid stimulating hormone, or TSH. When thyroid hormone levels are abnormally high, TSH is typically low. Low TSH can cause a host of symptoms, ranging from general symptoms to symptoms specific to a particular organ.
Fatigue, nervousness, restlessness and weakness are common symptoms of low TSH. Because these symptoms can be felt with a variety of other conditions, they may not be attributed to low TSH initially. Muscle cramps may also occur but be attributed to another cause. People with low TSH may be very sensitive to the heat and unable to tolerate it. A warm summer day for most people may be unbearably hot for them. People with low TSH may also sweat more than others.
Heart and Lungs
People with low TSH commonly feel their heart pounding hard. Extra heartbeats and a racing heart may also occur. An abnormal heart rhythm called atrial fibrillation may occur when TSH is low. Sometimes the hormone abnormalities related to low TSH have such a negative effect on the heart, it leads to the development of a heart muscle disorder called cardiomyopathy. Heart failure can occur with this condition. Becoming easily winded with normal activities is another common manifestation of low TSH.
The skin may be unusually warm and may even have a reddish hue from the increased blood flow that can occur with a low TSH. Skin may become darker or smoother than usual. Hair thinning may be noted. Hives and itching may also occur. The skin of the shins may be affected, appearing raised or darker than usual, and it may resemble the peel of a shrunken orange.
Most people with low TSH have an increased appetite. But they can still lose weight despite eating more than usual because their metabolism is revved up. Unlike most younger adults, senior citizens with low TSH may have a decreased appetite rather than an increased appetite. Some people with low TSH have an enlarged thyroid gland, called a goiter. If the goiter is big enough, it can cause difficulty swallowing. Having more frequent bowel movements is fairly common, but people with low TSH rarely experience abdominal pain and vomiting.
Personality and Thinking
Some people with a low TSH experience personality changes that run the gamut from depression to losing touch with reality. Confusion, difficulty concentrating and memory problems, including amnesia, may occur. Other potential symptoms include insomnia, anxiety and irritability.
Call the Doctor
If you experience any symptoms of low TSH, see your doctor, especially if the symptoms last for several weeks or get progressively worse. Blood tests can be done to measure your TSH and thyroid hormone levels.
- UpToDate: Overview of the Clinical Manifestations of Hyperthyroidism in Adults
- New England Journal of Medicine: Graves' Disease
- Current Medical Diagnosis & Treatment 2014; Maxine A. Papadakis, M.D., et al.