LDH levels in patients with PNH before and during eculizumab treatment. Initiation of eculizumab dosing is indicated at time 0 on the x axis. LDH values are shown for 11 patients with PNH for 25 weeks before and 64 weeks during eculizumab treatment. (Normal) Upper limit of normal of the LDH range at the Leeds Teaching Hospital. The dashed line indicates off-scale points from one patient with a peak value of 12 100 IU/L. Two patients who experienced a return of serum hemolytic activity during treatment are identified (patients 1 and 2).