Hereditary hair thinning and balding occurs in genetically susceptible healthy men as well as women and starts at puberty. It is such a gradual process that it may go unnoticed for years. Men lose hair in specific patterns, but women tend to retain their hairline and thin diffusely behind the hairline. The process also starts at puberty in healthy women as it does in men.
Bloodwork for hormones and thyroid are totally normal in both men and women and they are healthy.
In all individuals (men and women) each hair follicle is on a different growth cycle (and there are tens of thousands of follicles) so that all individuals shed approximately 100 hairs daily. The diagnosis of hereditary thinning/balding is not made by the number of hairs shed, as even non-balding individuals shed 100 ± hairs daily. The diagnosis is made by noting the pattern of hair loss and thinning.
Treatments are very effective and financially reasonable in compliant individuals but must be maintained for a lifetime (or until gene therapy is perfected!)