DDAVP is used to increase a mild deficiency of factor VIII; a side effect is fluid retention, as evidenced by a 5% weight gain in 3 days. Stiff, swollen, painful knee joints indicates hemarthrosis, which is an indication the hemophilia A is worsening, not an adverse effect of the medication. Avascular necrosis, a complication of hemarthrosis due to hemophilia A, is characterized by limited passive abduction of the hip. This indicates increasing severity of the disorder, not an adverse effect of therapy. DDAVP is not associated with hyperkalemia, which manifests as peaked T-waves on electrocardiogram.