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.
Vitamin A overdose: Introduction. Excessive Vitamin A intake usually occurs through consumption of large amounts of Vitamin A supplements. Vitamin A is used in the body for vision, immunity and bone and tissue growth and maintenance. Excessive Vitamin A use during pregnancy may increase the risk of birth defects. Vitamin A overdose can cause symptoms such as orange skin, blurred vision and nausea.