AT ENDO 2017

ORLANDO (FRONTLINE MEDICAL NEWS) – Consuming milk and levothyroxin at the same time reduced the absorption of the thyroid hormone replacement, according to Deborah Chon, MD, speaking at a press briefing at the annual meeting of the Endocrine Society.

This finding comes from a small study of 10 healthy adults with normal TSH concentration at baseline. The study participants had a mean age of 34 years and 6 were men.

Following an overnight fast, researchers measured the subjects’ serum total thyroxin T4 (TT4) to serve as the baseline. TT4 was remeasured 1, 2, 4, and 6 hours after ingestion of 1,000 μg of oral levothyroxin alone or given together with 12 ounces of 2% milk, a common breakfast drink. After a 4 week washout, participants crossed over to the other protocol.

The total serum T4 absorption over 6 hours, calculated as area under the curve, was significantly lower when participants took levothyroxin and milk concurrently compared with taking it alone (67.26 vs. 73.48; P equals .02).

The best interval between taking levothyroxin and drinking milk has yet to be established, according to Dr. Chon, who is on the faculty of the UCLA David Geffen School of Medicine in Los Angeles. Findings from earlier research showed that use of elemental calcium supplements interfere with absorption of levothyroxin.

In 2014, levothyroxin became the most commonly prescribed drug in the United States, according to a survey by the IMS Institute for Healthcare Informatics, now QuintilesIMS. Patients who need to take it because of Hashimoto’s thyroiditis or after thyroidectomy are often unhappy with how they feel. Dose adjustments are common as endocrinologists struggle to improve patients’ quality of life. It may be that a simple strategy of not taking the thyroid replacement at the same time as milk might leave patients feeling better.

Dr. Chon reported having no relevant financial conflicts of interest.