Glucose (GLUC), Serum or Plasma

 CPT Code: 82947 
 Specimen: Serum or Plasma

Serum:  Entire collection

Plasma: 1 mL

 Minimum Volume:  0.5 mL
Container: Serum:  Red-top tube or gel-barrier tube
Plasma:  Gray-top (sodium fluoride) tube
Methodology: Enzymatic
Patient Preparation: Serum: Patient should fast for 12 hours.
Plasma:  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: Specimen should be free of particulate matter.  To prevent the appearance of fibrin in serum samples, complete clot formation should take place before centrifugation.  Glycolysis decreases serum glucose by approximately 5-7% per hour in normal uncentrifuged coagulated blood at room temperature.  Clotting time may be increased due to thrombolytic or anticoagulant therapy.
Reference Range: 65-99 mg/dL


Temperatures Period
Room Temperature 8 Hours
Refrigerated (4 ⁰C) 3 Days
Also stable for as long as 3 days at room temperature by addition of sodium iodoacetate or sodium fluoride (NaF) to the specimen.


Use: Glucose is the primary source of energy for all bodily functions. The blood glucose level is strictly regulated by several hormones, including insulin and glucagon.  Glucose measurements are used in the diagnosis and treatment of carbohydrate metabolic disorders including diabetes mellitus, idiopathic hypoglycemia, and pancreatic islet cell neoplasm.
Clinical Significance: High glucose is an indication of hyperglycemia. Other causes include nonfasting specimen; recent or current IV infusions of glucose; stress states such as myocardial infarct, brain damage, CVA, convulsive episodes, trauma, general anesthesia; Cushing disease; acromegaly; pheochromocytoma; glucagonoma; severe liver disease; pancreatitis; drugs (thiazide and other diuretics, corticoids, many others are reported to affect glucose).  
Low glucose is an indication of hypoglycemia.  Other causes include excess insulin, including rare insulin autoimmune hypoglycemia, surreptitious insulin injection, and sulfonylurea use.
Causes for Rejection: Gross hemolysis; patient not fasting; blood stored overnight on clot; improper labeling
Interfering Substances: Hemoglobin (hemolysate) at 1000 mg/dL decreases a GLUC result at 50 mg/dL by 11%.

Bilirubin (unconjugated) at 60 mg/dL increases a GLUC result at 50 mg/dL by 13%.
Lipemia at 200 mg/dL increase a GLUC result at 50 mg/dL by 10%.
Pralidoxime iodide (PAM) concentration of 512 µg/mL increases a GLUC result of 78 mg/dL by 17%.

Pralidoxime iodide (PAM) concentration of 1024 µg/mL increases a GLUC result of 204 mg/dL by 13%.