Androgens play a pivotal role in the growth of pubic and axillary hair. Androgens stimulate growth of beard hair, whereas in the scalp, androgens inhibit hair regrowth. Clinical studies by James B. Hamilton in the early 1940's suggested that the balding process is promoted by androgens in genetically predisposed men, referred to as androgenetic alopecia or male pattern hair loss. The androgen acting in the scalp to promote the balding process was not known at the time. It was not until the 1960's when it was discovered that testosterone is converted to the more bioactive androgen dihydrotestosterone by the microsomal, NADPH-dependent enzyme steroid 5alpha-reductase in peripheral androgen-responsive tissues such as the prostate and skin [4]. Two genes encoding two isoenzymes of steroid 5alpha-reductase exist, designated type 1 and type 2 [5, 6]. The type 1 isoenzyme is the major 5alpha-reductase in skin, has a neutral pH optimum and a low affinity for testosterone. Steroid 5alpha-reductase type 2, on the other hand, is the major isoenzyme in the prostate, has an acidic pH optimum and a high affinity for testosterone. The notion that DHT, and not testosterone, is the androgen responsible for benign prostate hyperplasia and male pattern hair loss stems from the observation that men with steroid 5-alpha-reductase 2 deficiency present with a hypoplastic prostate and do not develop male pattern baldness . Consequently, the 5 alpha-reductase type 2 isoenzyme-specific inhibitor finasteride has proven efficacious in promoting hair regrowth as a consequence of lowering scalp and plasma DHT levels, and in the treatment of benign prostate hyperplasia by lowering prostatic DHT.
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JAMA Dermatol. 2013 May 22:1-5. doi: 10.1001/jamadermatol.2013.3049. [Epub ahead of print]
Autoimmune, Atopic, and Mental Health Comorbid Conditions Associated With Alopecia Areata in the United States.
Huang KP, Mullangi S, Guo Y, Qureshi AA.
Abstract
OBJECTIVE To evaluate the prevalence of comorbid conditions among patients with alopecia areata (AA) seen at tertiary care hospitals in Boston, Massachusetts, during an 11-year period. DESIGN Retrospective cross-sectional study. SETTING Tertiary care hospitals in Boston, including Brigham and Women's Hospital and Massachusetts General Hospital. PARTICIPANTS We identified 3568 individuals with AA seen in the Partners health care system in Boston between January 1, 2000, and January 1, 2011. We performed comprehensive searches of the Research Patient Data Repository using International Classification of Diseases, Ninth Revision code 704.01. We randomly selected 350 patients and manually reviewed their medical records to train and validate a novel artificial intelligence program. This program then used natural language processing to review free-text medical records and confirm a diagnosis of AA. To confirm the algorithm, we manually reviewed a subset of records and found 93.9% validity. MAIN OUTCOMES AND MEASURES The prevalence of comorbid conditions was assessed. RESULTS Common comorbid conditions included autoimmune diagnoses (thyroid disease in 14.6%, diabetes mellitus in 11.1%, inflammatory bowel disease in 6.3%, systemic lupus erythematosus in 4.3%, rheumatoid arthritis in 3.9%, and psoriasis and psoriatic arthritis in 2.0%), atopy (allergic rhinitis, asthma, and/or eczema in 38.2% and contact dermatitis and other eczema in 35.9%), and mental health problems (depression or anxiety in 25.5%). We also found high prevalences of hyperlipidemia (24.5%), hypertension (21.9%), and gastroesophageal reflux disease (17.3%). This profile was different from that seen in a comparison psoriasis and psoriatic arthritis group. CONCLUSIONS AND RELEVANCE We found a high prevalence of comorbid conditions among individuals with AA presenting to academic medical centers in Boston. Physicians caring for patients with AA should consider screening for comorbid conditions.
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Adv Nurse Pract. 1999 Apr;7(4):39-42, 83. Hair-raising. The latest news on male-pattern baldness.
Proctor PH.
The initiating event in balding seems to be an abnormal sensitivity to the male sex hormones. In addition, a multifactorial model is emerging in which hormones affect the hair follicle in a way that causes it to be perceived as a foreign body by the immune system, which then mounts an attack. Several new classes of agents have the potential to treat hair loss. More than 40 U.S. and several hundred foreign patents have been issued for hair-loss treatment agents. As is common in dermatology, no single agent works universally against hair loss, so the treatment process is often one of trial and error.
This is a paper by Dr. Proctor