Male Pattern Hair Loss: Understanding Androgenetic Alopecia

What Is Male Pattern Hair Loss?

A patient in his early thirties came in last year with photos he had been collecting on his phone for two years. Side by side, they told a clear story: the temples were creeping back, the crown was thinning at the vertex. He had not wanted to come in. He told me his dad had gone bald in his thirties and he figured this was just inevitable. He wanted to know if it was too late. It was not too late, and I told him so directly. What he had was androgenetic alopecia, the most common form of hair loss in men, affecting roughly half of all men by age 50. It is a genetically determined response to a hormone called DHT, a potent derivative of testosterone. The follicles were miniaturizing, not disappearing. And the earlier you address it, the more you have to work with. He left with a treatment plan that day.

Why Does It Happen?

When I sit down with male patients experiencing this kind of thinning, I explain it this way: your follicles at the hairline and crown are genetically sensitive to a hormone called dihydrotestosterone, or DHT. DHT is derived from testosterone via an enzyme called 5-alpha reductase. In follicles that carry this sensitivity, DHT shortens the growth phase of the hair cycle a little more with each successive cycle. The follicle does not die. It miniaturizes. Over time, the hairs it produces come back shorter, finer, and lighter until they become essentially invisible. The follicles at the back and sides of the scalp do not carry this same sensitivity, which is why they remain. This is a predictable pattern. And it is why timing matters. The earlier you intervene, the more follicles are still in an active, productive phase where they can respond to treatment. Waiting until there is visible bald scalp means you are working with follicles that are already significantly miniaturized, and the window to support meaningful density has narrowed considerably. One thing I always check before diagnosing androgenetic alopecia is whether there is a treatable contributing factor making things worse. Thyroid dysfunction, iron deficiency, and elevated prolactin can all accelerate hair loss in men and are frequently missed. The pattern of male pattern loss is distinctive, but ruling out reversible causes first means you are treating the right thing, with the right tools, from the start.

What It Looks Like

• Hairline recession beginning at the temples, often forming a characteristic M-shape in the early stages
• Thinning at the vertex (crown) that develops independently and gradually expands outward toward the temples
• Hairs in affected zones become progressively finer, shorter, and lighter before eventually stopping production
• The front and crown of the scalp are primarily affected while the sides and back remain dense and resistant
• Progression follows a predictable trajectory described by the Norwood scale, from mild recession to more extensive coverage
• The process is gradual and unfolds over years to decades, making it easy to underestimate how far it has progressed
• Increased scalp visibility under bright or overhead lighting is often the first thing patients notice in photos
• Sebum and scalp buildup can accumulate more readily in thinning areas, potentially compounding follicle stress