Dosages and Side Effects of Synthroid
- Synthroid (levothyroxine sodium) is the brand name for a pharmaceutically produced version of the thyroid hormone thyroxine. Thyroid hormones increase and regulate metabolism of fats, carbohydrates and vitamins, affect protein synthesis and work with growth hormone to regulate bone growth. Because it interacts with most cells, thyroid hormone deficiency results in abnormal metabolism and development.
- Doctors prescribe Synthroid to treat low natural levels of thyroid hormone that may result from thyroid malfunction or atrophy, injury or damage to the pituitary gland or hypothalamus, surgery, radiation or the effects of other drugs. Doctors have also used Synthroid in patients suffering from thyroid cancer, those who have had their thyroid surgically removed or patients with a goiter (swelling of the thyroid).
- Dosages of Synthroid depend on a number of factors, including age, weight, previously measured thyroid hormone baseline (amount naturally found in blood), prior instance of disease, and the condition being treated.
For example, healthy patients under age 50 and patients older than 50 recently diagnosed with hypothyroidism (thyroid hormone deficiency) take daily replacement levels of 1.7 micrograms per kilogram of body weight (anywhere from 100 to 125 mcg for a 150 lb adult). Older patients might take less than one microgram per kilogram of body weight per day.
Patients under 50 who suffer from cardiac disease might start by taking only 25 to 50 micrograms per day, while those older than 50 who have cardiac disease might take as little as 12.5 to 25 micrograms daily.
For patients with severely low levels of thyroid hormone, the recommended dose is 12.5 to 50 micrograms daily, which will be adjusted upward by 25 micrograms every two to four weeks until dosages establish normal levels.
Otherwise, doctors adjust adult dosages in 12.5 to 25 microgram increments and may alter Synthroid administration, depending on how well the patient responds. Patients are advised to take the dosage recommend by their doctor, continue taking the medication during illness and refrain from altering the dosage. - Infants initially receive a recommended daily dose of 10 to 15 micrograms per kilogram of body weight. This dosage will be increased or decreased depending on how well the infant responds to treatment. Infants with severe hypothyroidism receive 50 micrograms daily.
The amount taken by children varies with age and body weight and is adjusted periodically until the child reaches puberty and can begin taking adult levels. - Patients are advised to take Synthroid in the morning, on an empty stomach 30 minutes before eating. Individuals should try to set up a routine where they take Synthroid at the same time every day.
- Patients are encouraged to dissolve Synthroid in 8 oz. of water, as this will aid absorption. Additionally, some foods can affect how well the body absorbs this medicine---patients should avoid eating any soy products within three hours or calcium or iron supplements within four hours of taking Synthroid. They should also avoid antacids that contain magnesium, which have been shown to reduce absorption of Synthroid.
- Synthroid can cause heart palpitations, edema (swelling of ankles), nervousness, headaches and insomnia. Some patients have also experienced weight loss and increased appetite.
In women, long-term use has been associated with a decrease in bone mineral density. Patients with pre-existing cardiac disease have experienced arrhythmia, increased heart rate and thickened heart walls.
An overdose of Synthroid may create effects ranging from fever and low blood sugar to serious conditions, such as heart failure and coma, that may result in fatality.
