Plasma zinc is decreased only in generalized pustular psoriasis.

Plasma and cutaneous zinc were studied in 22 psoriatic patients and 14 controls. The psoriatics were divided into three groups: 10 extensive psoriasis vulgaris, 5 palmoplantar psoriasis and 7 extensive pustular psoriasis. Low plasma zinc and decreased in vitro chemotaxis of polymorphonuclear leukocytes were found only in extensive pustular psoriasis, whereas zinc was not decreased but rather elevated in skin. This explains why conflicting results on plasma zinc have been previously reported in psoriasis and confirms that cutaneous zinc depletion is not a feature of psoriasis.