LOGARITHMIC QUANTITATION MODEL USING SERUM FERRITIN TO ESTIMATE IRON OVERLOAD IN SECONDARY HEMOCHROMATOSIS

Nineteen children and adolescents receiving repeated transfusions and subcutaneous desferrioxamine treatment were investigated in an attempt to quantitate iron overload non-invasively. Before patients were star ted on desferrioxamine individual relationships were correlated for 12 to 36 months between transfused iron, absorbed iron estimated gastro- intestinally, and increasing serum ferritin concentrations. Patients w ith inflammation, increased liver enzymes, or haemolysis were excluded from analysis. The relationship between the variables could be descri bed by a logarithmic regression curve (y=transfused iron [plus eventua lly gastrointestinally absorbed iron]=iron overload=a+b log [x=serum f erritin]) for each individual patient. All patients showed close corre lation (R(2)) between x and y (median R(2) of 0.909, 0.98, and 0.92 in thalassaemia, aplastic anaemia, and sickle cell anaemia patients, res pectively). When started on desferrioxamine, current serum ferritin co ncentrations were used to derive the iron overload from each individua l regression curve. The derived estimated iron overload ranged from 0. 6 g to 31 g. Left ventricular dilatation was observed in three patient s with beta thalassaemia and in one patient with aplastic anaemia with median iron overload of 20.7 (14.1-31.3) g and 24.0 g respectively. H ypothyroidism was found in four patients with beta thalassaemia and on e patient with aplastic anaemia with iron overload between 14.7 (6.8 a nd 26.1) g and 15.1 g respectively. Human growth hormone deficiency wa s detected in three patients with beta thalassaemia with an iron of 4. 2 (3.5-6.8) g; all three had excellent desferrioxamine compliance.