A case of atypical IgA paraprotein interference on multiple chemistry assays: How to deal with it

TL;DR

This paper presents a case where IgA paraproteins interfere with chemistry assays, and suggests methods to mitigate the interference.

Contribution

The paper introduces practical solutions for handling IgA paraprotein interference in chemistry assays.

Findings

IgA paraprotein interference affects bilirubin, phosphate, and iron measurements in wet chemistry systems.

Deproteinization with polyethylene glycol or dilution with normal serum mitigates the interference.

Dilution with normal saline was ineffective in resolving the interference.

Abstract

This case report discusses how paraproteins interfere with multiple chemistry analyses and protocols to overcome such obstacles. A serum specimen containing two monoclonal IgA (llight chain) paraproteins is subjected to a battery of tests on three wet chemistry platforms - AU5800, Cobas Pure, and Alinityci; the results were compared with those on a Vitros 350/ ECiQ dry chemistry platform. Paraprotein interference was found to affect the bilirubins, inorganic phosphate, and iron, whose repeat runs were also found to be irreproducible. Dilution with normal saline also failed to produce a satisfactory effect. Deproteinization by polyethylene glycol and dilution of the specimen with a normal serum specimen were observed to produce desirable results. Interference by IgA paraprotein on measurement of the bilirubin, phosphate, and iron in the wet chemistry system can be mitigated either by deproteinization or by dilution with normal serum.

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