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Drug

Thyroid (Pork)

Summary of Interactions with Vitamins, Herbs, & Foods

  • Explanation Required

    4
    • Thyroid

      Calcium

      Needs Explanation

      This interaction is based on this drug belonging to a drug class. While this drug may differ from the text and references below, drugs within this class work in a similar way and this interaction is applicable to drugs within the same class.

      Thyroid hormones have been reported to increase urinary loss of calcium. However, recent research suggests that, under most circumstances, taking thyroid hormones may not be associated with reduced bone density. Calcium supplementation for people taking long-term thyroid medication has not yet been proven to be either helpful or necessary.

      Simultaneous ingestion of some calcium formulations with levothyroxine has been reported to reduce the effectiveness of levothyroxine. For example, 1,200 mg per day of calcium as calcium carbonate, taken along with levothyroxine, significantly reduced absorption of the thyroid hormone. Levothyroxine activity will not be blocked if it is taken in the morning and calcium carbonate is taken after lunch and dinner. Separating these medications by at least four hours is recommended.

      Calcium
      Thyroid
      ×
      1. Kung AWC, Pun KK. Bone mineral density in premenopausal women receiving long-term physiological doses of levothyroxine. JAMA 1991;265:2688-91.
      2. Schneider DL, Barrett-Connor EL, Morton DJ. Thyroid hormone use and bone mineral density in elderly men. Arch Intern Med 1995;155:2005-7.
      3. Franklyn JA, Betteridge J, Daykin J, et al. Long-term thyroxine treatment and bone mineral density. Lancet 1992;340:9-13.
      4. Schneyer CR. Calcium carbonate and reduction of levothyroxine efficacy. JAMA 1998;279:750.
      5. Singh N, Singh PN, Hershman JM. Effect of calcium carbonate on the absorption of levothyroxine. JAMA 2000;283:2822-5.
    • Thyroid (Pork)

      Calcium

      Needs Explanation

      This interaction is based on this drug belonging to a drug class. While this drug may differ from the text and references below, drugs within this class work in a similar way and this interaction is applicable to drugs within the same class.

      Thyroid hormones have been reported to increase urinary loss of calcium. However, recent research suggests that, under most circumstances, taking thyroid hormones may not be associated with reduced bone density. Calcium supplementation for people taking long-term thyroid medication has not yet been proven to be either helpful or necessary.

      Simultaneous ingestion of some calcium formulations with levothyroxine has been reported to reduce the effectiveness of levothyroxine. For example, 1,200 mg per day of calcium as calcium carbonate, taken along with levothyroxine, significantly reduced absorption of the thyroid hormone. Levothyroxine activity will not be blocked if it is taken in the morning and calcium carbonate is taken after lunch and dinner. Separating these medications by at least four hours is recommended.

      Calcium
      Thyroid (Pork)
      ×
      1. Kung AWC, Pun KK. Bone mineral density in premenopausal women receiving long-term physiological doses of levothyroxine. JAMA 1991;265:2688-91.
      2. Schneider DL, Barrett-Connor EL, Morton DJ. Thyroid hormone use and bone mineral density in elderly men. Arch Intern Med 1995;155:2005-7.
      3. Franklyn JA, Betteridge J, Daykin J, et al. Long-term thyroxine treatment and bone mineral density. Lancet 1992;340:9-13.
      4. Schneyer CR. Calcium carbonate and reduction of levothyroxine efficacy. JAMA 1998;279:750.
      5. Singh N, Singh PN, Hershman JM. Effect of calcium carbonate on the absorption of levothyroxine. JAMA 2000;283:2822-5.
    • Thyroid

      Iron

      Needs Explanation

      This interaction is based on this drug belonging to a drug class. While this drug may differ from the text and references below, drugs within this class work in a similar way and this interaction is applicable to drugs within the same class.

      Iron deficiency has been reported to impair the body’s ability to make its own thyroid hormones, which could increase the need for thyroid medication. In a preliminary trial, iron supplementation given to iron-deficient women with low blood levels of thyroid hormones, partially normalized these levels. Diagnosing iron deficiency requires the help of a doctor. The body’s ability to make its own thyroid hormones is also reduced during low-calorie dieting. Iron supplementation (27 mg per day) was reported in a controlled study to help maintain normal thyroid hormone levels in obese patients despite a very low-calorie diet.

      However, iron supplements may decrease absorption of thyroid hormone medications. People taking thyroid hormone medications should talk with their doctor before taking iron-containing products. If advised to supplement, iron and the drug should not be taken within less than four hours of each other.

      Iron
      Thyroid
      ×
      1. Beard JL, Borel MJ, Derr J. Impaired thermoregulation and thyroid function in iron-deficiency anemia. Am J Clin Nutr 1990;52:813-9.
      2. Beard J, Borel M, Peterson FJ. Changes in iron status during weight loss with very-low-energy diets. Am J Clin Nutr 1997;66:104-10.
      3. Campbell NR, Hasinoff BB. Iron supplements: A common cause of drug interactions. Br J Clin Pharmacol 1991;31:251-5.
      4. Campbell NR, Hasinoff BB, Stalts H, et al. Ferrous sulfate reduces thyroxine efficacy in patients with hypothyroidism. Ann Intern Med 1992;117:1010-3.
    • Thyroid (Pork)

      Iron

      Needs Explanation

      This interaction is based on this drug belonging to a drug class. While this drug may differ from the text and references below, drugs within this class work in a similar way and this interaction is applicable to drugs within the same class.

      Iron deficiency has been reported to impair the body’s ability to make its own thyroid hormones, which could increase the need for thyroid medication. In a preliminary trial, iron supplementation given to iron-deficient women with low blood levels of thyroid hormones, partially normalized these levels. Diagnosing iron deficiency requires the help of a doctor. The body’s ability to make its own thyroid hormones is also reduced during low-calorie dieting. Iron supplementation (27 mg per day) was reported in a controlled study to help maintain normal thyroid hormone levels in obese patients despite a very low-calorie diet.

      However, iron supplements may decrease absorption of thyroid hormone medications. People taking thyroid hormone medications should talk with their doctor before taking iron-containing products. If advised to supplement, iron and the drug should not be taken within less than four hours of each other.

      Iron
      Thyroid (Pork)
      ×
      1. Beard JL, Borel MJ, Derr J. Impaired thermoregulation and thyroid function in iron-deficiency anemia. Am J Clin Nutr 1990;52:813-9.
      2. Beard J, Borel M, Peterson FJ. Changes in iron status during weight loss with very-low-energy diets. Am J Clin Nutr 1997;66:104-10.
      3. Campbell NR, Hasinoff BB. Iron supplements: A common cause of drug interactions. Br J Clin Pharmacol 1991;31:251-5.
      4. Campbell NR, Hasinoff BB, Stalts H, et al. Ferrous sulfate reduces thyroxine efficacy in patients with hypothyroidism. Ann Intern Med 1992;117:1010-3.
The Drug-Nutrient Interactions table may not include every possible interaction. Taking medicines with meals, on an empty stomach, or with alcohol may influence their effects. For details, refer to the manufacturers’ package information as these are not covered in this table. If you take medications, always discuss the potential risks and benefits of adding a new supplement with your doctor or pharmacist.

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