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 is a particular danger for pregnant women, who are therefore advised not to eat liver, which is a rich source of Vitamin A. Vitamin A is stored in the human liver too and overdose occurs when the liver's ability to store it is exceeded, and the excess enters the bloodstream.he dose at which Vitamin D begins to become dangerous is a sustained intake of more than 1, 250 micrograms daily for several weeks, in adults, although lower doses are dangerous in children and fetuses and pregnant women are advised to consult a doctor before taking Vitamin D supplements.