Chemical or drug-induced:
(1) chemotherapeutic agents
(2) other drugs
(3) heavy metal poisoning (arsenic, cobalt, selenium, tellurium, thallium)
Endocrine and metabolic disorders:
(1) hyperthyroidism
(2) hypothyroidism
(3) androgeneitc (from excess androgens or increased sensitivity to androgens)
(4) malnutrition (diet, starvation, malabsorption)
(5) cachexia associated with advanced malignancy
(6) iron deficiency
Infection:
(1) syphilis
(2) tinea capitis
Autoimmune:
(1) systemic lupus erythematosus
Organ failure-related:
(1) chronic renal failure
(2) hepatic failure
Other:
(1) radiation exposure or therapy
(2) scarring alopecia
(3) alopecia areata
(4) telogen effluvium
(5) telogen gravidarum (postpartum alopecia)
(6) trichotillomania
(7) pressure-induced
