Hair Thinning & Loss

Understanding Hair Thinning and Loss

Hair thinning and loss are among the most common reasons people seek medical evaluation, affecting both men and women across a wide range of ages. While losing roughly 50 to 100 hairs per day is normal, a noticeable decline in density, a widening part, a receding hairline, or visible patches of loss can signal an underlying issue that deserves attention. Because hair growth reflects the health of the whole body, changes in your hair are sometimes the first visible sign of a hormonal, nutritional, or metabolic imbalance.

At ENNU Life in Louisville, Kentucky, we evaluate hair concerns as part of a broader picture of your hormonal and metabolic health rather than treating them in isolation.

How Hair Growth Works

Each hair follicle cycles through three main phases: anagen (active growth, lasting years), catagen (a brief transition), and telogen (rest and shedding). At any given time most follicles are in the growth phase. Many forms of hair loss occur when this cycle is disrupted, pushing more follicles into the resting and shedding phases or shortening the growth phase so that hairs become progressively finer over successive cycles.

Common Causes of Hair Thinning and Loss

Hair loss is not a single condition but a symptom with many possible drivers. Common, well-established causes include:

• Androgenetic alopecia (male- and female-pattern hair loss): a genetically influenced sensitivity of follicles to androgens, producing gradual miniaturization of hair, typically at the crown, temples, or along the part line.
• Telogen effluvium: diffuse shedding triggered by a physiologic stressor such as illness, surgery, significant weight loss, childbirth, or emotional stress, usually appearing two to three months after the trigger.
• Thyroid disorders: both underactive (hypothyroid) and overactive (hyperthyroid) states can cause diffuse thinning.
• Nutritional deficiencies: low iron stores, vitamin D, zinc, or inadequate protein intake can impair hair growth.
• Hormonal changes: shifts in estrogen, progesterone, testosterone, or DHT, including those around menopause or with conditions such as polycystic ovary syndrome.
• Autoimmune conditions such as alopecia areata, which causes well-defined patches of loss.
• Medications and medical treatments, certain scalp conditions, and tight hairstyling practices.

Relevant Lab Markers

Because so many causes are internal, laboratory testing often guides effective treatment. A clinician may consider markers such as a complete blood count, ferritin (iron stores), thyroid panel (including TSH and free thyroid hormones), vitamin D, and, when appropriate, sex hormones such as testosterone, DHEA-S, and others. Reference ranges are assay-dependent and vary between laboratories, so results should always be interpreted by a clinician in the context of your symptoms and history rather than compared against a single fixed number.

When to Seek Evaluation

Consider a professional evaluation if you notice any of the following:

• Sudden, rapid, or patchy hair loss
• A widening part, thinning crown, or receding hairline
• Shedding accompanied by fatigue, weight changes, cold or heat intolerance, or menstrual changes
• Scalp redness, scaling, itching, pain, or scarring
• Hair loss that is causing significant distress

Scarring forms of hair loss, in particular, are best evaluated early because follicles that are permanently damaged cannot regrow.

How Hair Loss Is Approached Clinically

A thorough evaluation typically begins with a detailed history and scalp examination, followed by targeted laboratory testing to identify reversible contributors. Treatment depends entirely on the cause. Correcting a thyroid imbalance, replenishing iron or vitamin D, addressing a hormonal shift, or allowing a telogen effluvium to resolve can each restore healthier growth. For pattern hair loss, clinicians may discuss established medical therapies and realistic expectations about slowing progression and improving density over time. Because hair grows slowly, meaningful results generally require several months of consistent care.

Take the Next Step

Hair thinning is often a window into your overall hormonal and metabolic health. A structured assessment is the most reliable way to understand what is driving your symptoms and what can be done about it.

Start your ENNU Life Health Assessment

Educational only, not medical advice; consult a licensed clinician.