Calcium pills are a useful dietary supplement for those who are concerned about getting enough of this important mineral. If you must also take levothyroxine, a commonly prescribed thyroid pill, you should be aware of a potential interaction between calcium supplements and this drug. Follow your doctor's recommendations carefully as to when and how to take your medication and any necessary dietary supplements.
Calcium
There is more calcium in your body than any other mineral. Stored largely in the teeth and bones, calcium is essential for maintaining the strength and hardness of your skeletal system. Calcium needs vary, depending on your age and sex, with young children and teenagers requiring the most. Sufficient calcium intake is a particular concern for women after they reach menopause, when they are most vulnerable to devastating fractures precipitated by bone loss. Dairy products such as milk, yogurt and cheese are rich dietary sources of this mineral. Calcium can also be found in leafy green vegetables like spinach. If you cannot take in sufficient amount of calcium through your diet, your doctor will most likely recommend that you take a calcium supplement.
Thyroid Medication
The most common thyroid medication is levothyroxine, sold under such brand names as Synthroid, Levoxyl and Unithroid. Levothyroxine is a synthetically produced thyroid hormone, chemically identical to the hormone produced by a healthy thyroid gland. Doctors prescribe this medication for patients whose thyroids produce an insufficient amount of hormone, and for those who have had a thyroidectomy due to cancer or other disease.
Interaction Between Calcium and Thyroid Medication
While calcium absorption remains unaffected by levothyroxine, the opposite is not true. Calcium, along with certain medications and other dietary supplements such as iron, has a negative effect on your body’s ability to properly absorb the hormone. A study performed at the Department of Endocrinology and Metabolism of the Veterans Affairs Greater Los Angeles Healthcare System in California found that calcium administered at the same time as levothyroxine reduced the thyroid drug’s absorption from 83.7 percent to 57.9 percent.
Recommendations for Taking Thyroid Medication and Calcium
Because levothyroxine should be taken on an empty stomach, it is best taken first thing in the morning. You should not eat or drink anything other than water for 30 to 60 minutes after taking thyroid hormone. If you also take calcium, your doctor will likely instruct you to allow at least four hours to pass after taking thyroid medication before you take calcium. The two main types of calcium supplements are calcium citrate and calcium carbonate. Although calcium citrate can be taken with or without food, calcium carbonate is best absorbed when taken with a meal. Because your body cannot absorb more than about 500 mg of calcium at any one time, you should split a larger dose over the day.
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