The “Bidirectional Relationship” Between Alopecia Areata and Thyroid Disease

We’ve discussed the concept of bidirectional relationships in prior articles of the Beyond the Scalp Blog. For review, be sure to check out the prior article, “Bidirectional Relationships in Hair Loss”

Common examples of these so-called “bidirectional relationships” include:

Alopecia Areata and the Risk of Depression

Alopecia Areata and Attention Deficit Hyperactivity Disorder

Alopecia Areata and Migraines

Androgenetic Alopecia and Sleep Disturbances

Frontal Fibrosing Alopecia and Rosacea

The Bidirectional Relationship Between Thyroid Disease and Alopecia Areata

Authors of a new study used a database to evaluate whether patients with alopecia areata or androgenetic alopecia were at increased risk for hypothyroidism and whether patients with hypothyroidism were at increased risk for alopecia areata or androgenetic alopecia. For studies in alopecia areata, 682 cases were compared to 361,140 controls. For studies in AGA, 195 cases were compared to 201,019 controls.

Interestingly, alopecia areata was associated with an increased risk of hypothyroidism (odds ratio [OR], 1.0017; 95% confidence interval [CI], 1.0004-1.0029; P = 0.0101). Additionally, hypothyroidism was found to be strongly correlated with an increase in the risk of alopecia areata (OR, 45.6839; 95% CI, 1.8446-1131.4271, P = 0.0196). However, no causal relationship was found between AGA and hypothyroidism.

Comment

This bidirectional relationship is important and enters into my clinical thinking almost daily. We all know that patients with alopecia areata have a greater chance of having hypothyroidism than an average person might have. What is not always appreciated is that patients with hypothyroidism are at increased risk for alopecia areata.

Another ‘bidirectional relationship’ to add to the list.

As an example, consider the 32-year-old woman with a complex clinical presentation. She has what appears to be diffuse, non-scarring alopecia, but nobody can’t quite figure out what’s going on with her hair loss. After reviewing her chart, you realize she has hypothyroidism. Of course, not everyone with hypothyroidism has alopecia areata but in this sort of a challenging case you must say to yourself… “Oh, I wonder if there’s any chance there is some autoimmune scalp disease going on, given this patient has hypothyroidism. Is it at all possible she has alopecia areata or scarring alopecia? Let me look again with my trichoscope, and if I still can’t solve the diagnosis, then I’ll consider a biopsy.”

The relationship between hypothyroidism and alopecia areata is interesting!

REFERENCES

Yang et al. Association between non-scarring alopecia and hypothyroidism: a bidirectional two-sample Mendelian randomization study Front Endocrinol (Lausanne). 2024 Mar 18:15:1356832. doi: 10.3389/fendo.2024.1356832. eCollection 2024.