Are patients with Lichen Planopilaris at Risk for Thyroid Disease?

Meta-analysis suggests two fold increased risks of thyroid disease in patients with lichen planopilaris.

Lichen planopilaris (LPP) is a type of immune mediated scarring hair loss condition. Several previous studies have examined whether patients with LPP are at increased risk to develop thyroid disease compared to people who don’t have LPP.

Studies in the past have shown a variety of results. Some studies in the past have suggested that patients with LPP are at increased risk to develop hypothyroidism. Other studies have suggested there is really not much of an increased risk. One study even suggested a trend towards a reduced risk.

Joshi et al 2023

Authors of a new study set out analyze the association between LPP and hypothyroidism by performing a systematic review of all the published medical literature followed by a meta-analysis. This means the authors carefully review all prior studies and didn’t leave any relevant ones out.

The authors searched medical databases (EMBASE and MEDLINE) using the keywords “comorbidities,” “hypothyroidism,” “lichen planopilaris,” and “thyroid.” They included in their study all the case–control studies that examined the prevalence of LPP among cases and controls.

There were 7 studies that the authors uncovered. The authors found 4 studies that reported a positive, statistically significant associations between LPP and hypothyroidism. There were 2 studies showing a  positive but statistically insignificant association and one study showed a negative, statistically insignificant association.

Overall, the meta-analysis showed an increased an approximately two fold prevalence of hypothyroidism in LPP patients compared with controls (OR = 1.75, 95% CI: 1.46–2.21, P = 0.001).

Conclusions

Patients with lichen planopilaris seem to be at increased risk to develop hypothroidism. This study reminds us all of the importance of testing thyroid levels in patients with LPP.

The reasons for the association are not clear and the study did not set out to search for a reason. It could be that patients with hypothyroidism and LPP share some sort of dysregulation of T cell or cytokine pathways.

We don’t know if the risk is going to be different in patients with more severe LPP than patients with less severe LPP or whether patients with different subtypes of LPP have different risk. For example, we don’t know if patients with the frontal fibrosing alopecia (FFA) type of LPP have different risk than classic LPP.  

Overall, this was a nice study highlighting the increased risk of thyroid disease that is present in patients with LPP.

References

Joshi TP et al. Association of lichen planopilaris with hypothyroidism: a systematic review and meta-analysis. Int J Dermatol. 2023 Jul 10.23 Nov;62(11):e606-e608.