Diffuse hair loss
Hair is lost evenly from the whole scalp; this may, or may not, be accompanied by a thinning visible to others (Fig. 13.12). Some of the most common causes are listed in Table 13.2, but often a simple explana-tion cannot be found.
Telogen effluvium can be triggered by any severe illness, particularly those with bouts of fever or haemorrhage, by childbirth and by severe dieting. All of these synchronize catagen so that, later on, large numbers of hairs are lost at the same time.
The diffuse hair fall, 2–3 months after the provoking illness, can be mild or severe. In the latter case Beau’s lines may be seen on the nails. Regrowth, not always complete, usually occurs within a few months.
This is from other types of diffuse hair loss (Table 13.2).
This condition is unaffected by therapy, but patients can be reassured that their hair fall will be temporary.
The causes mentioned in Table 13.2 should be con-sidered, and the exclamation-mark hairs of the diffuse type of alopecia areata should be looked for. If no cause is obvious, it is worth checking the haemoglobin, erythrocyte sedimentation rate (ESR), ANF, serum iron, thyroxine and thyroid-stimulating hormone (TSH) levels. Also consider checking the serum free testos-terone and dihydroepiandrosterone sulphate levels in women with menstrual irregularities or hirsutism. However, it is true to say that often no cause for dif-fuse alopecia can be found.