Hyperviscosity Syndrome in IgA Multiple Myeloma

Summary. Four cases of IgA multiple myeloma with raised serum or Plasma viscosity and clinical features of the hyperviscosity syndrome (HVS) are described. Plasmapheresis was effective in reducing blood viscosity and improving the clinical condition in all four patients. In three of four cases plasma viscosity studies showed an increase in viscosity at low temperature which in one patient was attributable to excess chylomicrons. Although rarely reported in the past, IgA myeloma has been the commonest cause of HVS in Cardiff and should be looked for in all cases of myeloma whatever the paraprotein type. Measurement of serum viscosity is essential for rational clinical management. Whole blood viscosity measurements, although technically more difficult, are also of great help in patient management.