Hypocalcemia-induced pustular psoriasis of von Zumbusch. New experience with an old syndrome.

Hypocalcemia occurs in patients with psoriasis vulgaris, pustular psoriasis of von Zumbusch, and impetigo herpetiformis. In most cases hypocalcemia is caused by accompanying hypoalbuminemia, yet reductions in ionized serum calcium concentrations due to hypoparathyroidism or malabsorption have been reported. We report the case of a patient with surgical hypoparathyroidism in whom hypocalcemia precipitated typical pustular psoriasis of von Zumbusch. The psoriasis rapidly cleared on two occasions when the patient's serum calcium was corrected by therapy with oral calcium and vitamin D or its analogues, and reappeared when treatment was discontinued. The patient's psoriasis cleared on a third occasion when her serum calcium level returned to normal with a calcium infusion. Hypocalcemia can precipitate pustular psoriasis of von Zumbusch in susceptible persons. These psoriatic flares are due not to abnormal circulating levels of parathyroid hormone or vitamin D metabolites but to hypocalcemia.