**8. Histopathology**

Iron deficiency anemia is also a causative factor of CDTHL, since follicles need iron to stimulate the anagen phase of the hair cycle [19]. The hair loss can be reversed with the iron supplementation. Iron deficiency without anemia is more controversial, as it has a potential relationship with CDTHL [20]. In the majority of cases, drug-induced CDTHL occurs mechanistically via the immediate anagen release [19]. It typically occurs within 6–12 weeks of treatment and progresses while on the medication. It, then, begins to resolve after the discontinuation of the drug [21]. To the best of our knowledge, no controlled trials showing a causal relationship for specific medications have been conducted; however, if a medication is suspected, it should be discontinued for a period of at least 3 months to examine its possible

Moreover, diet is associated with the hair condition. Therefore, each patient should be questioned for the protein intake. Eating disorders can also lead to hair loss. In a study, 67% of the

In the presence of hair loss, the key step is taking a thorough history of the patient. In addition, the affected areas of the scalp should be examined to determine the presence or absence of follicular orifices. It helps to distinguish the scarring and nonscarring alopecia [23]. In the presence of follicular orifices, nonscarring alopecia can be suspected, although further history

The diagnosis of TE is usually based on the patient's history, physical examination findings, and hair pull test results (**Table 2**) [10]. The recognition of diffuse, noninflammatory, nonscarring hair loss should raise the clinical suspicion for TE, when it occurs acutely and is preceded by a physiological or psychological stressor, in particular. In the majority of cases,

patients with TE had bulimia, while 61% had anorexia nervosa [22].

findings are useful to unveil the main cause [14].

scalp biopsy is not required [10].

**Table 2.** Diagnosis of telogen effluvium [10].

Anamnesis, clinical diagnosis

Hair pull test Trichogram

Light microscoby

Laboratory evaluation

Biopsy

Wash test

link to the hair loss [4, 14].

**7. Diagnosis**

130 Hair and Scalp Disorders

With the exception of TE induced by inflammatory disorders affecting the scalp, scalp biopsies of TE not show an inflammation. On the other hand, increased telogen follicles are the main histopathological finding [24]. Unlike androgenetic alopecia, the rate of vellus hair follicles does not increase [12].
