ANSWER
This is a classic clinical picture of androgenetic alopecia (choice “a”). See discussion for more details.
Alopecia areata (choice “b”) usually manifests acutely and leads to complete hair loss in a well-defined, annular pattern. It typically resolves on its own, with or without treatment.
Telogen effluvium (choice “c”) involves generalized hair loss without a pattern. The hair is actually “lost,” meaning markedly increased amounts of hair are seen in the comb, brush, sink, or shower. This results in an increasingly visible scalp.
Without a clear clinical picture of alopecia, a biopsy might have been indicated—primarily to rule out conditions such as lupus erythematosus (choice “d”), which can involve hair loss of various kinds. The negative ANA result obtained by the patient’s primary care provider helped rule out this diagnosis.
DISCUSSION
Androgenetic alopecia (AGA) affects both men and women, though the latter begin to develop it about 10 years later, on average, than men do. Among women, 13% develop AGA before menopause, while 75% note its appearance postmenopausally.
In both sexes, AGA results from the gradual conversion of terminal hairs to vellus hairs, with miniaturization of the follicles. Hair loss in men starts in the vertex, followed by bitemporal recession. In women, AGA primarily affects the crown of the scalp, often with partial preservation of the frontal hairline.
Dihydrotestosterone (DHT) appears to be the main culprit; testosterone is converted to DHT by means of the enzyme 5α-reductase. One of the most effective medications for AGA in men has been finasteride, which blocks the effects of 5α-reductase and can at least slow the rate of hair loss. Unfortunately, finasteride does not appear to be effective in treating AGA in women.
Women do, however, appear to respond to minoxidil, a topically applied solution, better than men. The response is moderate at best, and any hair gained is lost if the treatment is discontinued. Interestingly, the stronger 5% solution of minoxidil in women does not produce any demonstrable improvement over that seen with the 2% solution.
From a practical diagnostic standpoint, it is quite common for women with longstanding mild to moderate AGA to present with an acute episode of telogen effluvium (TE), in which hair all over the scalp falls out. Careful history taking is necessary to tease these stories apart, since TE will typically resolve on its own. The most common causes of TE, in my experience, are stress, extreme weight loss, and as a consequence of general anesthesia. For unknown reasons, TE is almost nonexistent in men.
TREATMENT
This patient chose to use 5% OTC minoxidil, an antihypertensive with an unknown mode of action in AGA. She’ll confine its application to the affected areas of the scalp, since unwanted hair growth has been reported on the face with the use of this medication.