Levothyroxine and hair loss

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Levothyroxine and Hair Loss: Understanding the Connection

Introduction to Levothyroxine and Its Uses

Levothyroxine, a synthetic form of the thyroid hormone thyroxine, is commonly prescribed to treat hypothyroidism, a condition where the thyroid gland does not produce enough hormones. This medication helps to maintain normal physiological functions by replacing the missing thyroid hormone . However, like many medications, levothyroxine can have side effects, including hair loss.

Hair Loss Due to Levothyroxine Overdose

Anagen Effluvium and Levothyroxine

Hair loss associated with levothyroxine can occur due to an overdose of the medication. Anagen effluvium, a type of hair loss that happens within days to weeks of starting a medication, has been observed in patients who receive high doses of levothyroxine. For instance, a case study of a 10-month-old infant with hypothyroidism showed that an overdose of levothyroxine led to sudden, diffuse scalp hair loss. The hair loss was reversed after the levothyroxine dose was reduced, indicating that the overdose was the cause .

Mechanism of Hair Loss in Thyroid Disorders

Both hyperthyroidism and hypothyroidism can lead to hair loss, although the mechanisms may differ. In hypothyroidism, hair tends to become dry, coarse, and brittle, with an increased proportion of hair in the telogen (resting) phase. Conversely, hyperthyroidism can cause hair to become fine, soft, and greasy, with reduced tensile strength and thinned hair shafts despite increased hair matrix proliferation . The presence of thyroid receptors in hair follicles suggests that thyroid hormones directly affect hair growth .

General Side Effects of Levothyroxine

Levothyroxine, while essential for managing hypothyroidism, can have several side effects, including hair loss. Other side effects may include joint pain, muscle cramps, and weight changes . These side effects highlight the importance of monitoring and adjusting the dosage of levothyroxine to avoid adverse effects.

Conclusion

Hair loss can be a significant side effect of levothyroxine, particularly when the dosage is too high. Both hypo- and hyperthyroid states can lead to hair loss, although the characteristics of the hair loss may differ. Proper monitoring and dosage adjustments are crucial to managing these side effects and ensuring optimal treatment outcomes for patients on levothyroxine.

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Most relevant research papers on this topic

Diffuse scalp hair loss due to levothyroxine overdose

Levothyroxine overdose can cause diffuse scalp hair loss in infants, but reducing the dose can lead to normal hair growth and no further hair loss.

Case Report

2015·

6citations

·K. Kumar et al.

Levothyroxine and Non-alcoholic Fatty Liver Disease: A Mini Review.

Levothyroxine may help mobilize hepatic fat and potentially mitigate Non-Alcoholic Fatty Liver Disease (NAFLD) in individuals with underactive thyroid conditions.

2023·

2citations

·P. Singha et al.

Tyrosine kinase inhibitors causing hypothyroidism in a patient on levothyroxine.

Tyrosine kinase inhibitors can cause hypothyroidism in patients on levothyroxine, leading to fatigue, brittle nails, and oedema.

Case ReportRigorous Journal

2006·

50citations

·J. D. Groot et al.

The impact of levothyroxine on thyroid autoimmunity and hypothalamic-pituitary-thyroid axis activity in men with autoimmune hypothyroidism and early-onset androgenetic alopecia.

Levothyroxine therapy benefits men with autoimmune hypothyroidism less pronouncedly in those with early-onset androgenetic alopecia.

Non-RCT

2021·

3citations

·R. Krysiak et al.

Medications and Food Interfering with the Bioavailability of Levothyroxine: A Systematic Review

Many medications and foods can impair the bioavailability of levothyroxine, requiring awareness and dose adjustment for optimal treatment.

Systematic Review

2023·

6citations

·Hanqing Liu et al.

Oral levothyroxine therapy postbariatric surgery: Biopharmaceutical aspects and clinical effects.

Bariatric surgery may compromise levothyroxine absorption or decrease dose requirements, requiring close monitoring of thyroid hormone levels.

Systematic Review

2019·

29citations

·Carmil Azran et al.

Levothyroxine Interactions with Food and Dietary Supplements–A Systematic Review

Levothyroxine ingestion in the morning and at bedtime is equally effective, but interactions with coffee, soy products, fiber, calcium, or iron supplements can decrease its absorption.

Systematic Review

2021·

37citations

·A. Wiesner et al.

Metabolic effects of liothyronine therapy in hypothyroidism: a randomized, double-blind, crossover trial of liothyronine versus levothyroxine.

Substituting L-T(3) for L-T(4) at equivalent doses in hypothyroid patients led to significant weight loss and improved lipid metabolism without affecting cardiovascular function or insulin sensitivity.

RCTVery Rigorous JournalHighly Cited

2011·

112citations

·F. Celi et al.

Effect of levothyroxine supplementation on pregnancy loss and preterm birth in women with subclinical hypothyroidism and thyroid autoimmunity: a systematic review and meta-analysis

Levothyroxine supplementation significantly decreases pregnancy loss and preterm birth risks in women with subclinical hypothyroidism and thyroid autoimmunity.

Meta-AnalysisVery Rigorous JournalHighly Cited

2019·

93citations

·M. Rao et al.

Levothyroxine initiation and the risk of pregnancy loss among pregnant women with subclinical hypothyroidism: An observational study emulating a target trial.

Initiation of levothyroxine during pregnancy is associated with a lower risk of pregnancy loss in women with subclinical hypothyroidism.

Observational Study

2023·

3citations

·S. Grandi et al.

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