Send to:

Choose Destination
See comment in PubMed Commons below
South Med J. 1997 Jun;90(6):637-9.

Ferrous sulfate-induced increase in requirement for thyroxine in a patient with primary hypothyroidism.

Author information

  • 1Department of Internal Medicine, National Naval Medical Center, Bethesda, MD 20889-5600, USA.


Recent studies have shown that under experimental conditions ferrous sulfate may reduce the gastrointestinal absorption of orally administered levothyroxine sodium in patients with primary hypothyroidism. We describe a patient who became hypothyroid while taking ferrous sulfate. The hypothyroid status was corrected by increasing the dose of levothyroxine. Subsequently, when ferrous sulfate was discontinued, the patient became hyperthyroid while taking the higher dose of thyroid hormone preparation. Since both hypothyroidism and iron deficiency anemia may coexist, additional thyroid function testing is recommended in patients treated concurrently with ferrous sulfate and L-thyroxine.

[PubMed - indexed for MEDLINE]
PubMed Commons home

PubMed Commons

How to join PubMed Commons

    Supplemental Content

    Loading ...
    Write to the Help Desk