Two cases of spurious hyperphosphataemia in patients with multiple myeloma are presented. An unreduced phosphomolybdate method without dialysis was used and the falsely raised values are shown to be due to the formation of a proteinaceous suspension in the reaction mixture. Such interference may be more prevalent than is generally recognized, and care should be taken to identify the problem in patients with myeloma.
PetterssonTHortlingLTeppoAMTottermanKJFyhrquistF. Phosphate binding by a myeloma protein. Acta Med Scand1987; 222: 89–91.
4.
SonnenblickMEylathUBriskREldadCHershkoC. Paraprotein interference with colorimetry of phosphate in serum of some patients with multiple myeloma. Clin Chem1986; 32: 1537–9.
5.
McCloskeyEVGallowayJMorganMAKanisJA. Pseudohyperphosphataemia in multiple myeloma. BMJ1989; 299: 1381–2.
6.
MaclinEYoungD.Automation in the Clinical Laboratory. In: TietzN, ed. Textbook of Clinical Chemistry.Philadelphia: W B Saunders, 1986: 236–83.
