Can Synthroid Taken for Hypothyroidism Cause Osteoporosis?

Last Editorial Review: 1/11/2018

Ask the Experts

Is there a relationship between synthroid taken for hypothyroidism and osteoporosis? Can synthroid make bone loss worse?

Doctor's Response

Osteoporosis is defined as "a disease characterized by low bone mass and microarchitectural deterioration of bone tissue leading to enhanced fragility and increased fracture risk". There are a number of contributors to osteoporosis, including genetics, peak bone mass acquired during youth, and factors that contribute to increased breakdown of bone and/or a decrease in formation of new bone. Hyperthyroidism itself produces an increase in bone loss, and if the disease is treated early, this can be minimized. In the same manner, excessive amounts of thyroid hormone replacement can result in bone loss. For this reason, it is important that patients on thyroid hormone replacement be checked regularly ( every 6-12 months) to make certain that the dose of replacement results in a TSH within a normal range. The only exception to this rule is when treating patients on replacement after their thyroid is removed or destroyed secondary to cancer. In these cases, the amount of replacement given is greater, and results in a suppression of TSH. If you have concerns about your bone density, you should speak with your physician about ways to assess your bone mass (a bone density test). In addition, you should seek out information on ways to maintain healthy bones such as calcium supplementation and weight bearing exercises. If your bone density is actually low, there are many therapies out there to treat osteoporosis. These treatments can be given while continuing on your thyroid replacement regimen.

Ask the Expert

I am breastfeeding and will be visiting Africa soon. I have been told that I need to take a drug against malaria. Will that be bad for my baby?

Doctor's Response

The U.S. Centers for Disease Control and Prevention (the CDC) recommends that you "Take Your Antimalarial While Breastfeeding."

The CDC states further that: "If you are breastfeeding, a very small amount of antimalarial will be passed into your breast milk. This small amount of drug will neither harm your infant nor be enough to protect him or her against malaria. Infants need to be given their own antimalarial medicine. Recommended antimalarial dosages for infants and children are listed in fax document number 380012 and at http:\\\travel\mal_kids_pub.htm."

Carolyn Janet Crandall, M.D.
Editor:   William Shiel, MD, FACP, FACR