Glucose, Plasma
Test ID:
702971
CPT code:
82947
Synonyms:
Blood Sugar
Fasting Blood Sugar
Random Blood Glucose
Clinical Use:
Diagnose diabetes mellitus; evaluate disorders of carbohydrate metabolism including alcoholism; evaluate acidosis and ketoacidosis; evaluate dehydration, coma, hypoglycemia of insulinoma, neuroglycopenia. A fasting glucose >125 mg/dL on more than one occasion is adequate for the diagnosis of diabetes mellitus. An OGTT is not necessary in this setting. Infants, especially with tremor, cyanosis, convulsions, and respiratory distress should have stat glucose, particularly if there is maternal diabetes, postmaturity, asphyxia, hemolytic disease of the newborn, or possible sepsis. Babies too large or small for gestational age should also have glucose in the first 24 hours of life. Random blood sugars can be used to monitor therapy in diabetics or evaluate presence of insulinoma.
Test Information:
Recent evidence revealed a diurnal variation in FPG, with mean FPG higher in the morning than in the afternoon, indicating that many cases of undiagnosed diabetes would be missed in patients seen in the afternoon. Glucose concentrations decrease ex vivo with time in whole blood because of glycolysis. The rate of glycolysis, reported to average 5% to 7% [approximately 0.6 mmol/L (10 mg/dL)] per hour, varies with the glucose concentration, temperature, white blood cell count, and other factors. Glycolysis can be attenuated by inhibition of enolase with sodium fluoride (2.5 mg fluoride/mL of blood) or, less commonly, lithium iodoacetate (0.5 mg/mL of blood). These reagents can be used alone or, more commonly, with anticoagulants such as potassium oxalate, EDTA, citrate, or lithium heparin. Although fluoride maintains long-term glucose stability, the rate of decline of glucose in the first hour after sample collection in tubes with and without fluoride is virtually identical. (Note that leukocytosis will increase glycolysis even in the presence of fluoride if the white cell count is very high). After four hours, the glucose concentration is stable in whole blood for 72 hours at room temperature in the presence of fluoride. In separated, nonhemolyzed, sterile serum without fluoride, the glucose concentration is stable for eight hours at 25°C and 72 hours at 4°C. Glucose can be measured in whole blood, serum, or plasma, but plasma is recommended for diagnosis. The molality of glucose (ie, amount of glucose per unit water mass) in whole blood and plasma is identical. Although red blood cells are essentially freely permeable to glucose (glucose is taken up by facilitated transport), the concentration of water (kg/L) in plasma is approximately 11% higher than that of whole blood. Therefore, glucose concentrations in plasma are approximately 11% higher than whole blood if the hematocrit is normal. Glucose concentrations in heparinized plasma are reported to be 5% lower than in serum. The reasons for the latter difference are not apparent, but may be attributable to the shift in fluid from erythrocytes to plasma caused by anticoagulants. The glucose concentrations during an OGTT in capillary blood are significantly higher than those in venous blood [mean of 1.7 mmol/L (30 mg/dL), equivalent to 20% to 25%], but the mean difference in fasting samples is only 0.1 mmol/L (2 mg/dL). Although methods for glucose analysis exhibit low imprecision at the diagnostic decision limits of 7.0 mmol/L [(126 mg/dL), fasting] and 11.1 mmol/L [(200 mg/dL), postglucose load], the relatively large intraindividual biological variability (CVs of approximately 5% to 7%) may produce classification errors. On the basis of biological variation, glucose analysis should have analytical imprecision <3.4%, bias <2.6%, and total error <8.0%.
Specimen Type:
Plasma
Requested Volume:
Entire Collection
Minimum Volume:
0.5 mL
Container Type:
Gray-top (sodium fluoride) tube
Patient Preparation:
Blood should be drawn in the morning after an overnight fast (no caloric intake for at least eight hours), during which time the individual may consume water.
Collection:
Label specimen as plasma. Mix well.
Storage Instructions:
Maintain specimen at room temperature.
Stability Requirements:
Temperature |
Period |
---|---|
Room temperature |
14 days |
Refrigerated |
14 days |
Frozen |
14 days |
Freeze/thaw cycles |
Stable x3 |
Rejection Criteria
Gross hemolysis; improper labeling
Return Back to Test Directory
MCI Diagnostic
Providing top patient care with fast results.
Hours of Operation
Mon - Sat: 7 AM-11 PM
Sun: 7 AM-3 PM
COVID-19 Drive-Thru Hours
Mon-Fri: 9 AM-6 PM
Federal Holidays - CLOSED
More Information - Click Here
Government Contract
DUNS # 125722608
Cage Code: 3FPQ3
COVID-19
COVID-19 Fee & Pricing