Thyroid function tests are blood tests that check the levels of the hormones (chemicals) made by the thyroid gland. Some thyroid function tests also check the level of a hormone made by the pituitary gland in the brain, which acts on the thyroid gland.hyroid function tests are blood tests that check the levels of the hormones (chemicals) made by the thyroid gland. Some thyroid function tests also check the level of a hormone made by the pituitary gland in the brain, which acts on the thyroid gland.
Yes, high intakes of some forms of vitamin A can be harmful. Getting too much preformed vitamin A (usually from supplements or certain medicines) can cause dizziness, nausea, headaches, coma, and even death. High intakes of preformed vitamin A in pregnant women can also cause birth defects in their babies.
Hypervitaminosis A, or vitamin A toxicity, occurs when you have too much vitamin A in your body. This condition may be acute or chronic. Acute toxicity occurs after consuming large amounts of vitamin A over a short period of time, typically within a few hours or days. Chronic toxicity occurs when large amounts of vitamin A build up in the body over a long period of time. Symptoms include visual changes, bone pain, and skin changes. Chronic toxicity can lead to liver damage and increased pressure on the brain.