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Cited by 34Thyroid Disorders and TreatmentsPharmacogenetics and Drug MetabolismDrug Solubulity and Delivery Systems

Concurrent milk ingestion decreases absorption of levothyroxine

Open access
Chon, Deborah A., Reisman, Tamar, Weinreb, Jane E., Hershman, Jerome M., Leung, Angela M.·2018·Thyroid
DOI 10.1089/thy.2017.0428PMC PMC5905419
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Abstract

BACKGROUND: Levothyroxine is the most commonly prescribed medication in the United States. Many foods and medications, including calcium supplements, can interfere with levothyroxine absorption. No studies have investigated the effect of cow's milk, a common breakfast staple, on the absorption of oral levothyroxine. Cow's milk contains approximately 450 mg of elemental calcium per 12 oz (355 mL) serving. METHODS: A pharmacokinetic study was conducted in healthy euthyroid subjects to assess levothyroxine absorption with and without concurrent cow's milk consumption. Following an overnight fast, serum total thyroxine (TT4) concentrations were measured at baseline and at one, two, four, and six hours after ingestion of 1000 μg of oral levothyroxine alone or when co-administered with 12 oz (355 mL) of 2% milk. There was a four-week washout period between the two assessments in each subject. RESULTS: ± SD = 33.7 ± 10.2 years; 60% male) completed the study. The area under the curve (AUC) of TT4 concentrations was significantly lower when levothyroxine was ingested along with 12 oz (355 mL) of 2% cow's milk (M ± SD = 67.3 ± 12.1) compared to that with levothyroxine alone (73.5 ± 17.0; p = 0.02). Also, peak serum TT4 concentrations were significantly lower when cow's milk was co-administered with levothyroxine (M ± SD = 14.1 ± 0.8 μg/dL) than with levothyroxine alone (13.0 ± 0.9 μg/dL; p = 0.04). CONCLUSIONS: This is the first study to demonstrate that concurrent cow's milk ingestion reduces oral levothyroxine absorption. The findings support previous literature showing the interference of elemental calcium and food with thyroid hormone absorption. Patients managed with thyroid hormone should be advised to avoid taking their levothyroxine simultaneously with cow's milk.

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  • In a study of ten healthy patients, peak serum T4 concentrations and AUC were significantly lower when LT4 was taken simultaneously with cow's milk (containing 450 mg calcium) compared to LT4 alone.

    “Peak serum T4 concentrations and area under the curve (AUC) were found to be significantly lower in patients taking LT4 simultaneously with cow’s milk (containing 450 mg calcium) as compared to ingestion of LT4 alone (54).”

    From ETA guidelines for the use of levothyroxine sodium preparations in monotherapy to optimize the treatment of hypothyroidism (2025) · cites this paper as [54]

  • In Chon et al. pharmacokinetic study, co-administration of LT4 and 2% milk by healthy euthyroid subjects was associated with significantly lower peak concentration (by around 8%) and significantly lower area under curve for TT4 (10%).

    “In Chon et al. pharmacokinetic study of cold or hot milk (another beverage frequently consumed at breakfast), co-administration of LT4 and 2% milk by healthy euthyroid subjects was associated with a significantly lower peak concentration (by around 8%) and a significantly lower area under the curve for TT4 (10%) [ 80 ].”

    From Factors influencing the levothyroxine dose in the hormone replacement therapy of primary hypothyroidism in adults (2022) · cites this paper as [80]

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Authors
Chon, D. A., Reisman, T., Weinreb, J. E., Hershman, J. M., & Leung, A. M.
Affiliations
University of California, Los Angeles (US)
Corresponding author
Leung, Angela M.
ORCID
Leung, Angela M.
Venue
Thyroid
Publisher
SAGE Publications
Published
2018-04
Volume
28
Issue
4
Pages
454-457
ISSN
  • 1050-7256 (ISSN-L)
  • 1557-9077
DOI
10.1089/thy.2017.0428
PMC
PMC5905419
OpenAlex
W2790683935
Cited by
34
References
26
Citations by year
2026: 3 · 2025: 4 · 2024: 2 · 2023: 6 · 2022: 7 · 2021: 5 · 2020: 2 · 2019: 1 · 2018: 3
FWCI
2.19
Type
journal article
Language
en
Open access
Licence
www.liebertpub.com/nv/resources-tools/text-and-data-mining-policy/121/ (tdm)
Locations
  • Thyroid (publishedVersion)
  • Europe PMC (PubMed Central) (publishedVersion)
  • PubMed Central (publishedVersion)
  • PubMed (publishedVersion)
  • eScholarship (California Digital Library) (submittedVersion)
Funders
  • National Institutes of Health
  • Eunice Kennedy Shriver National Institute of Child Health and Human Development (K23HD068552)
Topics
  • Health Sciences › Medicine › Endocrinology, Diabetes and Metabolism › Thyroid Disorders and Treatments
  • Life Sciences › Pharmacology, Toxicology and Pharmaceutics › Pharmacology › Pharmacogenetics and Drug Metabolism
  • Life Sciences › Pharmacology, Toxicology and Pharmaceutics › Pharmaceutical Science › Drug Solubulity and Delivery Systems
Keywords
levothyroxine, cow's milk, drug absorption, food-drug interactions, calcium interference, thyroid hormones, total thyroxine, pharmacokinetics
MeSH terms
Adult, Animals, Female, Humans, Intestinal Absorption, Male, Milk, Thyroxine, Young Adult

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