The Quantification of Terminal Hair by Digital Microscopy: Advancements Towards a More Objective Diagnosis of Hirsutism

Purpose: The modified Ferriman-Gallwey score, currently used to clinically evaluate and quantify excessive hair growth in women with hirsutism, has limitations because of its subjective nature. Therefore, we aim to investigate whether we could quantify terminal hairs on the output of a digital microscope camera to improve the clinical evaluation of hirsutism. Patients and Methods: This feasibility cross-sectional study included 20 healthy men and 15 healthy women. Two independent researchers used a digital microscope camera to obtain photos of the upper lip and chin in all participants. The hair thickness (when ≥ 60 µm), number of terminal hairs and hair color were determined to indicate mean differences between men and women by an independent t-test. Additionally, intraclass correlation coefficients were determined to assess the inter-observer variability. Results: The mean (standard deviation) number of terminal hairs on the upper lip was 27 (15) in men and 0 (1) in women. On the chin, men had a mean (standard deviation) of 29 (18) terminal hairs, compared to 0 (0) in women. This corresponds to mean differences of 27 hairs (range: 19–34) on the upper lip and 28 hairs (range: 19–39) on the chin between men and women. Minimal inter-observer variability was observed, particularly in visible light analyses (intraclass correlation coefficient: 0.998). Conclusion: Digital microscopy with visible light may contribute to a more objective method for diagnosing hirsutism by the quantification of terminal hair. Future studies should focus on the applicability of this new method in women with hirsutism.