Ludwig and Sinclair scales (female pattern hair loss)
The Ludwig and Sinclair scales grade female pattern hair loss, which usually thins the crown while keeping the front hairline: Ludwig uses three grades and Sinclair uses five photographs of a centrally parted scalp.
Full definition
Female pattern hair loss usually looks different from the male pattern, so it has its own scales. In 1977 the dermatologist Erich Ludwig, writing in the British Journal of Dermatology after observing 468 women, described three grades. In Grade I there is noticeable thinning over the crown, starting 1 to 3 cm behind the front hairline. In Grade II that thinning is pronounced. In Grade III the hair over that area is lost entirely. Ludwig stressed that the front hairline is usually preserved even as the thinning spreads (Gupta and Mysore, 2016). The Sinclair scale, published in 2004, is a five-point photographic scale: five pictures of women's scalps parted down the middle, from a normal scalp (1) to increasingly severe thinning (2 to 5), so that patients and clinicians can pick the one that looks most like them and track it over time. Ludwig also noted that a minority of women lose hair in the male pattern, and those cases are described with the Hamilton-Norwood scale instead. In women, miniaturisation is usually less marked than in men, and the role of androgens is not yet clear (Bhat and colleagues, 2020). The NHS notes that minoxidil can be used for female pattern hair loss and that women should not use finasteride; see can women use minoxidil. Thinning in women has several possible causes, and blood tests such as a female hair loss blood test can help a doctor look for some of them, such as low iron.
What it does not mean
A grade on either scale describes how much thinning there is, not what is causing it, so it cannot replace a diagnosis. A low grade does not mean the hair loss is "not real" or not worth taking seriously, and a high grade does not tell you how you should feel about it. Nor does a female pattern of thinning prove a hormone problem: it occurs in some women with normal androgen levels.
UK regulatory source
No UK regulator defines these scales; they are clinical classifications. Ludwig E. Classification of the types of androgenetic alopecia (common baldness) occurring in the female sex. Br J Dermatol 1977 (PMID 921894); Gupta M, Mysore V. Classifications of patterned hair loss: a review. J Cutan Aesthet Surg 2016; Bhat YJ et al. Female pattern hair loss: an update. Indian Dermatol Online J 2020; NHS, Hair loss