The hair pull test is the oldest quick check in hair loss: take a small section, draw your fingers through it, and count what comes away. The number that separates normal from concerning had been carried forward for decades without anyone measuring it in a modern group of people. A team in Canada set out to do exactly that. They performed a single standardized pull on 181 people and counted what came out, then compared the results against when each person had last washed and brushed their hair, their hair texture, their medications and the styles they wore.

The average number of hairs that came away was 0.44, which is to say usually none or one. Ninety-seven percent of people gave up two hairs or fewer, and the authors proposed that two should be the new upper limit of normal rather than the higher figure in circulation. Washing made no significant difference to the count, and neither did brushing, which led them to recommend relaxing the old rule about not washing for five days before the test. Hair texture made no significant difference across the groups they compared, and neither did tight hairstyles or medications affecting hair. Some limits on that. Everyone tested was a healthy volunteer with no hair loss, so the study establishes what normal looks like without showing how well the test identifies people who are actually shedding. It was one pull per person at one center, and the washing and brushing details were self-reported. The authors name that last point as their own limitation.

Here's the study: McDonald KA, Shelley AJ, Colantonio S, Beecker J. Hair pull test: Evidence-based update and revision of guidelines. Journal of the American Academy of Dermatology, 2017;76(3):472-477. Read it here

Ready to go deeper? The Bridge takes that vocabulary and gives you true trichology education. This is where the real depth lives, working with me to understand what you're seeing and why it's happening.

It's the education you build a practice on.

Go deeper with the Bridge