ORLANDO – Consuming milk and levothyroxine 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.
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The total serum T4 absorption over 6 hours, calculated as area under the curve, was significantly lower when participants took levothyroxine and milk concurrently, compared with taking it alone (67.26 vs. 73.48; P equals .02).
The best interval between taking levothyroxine and drinking milk has yet to be established, according to Dr. Chon, who is on the faculty of the University of California, Los Angeles. Findings from earlier research showed that use of elemental calcium supplements interfere with absorption of levothyroxine.
In 2014, levothyroxine 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.
This article was updated 4/10/17.