Upsala J Med Sci 91: 217, 1986 

Paper Spotted Blood Glucose for Quality Control of 
Reflectance Meters 

Henning von Schenck 
Department of Clinical Chemistry, Linkoping University, Linkoping, Sweden 

The usefulness of blood glucose results obtained with various teststrips and 
reflectance mters rely mainly on the quality of the strip and the skills of 
the analyst. Dependable qualitycontrol,therefore, remains a main task for the 
large hospital when decentralizing analysis of bloodglucose close to the pati- 
ent or to satellite laboratories. Adequate quality control has, however, been 
inhibited by the lack of blood that is resistant to glucolysis and still 
appropriate to teststrip chemistry. This study reports the applicability of 
filter paper sampling of capillary blood to quality control of decentralized 
glucose determination. 

Methods: Capillary blood (- 50 p) was applied on filter paper. A split sample 
was assayed with decentralized reflectance meters, i.e.: the Dextrostix Gluco- 
mter ( a s )  or the Reflotest-Glucose Reflomat and the ReflocheckClucose 
Reflocheck system (Boehringer Mannheim) and the result written on the filker 
paper. The papers were mailed once weekly to the laboratory. There, the spots 
were punched out and assayed as detailed in Clin Chem 35:706-709, 1985 with 
the routine laboratory procedure using glucose hexokinase. 

Results: The accuracy of the filter paper method was 0.96X + 0.4 (n=68, ~0.98) 
with intra- and interassay C.V. of 1.2-5.2% and 9.9-4.4%, respectively. Ana- 
lytical recovery was 80%. The results were stable during 3 weeks. The regres- 
sion equations for the glucmter systems were Y= 1.04X - 0.3 (n=50, r=C).96) 
and Y= 0.98X + 0.3 (n=46, r=0.98). For the Reflocheck Y= 0.95X + 0.5 (n=46, 
~0.95) and the Reflomat systems Y= 1.03X + 0.3 (n=39, Y=0.96), Y= 0.86X + 1 . 1  
(n=43, ~0.96) and Y= 0.85X + 0.9 (n=43, ~0.95). 

Conclusion: The filter paper method is useful for quality control of decentra- 
lized glucose determination. Problem cases can be identified as exemplified 
by our finding of 3 different regression equations for the same reflectance 
meter system, one of which gave results very close to the identity line. 

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