What are the Different Types of Iodine Test?

Iodine is essential to healthy nutrition and also regulates thyroid hormone production. Different types of iodine test can detect the presence of starch in common foods, look for cervical cancer cells, and test thyroid health. Starch and patch tests can be performed at home, while cervical cancer, iodine urine, and radioactive iodine uptake tests must be done by medical professionals.

The starch iodine test detects starches in tubers and grains. This iodine test is performed by dropping an iodine solution directly on the flesh of a potato or on grain products, such as bread or crackers. If there is starch, the solution will turn blue-black. If there is no starch, the solution will stay its original orange or yellow color.

Iodine deficiency is a medical condition that can cause lack of energy, fatigue, edginess, and listlessness, and can be overlooked by medical professionals because it mirrors the symptoms of depression and stress. The patch iodine test can be performed at home to detect iodine deficiency. A 3 inch (7.62 cm) square patch of a tincture of iodine is painted on the belly or upper thigh. Over a 24 hour period, the patch is then checked to see how long it takes to fade. If the patch has faded less than 24 hours, this indicates an iodine deficiency.

Cervical cancer cells can also be detected by an iodine test. If abnormalities are found in a routine pap smear, the doctor may recommend a colposcopy, also known as Schiller's test. In this test, an iodine solution is applied to the cervix and cervical canal. If the tissue is healthy, it will stain brown; if there is unhealthy tissue, it will remain white or yellow. The doctor will then order a biopsy to rule out cancer.

Monitoring thyroid health and detecting thyroid disease can also be done by an iodine test. In the iodine urine test, the patient collects a urine sample in the morning, which is used as the control. She will then take 50 milligrams of iodine orally, and urine is collected periodically over the next 24 hours. If iodine levels are good, over 90 percent of the iodine will be in the urine.

The radioactive iodine uptake test is used to diagnose and prescribe treatments for hyperthyroid conditions. The patient swallows a dose of radioactive iodine in either capsule or liquid form. Four to six hours later, a radiation scan of the thyroid is performed, and performed again 24 hours later. Low iodine uptake indicates hyperthyroidism caused by inflammation or too much thyroid hormone replacement medications, and a high iodine uptake indicates Graves' or Hashimoto's disease. Irregular uptake usually indicates hyperthyroidism caused by a goiter or tumor.