Last update Aug. 26, 2022

Levothyroxine

Compatible

Safe substance and/or breastfeeding is the best option.

Levothyroxine is the synthetic form of the hormone thyroxine (T4) secreted by the thyroid gland. It is indicated as therapy for congenital or acquired hypothyroidism and as a complement in thyrotropin-dependent thyroid cancer. Oral administration.

Maternal endogenous T4 is excreted naturally in breast milk (Vass 2022, Mallya 2018), but in very small amounts, insufficient to protect a breastfed baby with congenital hypothyroidism (van Wassenaer 2002, Mizuta 1983, Mallol 1982, Letarte 1980, Sato 1979, Sack 1977), although it might alleviate symptoms. (Bode 1978)

Administration of exogenous T4 does not significantly alter T4 levels in breast milk (Zhang 2013). The risk of using exogenous T4 is the same as that of an untreated euthyroid mother. (Hale)

No problems have been seen in infants whose mothers were taking T4. (Mungan 2016, Ito 1993, Caplan 1993)

Treatment with T4 in hypothyroid mothers does not pose a risk to the infant. Nursing mothers with hypothyroidism, even subclinical, should be treated with T4. (Alexander 2017)

Breastfeeding does not alter the infant's thyroid function or T4 levels. (van Wassenaer 2002, Franklin 1985, Abbassi 1980, Varma 1978)

Various medical societies and expert authors consider the use of this medication to be safe during lactation(Hale, Alexander 2017, Serrano 2015, Briggs 2015, Stagnaro 2011). Recommendations for Drugs in the Eleventh WHO Model List of Essential Drugs: compatible with Breastfeeding (WHO 2002). American Academy of Pediatrics: medication usually compatible with breastfeeding. (AAP 2001)


See below the information of these related products:

Alternatives

We do not have alternatives for Levothyroxine since it is relatively safe.

Suggestions made at e-lactancia are done by APILAM team of health professionals, and are based on updated scientific publications. It is not intended to replace the relationship you have with your doctor but to compound it. The pharmaceutical industry contraindicates breastfeeding, mistakenly and without scientific reasons, in most of the drug data sheets.

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Other names

Levothyroxine is also known as


Levothyroxine in other languages or writings:

Group

Levothyroxine belongs to this group or family:

Tradenames

Main tradenames from several countries containing Levothyroxine in its composition:

List of 25 tradenames
  • Bitiron™. Contains other elements than Levothyroxine in its composition
  • Combithyrex™. Contains other elements than Levothyroxine in its composition
  • Cynoplus™. Contains other elements than Levothyroxine in its composition
  • Dexnon™
  • Diotroxin™. Contains other elements than Levothyroxine in its composition
  • Dithyron™. Contains other elements than Levothyroxine in its composition
  • Eltroxin™
  • Euthyral™. Contains other elements than Levothyroxine in its composition
  • Euthyrox Эутирокс™
  • Eutirox™
  • Eutroid™. Contains other elements than Levothyroxine in its composition
  • Levaxin™
  • Levothroid™
  • Levotrin™. Contains other elements than Levothyroxine in its composition
  • Liotrix Tablets USP 39™. Contains other elements than Levothyroxine in its composition
  • Novothyral™. Contains other elements than Levothyroxine in its composition
  • Novotiral™. Contains other elements than Levothyroxine in its composition
  • Oroxine™
  • Prothyrid™. Contains other elements than Levothyroxine in its composition
  • Synthroid™
  • Tetroid™
  • Thyrolar™. Contains other elements than Levothyroxine in its composition
  • Tiroide Amsa™. Contains other elements than Levothyroxine in its composition
  • Tirosint™
  • Tiroxina™

Pharmacokinetics

Variable Value Unit
Oral Bioavail. 40 - 80 %
Molecular weight 790 daltons
Protein Binding 99 %
Tmax 4 hours
T½ 144 - 168 hours
M/P ratio 0.3 -
Theoretical Dose <0.0001 mg/Kg/d
Relative Dose 0.05 %
Ped.Relat.Dose 0.01 %

