what is the normal eyebrow hair loss per day? what does alopecia areata look like in the eyebrow area? is it a sudden hair loss?
The eyebrow telogen cycle lasts about 9 months, so for hairs that fall out, it would take up to 9 months for them to return. I suspect that the growth phase is also shorter than scalp hair, possibly 3-6 months, which means that the growth of eyebrow hair occurs in short periods of time. We see the same with body and leg hair (long telogen cycles and short growth cycles). For more about hair cycles, see here.
The appearance of alopecia areata may occur in spotty areas or parts of the eyebrow. A biopsy of the edge of such spots of balding is the way to make the diagnosis. These patchy areas often start small and then enlarge.