The mean daily thyroxine dose was 1.99 mcg/kg (range, 0.3 to 6.6 mcg/kg) with a mean duration of therapy of 20.4 years (range, less than 1 to 68 years). Women taking daily doses of 1.6 mcg/kg or more had significantly lower bone mineral density levels at the ultradistal radius, midshaft radius, hip, and lumbar spine compared to controls. However, estrogen use appeared to negate the adverse. Thyroid hormones are two hormones produced and released by the thyroid gland, namely triiodothyronine (T 3) and thyroxine (T 4). They are tyrosine -based hormones that are primarily responsible for regulation of metabolism. Thyroxine has a very long half-life. Because of this, it doesn’t matter very much what time of day it’s taken. Each dose contributes just a small amount to the total level. How to use L-Thyroxine Sodium Tablet. Read the Patient Information Leaflet if available from your pharmacist before you start taking levothyroxine and each time you get a refill. One of those hormones is thyroxine, also known as T4. Because of the many functions that thyroxine impacts, it is considered one of the most important thyroid hormones. Understanding thyroxine is crucial to protecting your overall health. What other drugs will affect levothyroxine? Many other medicines can be affected by your thyroid hormone levels. Certain other medicines may also increase or decrease the effects of levothyroxine. Synthroid (levothyroxine sodium) tablets, for oral use is a prescription, man-made thyroid hormone that is used to treat a condition called hypothyroidism. Thyroxine is the main hormone secreted into the bloodstream by the thyroid gland. It plays vital roles in digestion, heart and muscle function, brain development and maintenance of bones. It plays vital roles in digestion, heart and muscle function, brain development and maintenance of bones. How to use L-Thyroxine Tablet. Read the Patient Information Leaflet if available from your pharmacist before you start taking levothyroxine and each time you get a refill. Medical use. Levothyroxine is typically used to treat hypothyroidism, and is the treatment of choice for people with hypothyroidism, who often require lifelong thyroid hormone therapy. Doses of levothyroxine that normalize serum TSH may not normalize LDL cholesterol and total cholesterol.