Validation of hemolysis index thresholds optimizes detection of clinically significant hemolysis

Am J Clin Pathol. 2015 Apr;143(4):579-83. doi: 10.1309/AJCPDUDE1HRA0YMR.

Abstract

Objectives: Automated hemolysis index (HI) measurement has standardized the identification and gradation of sample hemolysis.

Methods: This study evaluates whether clinically significant changes in the concentration of intracellular analytes occur at manufacturer-recommended automated HI thresholds (HI ≥3, >25 mg/dL hemoglobin).

Results: Adult outpatient results for serum potassium (K+), magnesium (Mg), lactate dehydrogenase (LDH), and aspartate aminotransferase (AST) were analyzed. Mean ± SD analyte concentration and distribution within the reference interval (RI) were calculated for each HI group (1-7). Potassium results with an HI of 4 or more demonstrated clinically significant differences (≥0.5 mmol/L) in mean K+ concentration and RI classification compared with non-hemolyzed samples (HI = 1). LDH and AST showed clinically significant differences (+20%) for an HI of 3 or more. For Mg, only the group with an HI of 7 demonstrated a clinically significant difference (>25%); however, the number was low.

Conclusions: Mean measured potassium concentrations are not clinically significantly affected by hemolysis at the manufacturer-recommended HI threshold, while AST and LDH are. Aligning reporting of sample hemolysis with clinically significant changes provides clinically meaningful alerts regarding this common pre-analytic error.

Keywords: Automated chemistry; Hemolysis; Preanalytic error; Specimen integrity.

Publication types

  • Validation Study

MeSH terms

  • Adult
  • Aspartate Aminotransferases / blood
  • Blood Chemical Analysis / instrumentation
  • Blood Chemical Analysis / standards*
  • Hemoglobins / analysis
  • Hemolysis*
  • Humans
  • L-Lactate Dehydrogenase / blood
  • Magnesium / blood
  • Potassium / blood
  • Reference Values

Substances

  • Hemoglobins
  • L-Lactate Dehydrogenase
  • Aspartate Aminotransferases
  • Magnesium
  • Potassium