References

  1. Hale TW. Medications & Mothers' Milk. 1991- . Springer Publishing Company. Available from https://www.halesmeds.com Consulted on April 10, 2024 Full text (link to original source)
  2. Vass RA, Kiss G, Bell EF, Miseta A, Bódis J, Funke S, Bokor S, Molnár D, Kósa B, Kiss AA, Takács T, Dombai F, Ertl T. Thyroxine and Thyroid-Stimulating Hormone in Own Mother's Milk, Donor Milk, and Infant Formula. Life (Basel). 2022 Apr 14;12(4). pii: 584. Consulted on Aug. 26, 2022 Abstract Full text (link to original source)
  3. Mallya M, Ogilvy-Stuart AL. Thyrotropic hormones. Best Pract Res Clin Endocrinol Metab. 2018 Jan;32(1):17-25. Abstract
  4. Alexander EK, Pearce EN, Brent GA, Brown RS, Chen H, Dosiou C, Grobman WA, Laurberg P, Lazarus JH, Mandel SJ, Peeters RP, Sullivan S. 2017 Guidelines of the American Thyroid Association for the Diagnosis and Management of Thyroid Disease During Pregnancy and the Postpartum. Thyroid. 2017 Abstract Full text (link to original source) Full text (in our servers)
  5. Mungan NÖ, Kör D, Büyükkurt S, Atmış A, Güleç Ü, Satar M. Propionic acidemia: a Turkish case report of a successful pregnancy, labor and lactation. J Pediatr Endocrinol Metab. 2016 Jul 1;29(7):863-6. Abstract
  6. Serrano Aguayo P, García de Quirós Muñoz JM, Bretón Lesmes I, Cózar León MV. Tratamiento de enfermedades endocrinológicas durante la lactancia. [Endocrinologic diseases management during breastfeeding.] Med Clin (Barc). 2015 Jan 20;144(2):73-9. Abstract
  7. Briggs GG, Freeman RK, Towers CV, Forinash AB. Drugs in Pregnancy and Lactation: A Reference Guide to Fetal and Neonatal Risk. Wolters Kluwer Health. Tenth edition (acces on line) 2015
  8. Zhang Q, Lian XL, Chai XF, Bai Y, Dai WX. [Relationship between maternal milk and serum thyroid hormones in patients with thyroid related diseases]. Zhongguo Yi Xue Ke Xue Yuan Xue Bao. 2013 Abstract
  9. Stagnaro-Green A, Abalovich M, Alexander E, Azizi F, Mestman J, Negro R, Nixon A, Pearce EN, Soldin OP, Sullivan S, Wiersinga W; American Thyroid Association Taskforce on Thyroid Disease During Pregnancy and Postpartum.. Guidelines of the American Thyroid Association for the diagnosis and management of thyroid disease during pregnancy and postpartum. Thyroid. 2011 Abstract Full text (link to original source) Full text (in our servers)
  10. Nice FJ, De Eugenio D, Dimino TA, Freeny IC, Rovnack MB, Gromelski JS. Medications and Breast-Feeding: A Guide for Pharmacists, Pharmacy Technicians, and Other Healthcare Professionals. Part I. J Pharm Technol 2004;20:17-27. doi: 10.1177/875512250402000106.
  11. van Wassenaer AG, Stulp MR, Valianpour F, Tamminga P, Ris Stalpers C, de Randamie JS, van Beusekom C, de Vijlder JJ. The quantity of thyroid hormone in human milk is too low to influence plasma thyroid hormone levels in the very preterm infant. Clin Endocrinol (Oxf). 2002 May;56(5):621-7. Abstract
  12. WHO / UNICEF. BREASTFEEDING AND MATERNAL MEDICATION Recommendations for Drugs in the Eleventh WHO Model List of Essential Drugs. Department of Child and Adolescent Health and Development (WHO/UNICEF) 2002 Abstract Full text (link to original source) Full text (in our servers)
  13. AAP - American Academy of Pediatrics Committee on Drugs. Transfer of drugs and other chemicals into human milk. Pediatrics. 2001 Sep;108(3):776-89. Abstract Full text (link to original source) Full text (in our servers)
  14. Caplan RH, Wickus GG. Reduced calcitriol requirements for treating hypoparathyroidism during lactation. A case report. J Reprod Med. 1993 Abstract
  15. Ito S, Blajchman A, Stephenson M, Eliopoulos C, Koren G. Prospective follow-up of adverse reactions in breast-fed infants exposed to maternal medication. Am J Obstet Gynecol. 1993 May;168(5):1393-9. Abstract
  16. Franklin R, O'Grady C, Carpenter L. Neonatal thyroid function: comparison between breast-fed and bottle-fed infants. J Pediatr. 1985 Jan;106(1):124-6. No abstract available. Abstract
  17. Mizuta H, Amino N, Ichihara K, Harada T, Nose O, Tanizawa O, Miyai K. Thyroid hormones in human milk and their influence on thyroid function of breast-fed babies. Pediatr Res. 1983 Abstract
  18. Mallol J, Obregón MJ, Morreale de Escobar G. Analytical artifacts in radioimmunoassay of L-thyroxin in human milk. Clin Chem. 1982 Abstract Full text (link to original source) Full text (in our servers)
  19. Abbassi V, Steinour TA. Successful diagnosis of congenital hypothyroidism in four breast-fed neonates. J Pediatr. 1980 Aug;97(2):259-61. No abstract available. Abstract
  20. Letarte J, Guyda H, Dussault JH, Glorieux J. Lack of protective effect of breast-feeding in congenital hypothyroidism: report of 12 cases. Pediatrics. 1980 Apr;65(4):703-5. Abstract
  21. Sato T, Suzuki Y. Presence of triiodothyronine, no detectable thyroxine and reverse triiodothyronine in human milk. Endocrinol Jpn. 1979 Abstract
  22. Bode HH, Vanjonack WJ, Crawford JD. Mitigation of cretinism by breast-feeding. Pediatrics. 1978 Abstract
  23. Varma SK, Collins M, Row A, Haller WS, Varma K. Thyroxine, tri-iodothyronine, and reverse tri-iodothyronine concentrations in human milk. J Pediatr. 1978 Abstract
  24. Sack J, Amado O, Lunenfeld B. Thyroxine concentration in human milk. J Clin Endocrinol Metab. 1977 Abstract

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