Hormonal IUDs might be associated with lower rates of non-scarring hair loss in patients compared with copper IUD placement, US researchers have found.

Their analysis published in a brief report for the Journal of the American Academy of Dermatology [link here] evaluated alopecia development following low-dose hIUD, high-dose hIUD and cIUD placement to shed light on conflicting evidence.

They tracked the outcomes of 57,674 patients divided into hIUD versus cIUD groups, and 41,652 patients divided by low and high dose over 2 years. Overall, 267 and 302 patients developed alopecia after hIUD and cIUD placement respectively.

Findings for hIUD versus cIUD placement:

• A reduced hazard for composite alopecia (HR 0.833, 95% CI 0.707-0.982, p=0.029)
• A reduced hazard for non-scarring alopecia (HR 0.791, 95% CI 0.665-0.941, p=0.008)
• An increased risk for cicatricial alopecia (HR 1.229, 95% CI 0.763-1.978, p=0.396)

Findings for low-dose versus high-dose hIUD placement:

• No difference for non-scarring alopecia (low-dose HR 1.060, 95% CI 0.829-1.355, p=0.640)
• No difference for scarring alopecia (HR 0.684, 95% CI 0.342-1.366, p=0.279)
• No difference for overall alopecia (HR 0.998, 95% CI 0.789-1.261, p=0.984)

The researchers said their findings added to the available evidence by evaluating hormonal dose as well as device type, and also raised the possibility of a non-hormonal cause for the reduced likelihood of alopecia development.

“We hypothesise that reduced menstruation with hIUD (compared to cIUD) and resulting improvements in iron stores, as reflected by higher ferritin levels in hIUD users, may contribute to lower rates of hair loss,” the researchers said.

However, they noted that the clinical significance of their main finding – composite alopecia in patients with hIUD versus cIUD placement – was unclear. They pointed to the small 0.002 absolute risk difference, corresponding with a number needed to treat of 500, and the p-value, which was near the significance threshold.