alopecia and hair covering

this is a hypothetical question posed to me by a non jewish friend and i quite honestly don’t know the answer. FOR raised reform but now becoming more religious. if a woman (let’s say orthodox for this example) has alopecia, once she gets married would she still be obligated to wear a head covering? my understanding is that it is the HAIR that is being covered, not the skin of the head. any comments on this? i know this would warrant asking a personal rabbi but this is purely for my own edification.