This “mature” hairline is not considered balding; the Norwood III is considered the first evidence of balding in androgenetic alopecia (male pattern baldness). In studying the Norwood charts, we see that usually the most advanced balding is known as a class VII, and that there are also Type “A” variants in which the forelock in the middle tends to recede along with the fronto-temporal areas, and in which there is be less overt crown loss than in the regular III, IV, and V patterns.
Contact dermatitis causes skin inflammation and when severe it can affect the hair follicles as well. It can either be due to some irritant making contact with the skin of the eyebrows or due to a substance to which a person has an allergy. This gives rise to the two types of contact dermatitis – irritant contact dermatitis or allergic contact dermatitis. Substances that could cause contact dermatitis at the eyebrow includes eye makeup including eyebrow pencils, hair removal creams and waxes, other cosmetics, hair dyes and scalp hair styling products.
Thyroid hormone receptors were detected in both dermal and epithelial compartments of the human pilosebaceous unit.[48] T4 and T3 decrease the apoptosis of hair follicles and T4 prolongs the duration of anagen in vitro.[49] Thyroidectomy delays initiation of anagen. Administration of thyroxine advances anagen, initiation of which is however delayed once toxic doses are given. Therefore, ratio of telogen to anagen hairs is increased in hypothyroidism as well as hyperthyroidism.[50] Thus, the hair follicles are affected in thyroid disorders, and madarosis is caused due to disturbances in hair cell kinetics. Hypothyroidism is associated with generalized hair loss probably due to coarse, dull, and brittle hair with reduced diameter.[51] The eyebrows and eyelashes may also be lost. Loss of lateral one-third of eyebrows known as Hertoghe sign[38] is a characteristic sign of hypothyroidism.[52] Some people also refer to it as Queen Anne's sign,[53] after Anne of Denmark whose portrait with shortened eyebrows has been interpreted by some as indicative of the presence of goiter, even though such a fact has not been proved by any known sources of information. Madarosis may even be the presenting sign in hyperthyroidism.[21] In hyperthyroidism, there is thinning with breaking off and shortening of hair.[54] Madarosis can also occur in hypopituitarism, hypoparathyroidism,[21] and hyperparathyroidism.[55]
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