Enter the patient’s body weight (kg or lbs) to calculate the full oral thyroid replacement dose of levothyroxine for the treatment of hypothyroidism. Learn about Synthroid (levothyroxine) dosage, including starting doses, dosage charts for adults and children, adjustments, and how to take it safely. Synthroid (levothyroxine) is a prescription drug used to treat hypothyroidism and to suppress TSH. Learn about the drug’s dosages, strengths, and more. Are you on Levothyroxine but still experiencing symptoms of Hypothyroidism? Use this dosage guide to help you find how much you should be taking. Detailed Levothyroxine dosage information for adults, the elderly and children. Includes dosages for Hypothyroidism, TSH Suppression and Myxedema Coma; plus renal, liver and dialysis adjustments. Detailed dosage guidelines and administration information for Synthroid (levothyroxine sodium). Includes dose adjustments, warnings and precautions. Medscape - Hypothyroidism-specific dosing for Synthroid, Levoxyl (levothyroxine), frequency-based adverse effects, comprehensive interactions, contraindications, pregnancy & lactation. The dose is usually 1.7 microgram (mcg) per kilogram (kg) of body weight per day but may be less in older adults. Children older than 12 years of age (growth and puberty incomplete)—Dose is based on body weight and must be determined by your doctor. Take SYNTHROID as a single dose, preferably on an empty stomach, one-half to one hour before breakfast. Once your doctor has found your specific SYNTHROID dose, it is important to have periodic lab tests and clinical evaluations to assess your treatment response. View SYNTHROID® 12 precise dosing options. Find SYNTHROID® dose calculations, adjustments, guidelines, and food & drug interactions here.