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Glossary2D:4D ratio (digit ratio)

relative length of index to ring finger

The 2D:4D ratio, also known as the digit ratio, refers to the comparative length of the second digit (index finger) to the fourth digit (ring finger). This ratio is often used as a biomarker for prenatal hormone exposure, with a lower ratio (shorter index finger relative to the ring finger) typically indicating higher exposure to testosterone, and a higher ratio indicating higher exposure to estrogen. This measure has been linked to various biological and behavioral traits, including susceptibility to certain diseases and conditions.

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research Second-To-Fourth Digit Ratio and Age Predicting the Severity of Androgenetic Alopecia: A Cross-Sectional Study

December 2022 in “The Aging Male”

Lower 2D:4D ratio and older age increase the risk of severe hair loss in men.

research An Isolated, Implausibly Large Effect in a Case-Control Study of Digit Ratio (2D:4D) and Male Androgenetic Alopecia: Comment on Unal

February 2021

Digit ratio likely doesn't predict male hair loss.

research Can the Second to Fourth Digit Ratio (2D:4D) Be a Marker to Determine Ankylosing Spondylitis Disease Activity?

3 citations, February 2019 in “Disease Markers”

The index to ring finger ratio may indicate disease severity in female ankylosing spondylitis patients, but not in males.

research The Relationship of the 2nd:4th Digit Ratio to the Maxillary Sinus Volume in Men

June 2018 in “Biomedical Journal of Scientific and Technical Research”

Men with lower 2nd to 4th finger ratios tend to have larger sinus volumes.

research Deep Hair Phenomics: Implications in Endocrinology, Development, and Aging

September 2024 in “Journal of Investigative Dermatology”

A new tool can analyze hair to detect changes due to hormones, genetics, and aging.

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community 4600 - result 9 month - Dr. Carman

Felix8020 in Progress Pictures 253 upvotes 1 year ago

A user shared their 9-month post-hair transplant results with 4600 grafts, using only Nourkin hair vitamins, Vitamin D, and B12, and expressed satisfaction. The replies debated the necessity of medications like finasteride and minoxidil for maintaining hair health.

community Why I deleted my YouTube channel Part I

Rider_Of_Roach in Update 118 upvotes 3 years ago

A YouTuber named Kevin, also known as Rider_Of_Roach, who deleted his YouTube channel due to personal attacks and controversy surrounding his views on hair loss treatments. He advocated for FDA-approved treatments like finasteride and minoxidil but faced backlash from those who disagreed with him. The conversation also discusses his past trolling behavior and a lawsuit he filed against a website that published false information about him. Despite some disagreements, many viewers appreciated his research-based content and hope to see him return in the future.

community Physician here AMA – 30M oral Fin 1-1.25 mg daily

BanksCarlton in Update 47 upvotes 2 years ago

Hair loss treatments, specifically the use of finasteride, microneedling and potentially oral minoxidil. People discussed their experiences with finasteride, its effects on sexual behaviors, as well as potential solutions such as tadalafil or using other growth factor signal peptides for hope in curing male pattern baldness.

community People treat me so different when I was bald compared to my comb over.

TheSeabass_999 in Chat 226 upvotes 4 months ago

The user feels treated better with a comb-over than when bald due to cancer. They are considering a hair transplant and using finasteride and minoxidil for hair loss.

community Have you ever seen a "back from the dead" result that DIDNT use microneedling?

cretinouswords in Microneedling 33 upvotes 3 months ago

Some users report significant hair regrowth without microneedling, using treatments like finasteride, minoxidil, and dutasteride. Others believe microneedling enhances results, but opinions vary on its necessity.

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