Lab Med Online.  2020 Jul;10(3):197-201. 10.3343/lmo.2020.10.3.197.

Performance Evaluation of Serum IgD Quantification by the SPAPLUS Turbidimetric Analyzer and Determination of a Reference Interval of IgD in the Korean Population

  • 1Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Korea
  • 2Seoul Clinical Laboratories, Seoul, Korea


IgD is an immunoglobulin isotype that accounts for <1% of the total serum immunoglobulin, and IgD level changes can be observed in specific clinical situations. Herein, we evaluated the analytical performances of serum IgD quantification by the SPAPLUS turbidimetric analyzer (The Binding Site, UK), and determined a reference interval of IgD in the Korean population.
Precision, linearity and comparison with BNII (Siemens Healthineers, Germany) were assessed, and a reference interval was established according to the Clinical and Laboratory Standards Institute guidelines.
Repeatability ranged from 0.78% to 2.14%, and the within-laboratory precision ranged from 4.10% to 5.40% for three concentrations. The coefficient of determination (R2) was 0.9996 for the analytical measurement range. The IgD concentration showed a correlation between SPAPLUS and BNII (y=0.890x-1.852, r=0.984). However, IgD concentrations tended to be lower in SPAPLUS compared to those in BNII at concentrations >100 mg/L. The established upper limit of the reference interval was 53.6 mg/L.
The SPAPLUS shows good analytical performance for serum IgD quantification.


Analytical performance; IgD; Monoclonal gammopathy; Reference interval; Turbidimetry
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