Some conditions that cause high levels of TSH in the body are Hashimoto's disease, thyroid nodules and hypothyroidism, states Healthline. High levels of TSH, or thyroid-stimulating hormone, are usually accompanied by low levels of T3 and T4, the hormones produced by the thyroid gland. This results in hypothyroidism, which is an underactive thyroid gland.
Hashimoto's disease, an autoimmune disease, is characterized by high levels of TSH, fatigue, weight gain, constipation and dry skin, according Healthline. Although this disease has no cure, it is treated with hormone-replacement therapy and surgery. The latter is only necessary if the enlarged thyroid or goiter needs to be removed.
Thyroid nodules can cause either high or low levels of TSH, says Healthline. These nodules, or growths, appear on the thyroid gland and can be filled with fluid or be cancerous. Often, these growths are asymptomatic. However, depending on the cause, they can be accompanied by dry skin, cold intolerance, weight gain, nervousness and increased appetite. If the nodules are benign, they require no treatment. If they're cancerous, the entire thyroid gland might need to be removed.
Hypothyroidism, causing high TSH levels, is caused by an underactive thyroid gland that results in hoarseness, muscle weakness, weight gain, a puffy face and thinning hair, explains Mayo Clinic. It can also cause impaired memory, depression and a slowed heart rate. Hypothyroidism can be a symptom of another condition, such as radiation therapy, congenital disease, iodine deficiency or a pituitary disorder.