Connection Between Hormones and Hair Loss

Posted by Ben White on heinäkuu 31, 2019

By Dr. Kate Placzek, ZRT Laboratory

A symbol of femininity for so many women, our hair demands attention. Both deeply personal and superficially public, changes in the appearance of our hair can inspire a range of emotions — driving us to willingly partake in its cutting, straightening, curling, bleaching, darkening, or other aggressive chemical treatments. Hair is part of who we are and how we present ourselves to the world. This is why thinning hair is kind of a big deal — it can be a very frustrating topic for many women, as there is no quick solution to getting more hair instantly.

Ironically, the phrase “beauty is only skin deep” is not entirely appropriate in conversations about hair. Thinning, dry hair is actually a symptom of internal changes in the body. Perhaps viewed by some as a normal, inevitable sign of ageing or a response to stress, losing hair is oftentimes related to endocrine imbalances. This blog reviews the role that hormones play in hair health.

How Hair Follicles Work

Hair Follicles Cycle Between Rest and Growth

Before we jump into endocrine logistics, let us review some anatomical considerations. Hair changes can occur due to alterations of the hair fibre itself, the hair cycle, and/or the hair follicle — the portion of hair beneath the surface of the skin. Hair follicles are incredibly productive, constantly undergoing cyclical rounds of rest (telogen), regeneration (anagen) and degeneration (catagen). They are unique in their ability to dynamically alternate between rest and active growth.

The Hormonal Causes of Hair Loss

Stress and Cortisol: The Stress–Tress Connection

We all know that stress is bad for you — including your hair. Bluntly speaking, stress makes your hair fall out. This is largely because stress puts you in survival mode, diverting resources away from good skin blood flow, adequate digestion, sleep and growth, so the energy can be used instead for fight or flight. Your body does not regard hair as essential to your survival.

Stress molecules like cortisol can target and damage the hair follicle [1]. You do not even have to wait until menopause for stress-induced hair thinning — many women in their 20s and 30s start losing hair due to stress-related issues [2]. Symptoms of sudden bouts of hair shedding with little to no hair growth are suggestive of telogen effluvium — a condition where hair in the anagen (growing) phase prematurely enters the telogen (resting) phase [3]. Furthermore, stress resulting from the hair loss itself aggravates and perpetuates the vicious cause-and-effect cycle.

To assess your stress burden at a biochemical level, our Diurnal Cortisol Test (4-Point Saliva) measures cortisol across four time points throughout the day, revealing whether your adrenal hormones are contributing to hair loss and fatigue.

Sex Hormones: Oestrogen, Progesterone and Testosterone

Pregnancy: Pregnancy increases the number of hair follicles in the anagen (growth) phase. The enhanced supply of estradiol and progesterone in pregnancy are particularly nurturing to hair, expanding the growth phase and preventing shedding. However, at about 3 months postpartum, when hormones re-equilibrate to a “new normal”, hair can come out in clumps. If hair loss is experienced in the postpartum period, most women will experience a full recovery, although the process may be slow.

Menopause: When the levels of estradiol and progesterone fall in menopause, hot flushes and night sweats are not the only symptoms that appear out of nowhere. Many women are unprepared for the fact that they may also face hair thinning. Unlike postpartum hair loss, hair loss in menopause is irreversible unless hormone replacement therapy is introduced.

Oestrogen increases the amount of time that hair spends in the growing phase — so when oestrogen declines, hair loses these protective effects.

Additionally, androgenic effects of testosterone can be intensified — where testosterone’s metabolite dihydrotestosterone (DHT) can produce progressively weaker hair due to the follicle’s failure to thrive [4]. When menopausal symptoms are present, a saliva hormone test can assess the levels of estradiol, progesterone and testosterone, and help both patient and practitioner decide on the best therapeutic strategy.

PCOS: This common female endocrine disorder is based on a cluster of symptoms, with hyperandrogenism taking centre stage [5]. In PCOS, elevated androgens cause women to lose scalp hair while simultaneously growing hair in places where women certainly do not want it — face, chest and back. Although there is no cure for PCOS, treatment is usually focused on managing symptoms through a laboratory workup of saliva steroids and blood levels of HbA1c and fasting insulin.

Thyroid Hormone and Hair Loss

Thyroid hormone regulates pretty much every process in our body. When the thyroid system becomes underactive — as with hypothyroidism — our metabolism slows down and the lesser important body functions get less attention. Sadly, hair and skin typically suffer first [8]. In hypothyroidism, hair tends to be dry, brittle, dull and diffusely thinned out — even eyebrow hair can fall out [9]. When there is too much thyroid hormone (Graves’ disease), hair will also fall out.

