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Hair loss in men and women is essentially an imbalance between the resting phase and the growth phase in the hair growth cycle. Many factors can influence this imbalance. It could be age, poor diet, stress, hormones, genetic predisposition, excessive use of hair dye and curlers, and smoking.
Hormonal changes are the most common cause of hair loss in women. Following hormones play an important role in hair loss.
Prolactin
Prolactin is a hormone produced mainly by the pituitary gland, which is located at the base of the brain. The hormone is also produced by the central nervous system, the immune system, skin, uterus, and even the mammary glands. [1] It has a number of functions, chiefly, milk production in the breast after childbirth. So, during pregnancy and breast feeding, it is normal for prolactin levels to rise. Apart from stimulating milk production, it also regulates body fluids, regulates immune system, and has an important role to play in metabolism.
Normal prolactin levels vary from 2 to 0.025 mg/ml depending on age and the time of menstrual cycle, but prolactin levels higher than 0.2 mg/ml are considered pathological. This is known as hyperprolactinemia. [2]
Several studies have reported that hyperprolactinemia can cause hair loss, including male-pattern baldness (androgenic alopecia). For example, a German study indicated hyperprolactinemia as the cause of hair loss along with irregular menstrual bleeding, seborrhoea (excessive discharge of sebum from sebaceous glands), and persisting acne. [2]
Similarly, another study found that hyperprolactinemia along with hypothyroidism is the cause of androgenetic alopecia in women. According to the researchers, 0.4 mg/ml of prolactin significantly inhibits hair shaft elongation and induces premature catagen development in which hair stops growing and the follicle loosens the grip on the hair bulb, resulting in hair loss.[3] They also found that prolactin is locally produced in the skin and can cause hair loss because of skin s response to stress.
Cortisol
Stress can significantly contribute to hair loss. According to Dr Seymour Weaver, a cosmetic dermatologist in the USA, hair follicles respond to stress by turning off hair growth. One of the consequences of stress, that is, hair loss, can be noticed only after 2 to 4 months after the stressful event occurs.
The culprit hormone in this case is cortisol or the stress hormone . Cortisol is produced by the adrenal glands because of the body s fight or flight response to threat, that speeds up body s metabolic rate and heightens the sense of awareness. Although, these changes can be beneficial in short term, prolonged stress causes higher cortisol production.
In their study on monkeys, scientists at University of Massachusetts in USA found that experimental animals with greater than 30 percent hair loss showed higher concentrations of hair cortisol as compared to controls who showed less than 5 percent hair loss. High cortisol levels causes hair loss in human beings as well, especially in those who are experiencing chronic pain, undergoing unemployment, engaging in shift work, or are diagnosed with acute heart problems, or showing alcohol-dependence. New-born infants who require hospitalisation in the neonatal intensive care unit also show higher cortisol levels. [4]
How do high cortisol levels impact hair loss? Hyaluronan and proteoglycans are important skin elements that are responsible for hair growth. High cortisol levels reduce the synthesis and accelerate the degradation of these two skin elements almost by 40 percent, say researchers. [5] This leads to shortened growth cycle of hair and consequent hair loss. Read more about Natural remedies for hormonal problems in women
DHT
DHT or dihydrotestosterone, is another hormone that along with genetic predisposition causes male pattern baldness, especially in men. DHT is derived from testosterone under the influence of the enzyme 5-alpha-reductase. This enzyme is of two types Type 1 and Type 2. Type 2 is mainly located in the hair follicles and converts testosterone into DHT. In men, approximately 70 percent of DHT is formed from the conversion of testosterone, while in women, DHT is formed from androstenedione, which is a steroid hormone that makes testosterone and oestrogen in the body.[6]
What happens is, DHT molecules along with its derivatives diffuse into genetically susceptible hair follicles and cause the anagen (growth) phase of the hair growth cycle to become progressively shorter. This process is called miniaturization of hair follicle. Miniaturization lengthens the telogen phase of the hair growth cycle in which the hair are less anchored to the scalp, resulting in hair fall.
Oestrogen
Oestrogen has an important role to play in the female pattern hair loss, in which hair density on the crown reduces progressively but not to the extent of baldness. This type of hair loss is commonly seen in post-menopausal women. Interestingly, high levels of oestrogen stimulates scalp hair growth in men, but inhibits hair growth by suppressing cellular function in the hair follicles.
In a Japanese study, researchers found that testosterone and oestrogen inhibited hair growth and the minimum effective doses of both hormones to suppress hair growth was around 0.05 mg/ml. [7]
Hair loss after childbirth is seen in many women. This is because oestrogen levels rise during and after pregnancy and then dip causing hair loss.
Excess oestrogen can also be caused by obesity, perimenopause, and exposure to endocrine disruptors such as cosmetics, plastic, food contaminants, and certain drugs.
Insulin
There is a positive co-relation between hair loss and insulin, to be more precise insulin resistance. This has been conclusively shown by various studies. For example, Veikko Matilainen and his colleagues found that men under 35 years of age with an early onset of alopecia, showed an increased risk of insulin resistance associated disorders such as obesity, high blood pressure, and high cholesterol. [8]
Insulin resistance is a condition in which the body s cells become resistant to insulin due to multiple factors such as poor lifestyle choices and genetic predisposition. With insulin resistance, pancreas produce more and more insulin until they can no longer produce sufficient insulin to meet the body s demand; then, blood sugar levels rise. Elevated blood sugar levels lead to higher cortisol levels and free radicals. And high cortisol levels, as seen earlier, are definitively associated with hair loss.
Thyroid
Hair loss is one of the main symptoms of hypothyroidism and, paradoxically, hyperthyroidism. Hair loss involves the whole scalp rather than discrete areas of the scalp.
Thyroid hormones affect every cell in the body, including the cells of hair follicle. They also regulate the
Scientists at University of Lubeck, Germany, reported that thyroid hormone prolong the growth phase of hair cycle and inhibit spontaneous rest phase of the hair growth cycle. So, low levels or very high levels of thyroid hormone cause the sudden onset of rest phase, leading to hair loss. [9]
Hair regrowth resumes after the thyroid disorder treatment. Another study, however, pointed out that thyroid treatment does not improve hair loss unless zinc supplements are added, as zinc deficiency is one of the causes of hypothyroidism as well as impairment of hair growth. [10]
Hair re-growth depends on what caused the hormonal imbalance in the first place. The causes, as seen, are many from genetic predisposition to poor diet to menopause. Sometimes, treating the hormonal imbalance can help reverse hair loss, and at other times, it may be necessary to choose hair restoration options.
Reference
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