High TSH levels can be a symptom of several diseases, including hypothyroidism and, more uncommonly, pituitary tumors, according to WebMD. Long-term untreated hypothyroidism can cause heart disease, obesity, goiter, pain and infertility, as stated by Mayo Clinic.
High levels of thyroid-stimulating hormone do not cause harm on their own; however, these levels indicate that the body is not properly regulating the production of hormones T3 and T4 by the thyroid, as reported by WebMD. In a healthy person, the thyroid produces these hormones in response to stimulation by TSH. These hormones then play a critical role in many body systems, including brain development.
The most common cause of high levels of TSH is hypothyroidism, or diminished activity of the thyroid, according to Mayo Clinic. The body responds to lower levels of T3 and T4 by producing more TSH to compensate for the lowered thyroid activity. This results in increased levels of this hormone that are measurable a simple blood test, as stated by WebMD.
Symptoms of hypothyroidism can include fatigue, cold sensitivity, muscle and joint pain, weight gain, puffiness and depression, the American Thyroid Association explains. Long-term symptoms include obesity and heart disease.
There are many causes of hypothyroidism, including autoimmune disease, medications and pituitary disorders, according to Mayo Clinic. In most individuals, this disease can be managed by taking supplementary thyroid hormone in the form of a pill.