Hi Fungal infections (such as tinea capitis) , Folliculitis, Hypervitaminosis A, Iron deficiency or malnutrition in general Seborrheic dermatitis, a condition in which an excessive amount of sebum is produced and builds up on the scalp (looking like an adult cradle cap) is also a symptom of hormonal imbalances, as is an excessively oily or dry scalp. Both can cause hair thinning. consult dermatologist to look for cause and treatment...