The influence of hormones on hair loss. Which hormones should you have tested?

The influence of hormones on hair loss is a key issue in trichological diagnostics. The endocrine system directly regulates the life cycle of hair follicles. Any hormonal imbalance—whether involving the thyroid, adrenal glands, or the reproductive axis—can severely disrupt this equilibrium, shortening the growth phase (anagen) and leading to excessive hair loss.

The influence of hormones on hair – mechanisms of action

The primary factor driving the miniaturization of hair follicles is a group of hormones known as androgens—most notably testosterone and its more potent metabolite, dihydrotestosteron (DHT). While commonly associated with male-pattern baldness, an excess of—or hypersensitivity of receptors to—androgens also affects women, leading to what is known as female-pattern hair thinning. During menopause, a sharp decline in estrogen levels—which naturally serve to protect hair follicles—further exacerbates this issue.

Progesterone also has an adverse effect on the condition of hair. Fluctuations in its levels, as well as an imbalance in its ratio to estrogens, can stimulate the sebaceous glands to become overactive, which leads to an oily scalp. Meanwhile, elevated prolactin levels disrupt hormonal balance, exacerbating the processes that cause telogen effluvium (telogen hair loss).

In women, hormonal imbalances of a hyperandrogenic nature may be accompanied by symptoms of hirsutism—the appearance of excessive, male-pattern hair growth in areas such as the face, abdomen, or chest.

Which hormones should be tested in cases of hair loss?

If you notice chronic or excessive hair loss, it is crucial to consult a specialist. A doctor will provide a diagnosis and identify the root cause of the problem. It is helpful to know which laboratory tests can facilitate this process and expedite the implementation of targeted treatment. A basic diagnostic panel includes markers that assess the endocrine system, such as TSH, FT3, FT4, prolactin, total and free testosterone, androstenedione, progesterone, cortisol, and estradiol. Since the etiology of hair loss and thinning can be multifactorial, a holistic approach is essential.

Hair loss can also be caused by factors not directly related to the endocrine system. During the diagnostic process, it is crucial to assess general systemic parameters. A physician may order tests for ferritin levels (which reflect the body’s iron stores), vitamin B12, and glucose, as well as an insulin tolerance test, a complete blood count (CBC), and markers of inflammation (such as the erythrocyte sedimentation rate, or ESR). During the consultation, the specialist will conduct a detailed clinical interview and, if necessary, refer the patient for further specialized consultations—for example, with an endocrinologist or a gynecologist.

Here is a summary of key hormones, their approximate laboratory reference ranges, and their impact on the condition of hair follicles:

Women: 2–29 ng/mL
Men: 2–18 ng/mL

Morning level: 6–23 μg/dL
Evening level: 2–12 μg/dL

*Test results should always be interpreted in relation to the reference ranges of the laboratory where they were performed.

It should be emphasized that endocrine disorders represent only one of the potential causes of hair loss. In cases involving excessive hair shedding, professional medical diagnosis is always essential, as it enables the implementation of a safe and effective treatment.

Hair Loss and Thyroid Hormones

One of the most common systemic symptoms of thyroid dysfunction is the weakening and excessive shedding of hair. Both hypothyroidism and hyperthyroidism severely disrupt the body’s overall metabolic balance, which directly affects the condition of the scalp and hair follicles. Proper levels of thyroid hormones (T3 and T4) are essential for regulating the energy and nutritional processes within the cells of the hair matrix. Although these two conditions present with different clinical features, both result in a disruption of the hair growth cycle.

Abnormal levels of thyroid hormones lead to the premature termination of the anagen (growth) phase and the mass transition of hair follicles into the telogen (resting) phase. Furthermore, the function of the sebaceous glands is disrupted, causing the hair to become dry, dull, rough to the touch, and prone to breakage. Importantly, due to the physiological life cycle of hair, increased shedding typically occurs with a delay—approximately 2–4 months after the onset of hormonal imbalances in the body. Effectively halting this process requires the implementation of targeted pharmacological treatment under the supervision of an endocrinologist, as well as the restoration of full metabolic balance.

Cortisol and Hair Loss

Cortisol, produced by the adrenal cortex, is commonly referred to as the “stress hormone.” Its primary function is to prepare the body for a “fight-or-flight” response; however, prolonged, chronic elevation of its concentration in the blood serum leads to a range of adverse changes in tissue metabolism. One of the clinical manifestations of high cortisol levels is the weakening of hair follicles and excessive hair loss.

This mechanism stems from the negative impact of cortisol on blood circulation in the scalp and the oxygen supply to hair follicles. Chronic stress causes blood vessels to constrict, which leads to the undernourishment of cells in the hair matrix and their premature transition into a resting phase. The causes of excessive cortisol production can vary—ranging from prolonged psychological and physical strain and the use of certain medications (such as glucocorticosteroids) to endogenous hormonal disorders, such as tumors of the pituitary or adrenal glands.

Diagnostics in this area often involve measuring cortisol levels in blood serum, saliva, or a 24-hour urine collection, which allows for a precise assessment of the hormone’s circadian secretion rhythm. The therapeutic approach depends entirely on the diagnosed cause; effectively normalizing cortisol levels and eliminating stressors facilitates gradual hair regeneration and the restoration of a healthy hair growth cycle.

Hormonal treatment and specialized therapy for hair loss

The therapeutic strategy for hormonally-driven hair loss is always based on a precise clinical diagnosis. The key to success lies in a multifaceted approach that combines addressing the underlying cause with advanced aesthetic medicine and trichology.

The primary approach typically involves targeted hormone therapy, managed by an endocrinologist or gynecologist, aimed at restoring homeostasis within the body. As an adjunct to this general treatment, protocols are employed that include supplementation with substances essential for proper keratinization—such as vitamins and active ingredients with proven biological effects—are used. It should be noted that while at-home skincare and haircare products are important for the condition of the hair shaft, they serve only as a supplement to professional medical procedures.

At PT CLINIC, as part of our trichological services, we implement methods with high, proven efficacy:

• Scalp needle mesotherapy: the precise injection of nourishing cocktails, peptides, or platelet-rich plasma (PRP) to stimulate repair processes directly within the hair matrix.
• Trichoscopic diagnostics: enabling the monitoring of treatment progress and an objective assessment of hair follicle density.
• Advanced regenerative treatments: stimulating microcirculation and encouraging dormant hair follicles to grow.

In cases of advanced hair loss, where irreversible miniaturization of the hair follicles has occurred, we consider restorative surgical solutions, including hair transplantation. The expertise of a specialist, combined with a personalized treatment plan, ensures predictable, aesthetic results and long-term hair density.