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androgenic alopecia; androgenetic alopecia; male balding pattern

also see alopecia &/or pattern alopecia Epidemiology: - most common cause of alopecia in men - 50% of men at age 50 years; 70% at age 70 years [6] - can effect men or women Pathology: - dihydrotestosterone promotes involution of hair follicles in genetically-prone men - non-scarring alopecia [6] Genetics: - generally inherited trait - autosomal dominant with mixed penetrance - homozygous mutations of WNT10A cause recessive odonto-onycho dysplasia & sparse scalp & body hair [4] (WNT signaling occurs normally in hair development & hair cycling) Clinical manifestations: - men - receding hairline - baldness on the top of the head - gradual thinning in the temporal areas - the hair loss in an area is not complete - women - hair generally is lost diffusely over the crown resulting in a gradual thinning of the hair, widest anteriorly - a widening of the central part may be noted - the hair loss in an area is not complete - the frontal hairline is often preserved in women - bitemporal recession to a lesser degree than in men * images [9,10] Differential diagnosis: - alopecia areata is generally associated with an area of marked baldness [6] - telogen effluvium is trigerred by a stressful event - commonly seen in post-partum women [6] Complications: - cardiovascular risk factor [3], especially, baldness at the crown of the head [3] Management: 1) men a) some men elect to forgo treatment b) topical minoxidil 5% BID - best results with patients < 30 with < 5 years hair loss c) oral finasteride or dustateride 2) women - topical minoxidil 2% (Rogaine) BID - spironolactone [6] 4) surgical procedures a) hair transplant b) scalp reduction c) flaps

General

pattern alopecia

References

  1. Hair Loss and Its Causes FamilyDoctor.org http://familydoctor.org/online/famdocen/home/men/general/081.html
  2. Wikipedia: Baldness http://en.wikipedia.org/wiki/Baldness
  3. Tomohide Yamada, Kazuo Hara, Hitomi Umematsu, Takashi Kadowaki Male pattern baldness and its association with coronary heart disease: a meta-analysis. BMJ Open 2013;3:e002537 PMID: 23554099 http://bmjopen.bmj.com/content/3/4/e002537
  4. Heilmann S et al. Androgenetic alopecia: Identification of four genetic risk loci and evidence for the contribution of WNT signaling to its etiology. J Invest Dermatol 2013 Jun; 133:1489. PMID: 23358095
  5. Rathnayake D, Sinclair R. Male androgenetic alopecia. Expert Opin Pharmacother. 2010 Jun;11(8):1295-304 PMID: 20426708
  6. Medical Knowledge Self Assessment Program (MKSAP) 17, 18. American College of Physicians, Philadelphia 2015, 2018.
  7. Genetics Home Reference: Androgenetic alopecia http://ghr.nlm.nih.gov/condition/androgenetic-alopecia
  8. Feinstein RP, Khardori R Medscape: Androgenetic Alopecia http://emedicine.medscape.com/article/1070167-overview
  9. DermNet NZ. Female pattern hair loss (images) http://www.dermnetnz.org/hair-nails-sweat/female-pattern-hairloss.html
  10. DermNet NZ. Male pattern hair loss (images) http://www.dermnetnz.org/hair-nails-sweat/pattern-balding.html
  11. Gupta AK, Venkataraman M, Talukder M et al Relative Efficacy of Minoxidil and the 5-alpha Reductase Inhibitors in Androgenetic Alopecia Treatment of Male Patients. A Network Meta-analysis. JAMA Dermatol. Published online February 2, 2022. PMID: 35107565 https://jamanetwork.com/journals/jamadermatology/fullarticle/2788258 - Huang KP, Senna MM. Hair Are the Rankings - 5-alpha Reductase Inhibitors and Minoxidil in Male Androgenetic Alopecia. JAMA Dermatol. Published online February 2, 2022 PMID: 35107586 https://jamanetwork.com/journals/jamadermatology/fullarticle/2788261