Accompanying symptoms of thyroid disease are noticeable in energy levels and mood. Hypothyroidism tends to make people feel tired, sluggish, depressed and constipated. Hyperthyroidism can manifest in anxiety, sleep problems, restlessness and irritability. If symptoms are present, our Essential Complete Thyroid Testing Profile (Blood Spot) measures TSH, Free T4, Free T3 and TPO antibodies from a simple finger-prick at home. In most cases, hair grows back once thyroid abnormalities are treated.

Nutritional Factors in Hair Loss

Ferritin and Iron Deficiency

If you think of iron as the merchandise in the front of the store, ferritin is the storage warehouse in the back. Serum ferritin is a powerful screening tool for iron deficiency. Hair follicles actually hold on to ferritin — when the body is low in iron, it can pull ferritin from places like hair follicles, deemed less important than red blood cell production. The resulting effect is diffuse hair loss. If hair loss is related to insufficient iron, correcting anaemia should allow hair to grow back. Screening for low serum ferritin levels is important before supplementing, as iron overload can be toxic [7].

Vitamin D — The Sunshine Vitamin and So Much More

Vitamin D is an important nutrient essential to immunity, bone health and many other processes. With regard to hair, it helps create new hair follicles by initiating the anagen phase through regulating the expression of genes required for hair follicle cycling. Researchers have found suboptimal serum vitamin D levels in women with telogen effluvium or female pattern hair loss [10], and patients with alopecia areata also have low serum vitamin D levels [11]. Emerging clinical research recommends evaluating serum vitamin D levels in patients with hair loss [12].

Vitamin B12 — The Energy Vitamin

To keep hair follicles active, you need healthy blood flow — oxygen-rich red blood cells feed the hair follicles. Vitamin B12 promotes healthy hair growth by assisting in the production of these red blood cells. B12 deficiency is usually more prominent in people with digestive issues, older adults, vegans, vegetarians, and those with excessive alcohol intake.

Clinical Evaluation: Talk to Your Doctor

A laboratory workup for hair loss is commonly performed. Additional questions that may help narrow down a differential diagnosis include [13]:

When did the hair loss start? A sudden onset may be suggestive of a disruption of the hair cycle.
Where is the hair loss most prominent? Diffuse shedding may indicate disruption of the hair cycle, while patterned thinning could be attributed to hormonal dysregulation.
What is the normal hair care routine? Certain hair care practices can have a tremendous impact on hair health.

With proper evaluation and appropriate testing for hormonal imbalances or nutritional deficiencies, help is on the way.

References

Shin H, et al. Acute Stress-Induced Changes in Follicular Dermal Papilla Cells and Mobilization of Mast Cells. Ann Dermatol. 2016;28(5):600–606.
Dinh QQ, Sinclair R. Female pattern hair loss: current treatment concepts. Clin Interv Aging. 2007;2(2):189–99.
Thom E. Stress and the Hair Growth Cycle: Cortisol-Induced Hair Growth Disruption. J Drugs Dermatol. 2016;15(8):1001–4.
Ramos PM, Miot HA. Female Pattern Hair Loss: a clinical and pathophysiological review. An Bras Dermatol. 2015;90(4):529–43.
Gersh F. PCOS SOS. 2018: Integrative Medical Group of Irvine.
Deloche C, et al. Low iron stores: a risk factor for excessive hair loss in non-menopausal women. Eur J Dermatol. 2007;17(6):507–12.
Trost LB, et al. The diagnosis and treatment of iron deficiency and its potential relationship to hair loss. J Am Acad Dermatol. 2006;54(5):824–44.
Contreras-Jurado C, et al. Thyroid hormone signaling controls hair follicle stem cell function. Mol Biol Cell. 2015;26(7):1263–72.
van Beek N, et al. Thyroid hormones directly alter human hair follicle functions. J Clin Endocrinol Metab. 2008;93(11):4381–8.
Rasheed H, et al. Serum ferritin and vitamin D in female hair loss: do they play a role? Skin Pharmacol Physiol. 2013;26(2):101–7.
Lee S, et al. Increased prevalence of vitamin D deficiency in patients with alopecia areata. J Eur Acad Dermatol Venereol. 2018;32(7):1214–1221.
Banihashemi M, et al. Serum Vitamin D3 Level in Patients with Female Pattern Hair Loss. Int J Trichology. 2016;8(3):116–20.
Mirmirani P. Managing hair loss in midlife women. Maturitas. 2013;74(2):119–22.

Originally by Dr. Kate Placzek, ZRT Laboratory. Reproduced with permission. Last reviewed: May 2026.

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