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.
Too much of this type of vitamin A in your diet can cause birth defects in your developing baby, especially during the first months of pregnancy. The other type of vitamin A is called provitamin A carotenoids, which are found in fruits and vegetables.oo much of this type of vitamin A in your diet can cause birth defects in your developing baby, especially during the first months of pregnancy. The other type of vitamin A is called provitamin A carotenoids, which are found in fruits and vegetables.