Is the turbidimetric immunoassay of haptoglobin phenotype-dependent?

Abstract

Comparison of the turNdirnetric immunossay of haptoglobin with a reference method (the RID technique with appropriate correction for phenetype) clearly showed the turbidimetric assay to be phenotypedependent. Correction f~ctors for the three main phenotypes were calculated and reference values determined.The observed overall reference range of haptoglobin, irrespective of the phenotype, was 0.56-3.76 g/L. After correction for phenotype, reference values for the three types were: Hp 1-1 : 0.77-2.49; Hp 2-1:0.86-4.76; and Hp 2-2:0.48-3.15 g Hp/L, From our reference values for the several phenotypes of haptoglobin it may be argued that phenotyping is desirable only when the uncorrected haptoglobin value, determined by turbidimetry, is within the range 0.38-0.98 g/L. Limited to hemolytic diseases, phenotype determination can be omitted beyond this range.

Unexpected laboratory results in cold agglutinin disease

“…The other possible reason may be that the patient had a phenotype variant of Hp that the method used cannot identify. Studies have shown that the measurement of some phenotypes of Hp by immuno-turbidimetric methods may lead to incorrect results [9]. The previous low Hp level laboratory result of the patient, in spite of a moderate level of anemia and normal hemolysis markers, strengthens this possibility.…”

Effects of haptoglobin polymorphisms and deficiency on susceptibility to inflammatory bowel disease and on severity of murine colitis

“…These differences affect serum levels and they have been related to the lower anti-inflammatory capacity of Hp2 . Different correction factors have been proposed,43 although it is still not clear how exactly the corrections should be applied. Therefore we may be underestimating the real differences between the genotypes.…”

Detection of Hemoglobin-Based Oxygen Carriers in Human Serum for Doping Analysis: Screening by Electrophoresis

“…The use of concentrated antibodies is highly advised to ensure efficient removal of the Hb-Hp complexes in the cases of abnormally high Hp concentrations. Although the polyclonal antibodies used are reactive against the three common Hp phenotypes (1-1, 2-1, and 2-2), some differences in immune reaction related to phenotype must be envisaged (12,13 ). Nevertheless, the efficiency of Hp removal can be validated by checking that the electropherogram is not changed by use of more concentrated antibodies.…”