Iron Deficiency Developing in Patients with Homozygous Hypercholesterolaemia on Long-term Plasmapheresis is Significantly Contributed to by Extracorporeal Haemolysis

Abstract

Patients with homozygous hypeicholesterolaemia are notoriously refractory to pharmacologic intervention, leaving regular long-term plasmapheresis as one of the most effective forms of therapy. In this situation we noted the universal development of anaemia; accordingly, its pathogenesis was investigated in a stable cohort of patients over a two year period. Radionuclide studies were carried out in 8 of the 9 available individuals: of these 3 who were not on treatment and 3 out of 5 on the apheresis programme had mean red cell lifespan below the lower level of our normal range. The creation of an arterio-venous fistula and subsequent performance of plasma exchange procedures every two weeks was followed by a falling haemoglobin concentration and the appearance of hypochromasia and microcytosis. The latter was the result of substantial loss of iron through venesection, in the discard plasma and by a transient peak of the iron in the urine: the last two compartments were studied using inductively coupled plasma atomic emission spectrometry (ICP-AES). Such depletion could not be compensated for by a dietary intake of iron that barely met the recommended daily allowance whereas the anaemia reversed readily on oral supplementation. This is the first report of extracorporeal haemolysis in this clinical setting and recognition of its pathophysiology directly influences management. Thus, oral iron supplementation should prevent anaemia and its symptoms whilst also circumventing the paradoxical hyperviscosity that might otherwise occur from iron deficiency.

Keywords:

• Plasma exchange
• hypercholesterolaemia
• extracorporeal haemolysis