That is a best example. Dandruff in modern medical textbooks is mentioned as the first symptom of the manifestation of seborrheic dermatitis. Those suffering from this complication will have symptoms of falling flakes, falling hair and itching. Itching is variable. It will depend upon patient to patient.
Some people scratch more and others very less.
It is not necessary that in every case of dandruff attack, there is a hair fall. Flaking is the most important symptom of a patient with dandruff. Dandruff can be easily diagnosed. If the treating physician scratches the scalp with he thumb, he can see a lot of flaking. Tests are not needed for diagnosing dandruff.