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Table 1 Within-run and between-day precision of measurement of free β-hCG and PAPP-A, using Siemens Control Modules and human pooled sera on automated platform Immulite 1000

From: The impact of temporal variability of biochemical markers PAPP-A and free β-hCG on the specificity of the first-trimester Down syndrome screening: a Croatian retrospective study

   Free β-hCG (ng/ml)   PAPP-A (mIU/ml)  
Sample Control Module LFBCM Human serum Control Module LPCCM Human serum
  Control 1 Control 2 Control 3   Control 1 Control 2  
Target 5.1 23.8 74.2   0.40 1.96  
2SD Range (4.2-6.4) (19.8-27.8) (63.6-90.8)   (0.32-0.48) (1.70-2.22)  
Within-run        
Mean 4.84 24.1 72.8 66.6 0.41 1.94 2.58
SD 0.15 1.12 3.50 2.40 0.01 0.06 0.17
CV* (%) 3.09 4.65 4.81 3.60 2.44 3.09 6.59
Between-run        
Mean 4.75 22.66 71.66 61.7 0.38 1.94 2.39
SD 0.31 1.70 5.25 4.13 0.02 0.11 0.21
CV* (%) 6.52 7.50 7.32 6.69 5.26 5.67 8.79
  1. CV* - coefficient of variation