Hvis legen din måler kun FT4 og TSH, mens du gjerne også vil ha målt FT3. Les denne artikkelen og ta den med til legen din http://med.miami.edu/news/new-miller...mone-indicato/
Clinicians typically evaluate the health of a thyroid by measuring the levels of T4 and thyroid-stimulating hormone (TSH), which is produced by the pituitary gland under the control of the thyrotropin-releasing hormone (TRH) made by the hypothalamus. “When you have a thyroid that doesn’t work as much as it should, the thyroid hormone levels in the plasma go down and the TSH levels go up; the opposite happens when you have an excess of thyroid hormones, and the TSH levels will be very low and the thyroid hormones will be high,” said Bianco. “Although we understand the overall principles of this hormone feedback mechanism, many details that have clinical significance are still missing.”
In the laboratory study, the Miller School research team focused on the role of an enzyme called Type II deiodinase (D2) produced in the hypothalamus and pituitary that converts the less active T4 to the highly active T3 hormone. “The question is important for clinicians, because plasma T4 must be converted to T3 in order to be detected by the pituitary gland and decrease TSH secretion,” Bianco said. “We wanted to understand the relative roles played by pituitary versus hypothalamic D2 in the thyroid hormone-mediated feedback mechanism.”
Using new mouse strains developed at the Miller School as an experimental model, Bianco and his team found that inactivating the D2 enzyme in the pituitary gland produced major changes in TRH, TSH and T4 levels, but did not affect T3 levels in the plasma. “This finding clearly shows that the body’s endocrine system is wired to keep plasma T3 in the normal range,” he said. “It also points to the importance of T3 as a clinical indicator in the follow-up of hypothyroid patients who are being treated with levothyroxine.”
“We know that about 20 percent of hypothyroid patients treated with levothyroxine are not happy despite having normal plasma T4 and TSH levels,” Bianco said, “and many of these patients exhibit lower plasma levels of T3. Other hypothyroid patients don’t complain to their doctors, but could potentially benefit as well from more effective treatments that normalize plasma T3, potentially making it easier to lose weight or maintain their mental focus.”