DIFFUSE HAIR LOSS
The normal hair cycle results in replacement of every hair on scalp every 3 to 5 yrs, with the consequence that between 50 to 150 telogen hairs are shed each day. While there is some seasonal variation in the amount of hair lost every day, this number remains fairly uniform throughout life. Most this hair loss passes unnoticed, particularly when the hair is short.
- Autoimmune disorders
- Acute or chronic disease related
Malnutrition is a common cause of hair loss. Anemias of any type are many times can be diagnosed as an incidental finding while investigating hair loss. Likewise, many deficiencies such as Vit.B 12, Vit.D, Vit.A, and Vit.E are known to cause hair loss. Hypervitaminosis particularly of Vit.A is also known to cause DHL.
Various hormonal disturbances cause hair loss.
Thyroid- Epidermal thickness is reduced in Hypothyroidism and rate of cell division is increased in Thyrotoxicosis.
Changes in cortisol and aldosterone levels whether due to underlying pathology or iatrogenic leads to hair loss.
Sex hormones both androgens and estrogens have a great influence on hair. Fluctuations in the balance of both can cause DHL which further can lead to patterned hair loss.
Hair loss due to hormonal changes is commonly faced by females more than males as they are bound to undergo hormonal changes during pregnancy and menopause.
Metabolic disorders can be inborn errors of metabolism such as phenylketonuira and G6PD, or can be transient phases of imbalance of various electrolytes. Changes in internal milieu can lead to hair loss.
Many therapeutic agents when administered are known to cause hair loss, such as-:
- Cytostatic Drugs
- Antithyroid drugs
- Hypolipedemic agents- used for increased level of cholesterol
- Retinoids- used in skin treatments
- NSAIDS- Painkillers when abused
- Oral contraceptives
Several autoimmune disorders like SLE, RA, and Psoriasis cause hair loss due to lesions involving scalp or therapy with cytotoxic drugs. Long term management of hair loss is essential.
ACUTE OR CHRONIC DISEASE RELATED-
Any illness causes hair loss as an immediate effect or even after 3 months of illness. A phase of telogen effluvium is seen after 3 months of illness which are known as magical 3 months.
Stress can cause unexplained bout of hair loss due to hormonal and metabolic changes associated with stress. It can set in a vicious cycle where the stress is caused due to hair loss and it further worsens the hair loss.