ZINC CONCENTRATION IN PATIENTS WITH IRON OVERLOAD RECEIVING ORAL IRONCHELATOR 1,2-DIMETHYL-3-HYDROXYPYRID-4-ONE OR DESFERRIOXAMINE

Aims-To determine the changes in serum zinc concentration and the exte nt of urinary zinc excretion in patients with iron overload receiving the oral iron chelator 1,2-dimethyl-3-hydroxypyrid-4-one (L(1)) or des ferrioxamine (DFX), and to correlate these results with blood glucose concentration. Methods-Serum zinc and ferritin concentrations, urinary zinc and iron excretion were regularly assayed in 39 patients and the glucose tolerance test (GTT) was performed in each patient. Patients were segregated according to their GTT into normal, diabetic, and thos e with an abnormal GTT. The mean of L(1)- or DFX associated urinary zi nc excretion for each group was determined and compared with the other two groups and with normal value. L(1) associated urinary zinc excret ion was also compared with L(1) dose, serum ferritin values, and urina ry iron excretion. Results-Both DFX and L, were associated with a sign ificantly increased urinary zinc excretion (15.1 (7.3) mu mol/24 hours , 11.1 (6.0) mu mol/24 hours, respectively) compared with normal subje cts. In patients receiving DFX this increase only occurred in patients with diabetes mellitus. Both diabetic and non-diabetic patients recei ving L(1) treatment excreted more zinc than normal. Diabetic patients receiving L(1) or DFX excreted more zinc than non-diabetics receiving the same treatment. No correlation was found between urinary zinc excr etion and L(1) dose or patients' serum ferritin concentrations. In sev en patients receiving long term L(1) treatment a fall in serum zinc wa s observed from an initial 13.6 (1.6) mu mol/l to a final 9.6 (0.8) mu mol/l. In one patient this was associated with symptoms of dry skin a nd itchy skin patches requiring treatment with oral zinc sulphate. Con clusions-In contrast to DFX, L(1) treatment is associated with increas ed zinc loss. This, however, is modest and does not lead in most patie nts to subnormal serum zinc concentrations. In a few patients whose ne gative zinc balance may give rise to symptoms, zinc supplementation ra pidly corrects the deficit.