Upright regrowing hair vs miniaturized/vellus hair?

Width, length, presence of outer and inner root sheath and pigmentation should differentiate between the two. A white card test looking at the distal ends of the hair is also helpful. A horizontal 3 level biopsy will easily tell you the terminal /vellus ratio.PRP hair md.com

This is why patients will come to my office, so they can get the information they need.  Most cosmetic and hair consultations are complimentary.  I would have you see a qualified plastic surgeon, facial plastic surgeon or dermatologist who specializes in hair.  They will be able to offer you options as far as what treatments might be best for you - topicals, PRP (still not proven but may be beneficial) or surgical treatment like FUE (whether by SmartGraft, Neograft, or Artis).  Good luck.

Great question! The reality is it can sometimes be challenging especially when comparing miniaturization in AGA to a true URH in a pure telogen effluvium.So please see your dermatologist or physician familiar with scalp dermoscopy.
A true URH (terminal hair) is usually thicker caliber than a vellus hair in AGA. But the key to your question is this: if these short hairs are seen ALL OVER the scalp (top, front, left, right) AND in Equal proportions then it is likely an URH in a telogen effluvium. If these short hairs are found only in one main area (ie the area of hair loss), then the short hairs are more likely vellus or DHT affected hairs. This is how we distinguish by dermoscopy.