How does levothyroxine work?
The thyroid gland in your neck makes a hormone called thyroxine. Thyroxine controls how much energy your body uses (the metabolic rate). It’s also involved in digestion, how your heart and muscles work, brain development and bone health.
When the thyroid gland does not make enough thyroxine (called hypothyroidism), many of the body’s functions slow down. Some of the most common symptoms of an underactive thyroid gland are:
- tiredness
- feeling cold
- difficulty concentrating
- weight gain
- feeling depressed
Levothyroxine is a synthetic version of thyroxine. You take levothyroxine tablets to replace the thyroxine that your thyroid gland cannot produce and prevent the symptoms of hypothyroidism. Levothyroxine is a medicine used to treat an underactive thyroid gland (hypothyroidism).
Cautions with other medicines
It has long been known that many foods and medications – including calcium supplements, soy, and iron—interfere with the absorption of oral levothyroxine in the body. Changes in the amount of levothyroxine absorbed can lead to changes in thyroid blood tests used to monitor the appropriateness of its dose.
The researchers believe that both the calcium content of the milk and the presence of protein might directly interfere with the proper and full absorption of levothyroxine, complicating the management of hypothyroid.
Calcium-rich foods including cow’s milk, yogurt, cheeses (eg, ricotta, cottage, cheddar, American) and ice cream and frozen yogurt. Also, non-dairy milk like those made from almond, soy, and rice, which are fortified with calcium.
