Inclusion criteria:
Age of 18 to 65 years
Hypothyroid patients with a history of treatment for more than one year using levothyroxine (sodium)
TSH is at least one year with a constant dose of levothyroxine in the normal range
No smoking and alcohol
Non pregnant, non-lactating
Non-use of drugs that affect metabolism and absorption of levothyroxine include: iron sulfate, magnesium sulfate, warfarin, luvastatin, amiodarone, sumatropin, calcium carbonate, orlistat, multivitamin and minerals, theophylline, ritunavir, rifampin, phenytoin, karmazapine, Phenobarbital, Sucralfate, Aluminum hydroxide, Sertraline, Bile doses, Estrogens and other estrogen modifying drugs, Proton pump suppressants, Phosphate binders
People who, after explaining the work, were willing to cooperate and answer questions and conduct experiments
Exclusion criteria:
Thyroid cancer
Intestinal malabsorption (history of obstructive surgery, inflammatory bowel disease, celiac disease)
Antibiotic use
Acute and chronic infectious diseases
Use of drugs that affect the absorption and metabolism of levothyroxine, including (iron sulfate, magnesium sulfate, warfarin, luvastatin, amiodarone, sumatropin, calcium carbonate, orlistat, multivitaminomineral, theophylline, ritunavir, rifampin, Tween, Karmazpine, Phenobarbital, Sucralfate, Aluminum Hydroxide, Sertraline, Bile Drug, Estrogen and other estrogen modifying drugs, proton pump inhibitor drugs, phosphate binders)