Iodine ingested iodine and retain it for periods longer than this isotope's radiological half-life of eight days. For this reason, people at risk of exposure to environmental radioactive iodine (iodine-131) in fallout may be instructed to take non-radioactive potassium iodide tablets. The typical adult dose is one 130 mg tablet per 24 hours, supplying 100 mg (100,000 micrograms) of ionic iodine. (The typical daily dose of iodine for normal health is of order 100 micrograms; see "Dietary Intake" below.) Ingestion of this large dose of non-radioactive iodine minimises the uptake of radioactive iodine by the thyroid gland. As an element with
Absent adrenal gland Absent adrenal gland Absent adrenal gland is a rare condition where the adrenal gland is absent at birth. It should not be confused with adrenal insufficiency or congenital adrenal hyperplasia, where the gland is present but may not be functioning adequately. Due to the absence of adrenal cortex, the condition causes extreme symptoms of adrenal insufficiency at birth due to very low levels of aldosterone and cortisol. The adrenal medulla can be normally present, poorly formed, or absent, however even so the effects of circulatory catecholamine deficiency are generally mild (due to sympathetic nervous system compensation), except in episodes of