A patient with paraproteinemia may have falsely elevated values for hemoglobin, mean cell hemoglobin (MCH) and mean cell hemoglobin concentration (MCHC).
Recognition - apparent discrepancy in results of an automated CBC:
(1) hematocrit and RBC count are consistent with each other
(2) hemoglobin and the indices calculated from hemoglobin are elevated relative to the hematocrit and RBC
The abnormal globulins in the serum may be precipitated by a number of mechanisms as reagents are added to the sample in an automated instrument (low pH, quarternary ammonium salts, other salts), resulting in an increased turbidity that is misread as hemoglobin.
Solutions:
(1) Estimate hemoglobin from hematocrit.
(2) Centrifuge the specimen, remove the patient's plasma and replace with an equal volume of isotonic diluent or normal plasma (see previous section).
(3) Perform a manual hemoglobin using a modified Drabkin reagent (made by adding a nonionic detergent).
Differential diagnosis:
(1) chylomicrons or fat (previous section)
(2) unstable hemoglobinopathy
(3) marked leukocytosis
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