Introduction: Spurious hyperphosphatemia is a relatively common phenomenon in patients with monoclonal gammopathy which can compromise patient safety. A cost-effective routine method is desirable for laboratories to reduce or eliminate the protein interference.
Methods: A protein free sample was obtained after precipitation with PEG-6000 (polyethylene glycol). S-phosphate concentration was measured with routine wet chemistry method in normal and monoclonal gammopathy samples before and after precipitation. Monoclonal samples were also measured by dry chemistry that includes an ultrafiltration step. The protein pattern before and after precipitation was checked by electrophoresis.
Results: No effect of PEG precipitation on S-phosphate concentration was demonstrated in normal serum. After PEG precipitation of proteins in monoclonal gammopathies serum wet chemistry gave the same results as dry chemistry i.e. after ultrafiltration.
Conclusion: PEG precipitation of proteins offers a cost-effective method to eliminate protein interferences in monoclonal gammopathies.
Keywords: Ig G kappa; Immunoglobulin; Interference; PEG; Phosphate; Vitros.
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