American Medical Association Family Medical Guide - American Medical Association [618]
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Diagnosis
A diagnosis of hypothyroidism is based on the symptoms and a physical examination. The doctor will recommend blood tests to measure blood levels of thyrotropin and antithyroid antibodies (infection-fighting proteins that would indicate an autoimmune response). If a blood test shows a high level of thyrotropin, a diagnosis of hypothyroidism is confirmed. If the blood also contains antithyroid antibodies, the diagnosis is Hashimoto’s disease.
Treatment
If you have hypothyroidism, your doctor will prescribe oral thyroid hormones, which you will need to take for the rest of your life. After a few days of treatment, your symptoms will improve; after a few months, you should recover completely. Myxedema is also treated with thyroid hormones.
Thyroid Nodules
A thyroid nodule is a small lump in the thyroid gland. Some thyroid nodules are cancerous, but most are harmless, noncancerous cysts filled with fluid or functioning thyroid tissue. The cause of thyroid nodules is not known, but doctors think they may result from mutations in genes that control tissue growth. Thyroid nodules usually develop as people get older, and they are much more common in women than in men. If you had radiation treatments to your head or neck as a child, you have an increased risk of developing a cancerous thyroid nodule.
Symptoms
A large thyroid nodule that contains functioning thyroid tissue may increase blood levels of thyroid hormones, causing symptoms of hyperthyroidism (see page 901) such as rapid heartbeat, trembling of the body and hands, increased sensitivity to heat, or sweating. A person may also have nail changes or bulging eyes and an intense, constant stare.
Diagnosis
Most thyroid nodules can be felt by a doctor during a physical examination. To evaluate the nodule, your doctor may perform a thyroid scan, which is a type of radionuclide scan (see page 114), in which you swallow a small amount of radioactive iodine and lie under a special camera that detects the radiation in the thyroid gland. Although a thyroid scan can detect nodules that contain functioning thyroid tissue, cancerous or fluid-filled nodules are not visible on the scan. Nodules that do not appear on a thyroid scan are usually evaluated by fine-needle aspiration, a diagnostic procedure in which a small amount of tissue and fluid are withdrawn from the nodule with a hollow needle and syringe and examined under a microscope for cancer cells.
Treatment
If a noncancerous nodule is small, your doctor may recommend monitoring it to see if it grows. If a fluid-filled nodule is large and unsightly, the doctor can reduce its size by removing some of the fluid with a needle and syringe. A nodule that contains functioning thyroid tissue can be destroyed by treatment with radioactive iodine. If a nodule is cancerous, the doctor will recommend surgery to remove the gland, and treatment with radioactive iodine to kill any remaining cancer cells. After the gland is removed, your doctor will monitor your condition regularly and you will need to take thyroid hormones for the rest of your life.
Hyperparathyroidism
Hyperparathyroidism is a disorder in which the parathyroid glands are overactive and produce too much parathyroid hormone. Along with vitamin D and a hormone called calcitonin produced by the thyroid gland, parathyroid hormone regulates the levels of calcium in the body. Overproduction of parathyroid hormone increases the amount of calcium circulating in the bloodstream by removing calcium from the bones. Loss of calcium from the bones can lead to osteoporosis (see page 989), a condition in which bones become weak and brittle and fracture easily. In an attempt to remove the excess calcium from the blood, the kidneys excrete greater-than-normal amounts of calcium in urine, which can lead to the formation of kidney stones (see page 814).
Hyperparathyroidism usually results from a small noncancerous tumor in one or more of the four parathyroid glands. In some cases, the disorder results from enlargement of the glands.