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Test Code GLC Glucose

Specimen and Container/Tube

Specimen Type: Plasma

Preferred Specimen: Li-Heparin Mint Green Top

Other Acceptable specimens: Serum/Gold Top, Serum/Red Top, Plasma/Lavendar K2 Top, Plasma/NaF/Na2EDTA, Plasma/KF/Na2EDTA, Plasma/NaF/K-Oxalate

Specimen Stability

Storage Temperature

Stability

Room temperature

Spun - 8 hours*

Unspun - 6 hours**

Refrigerated

Spun - 3 days

Unspun - 6 hours**

Frozen

 Not Acceptable

Note: 

*Specimen received spun greater than 8 hours from collection will be cancelled with the following comment: "Specimen Rejected: Specimen too old for analysis".

 

**Specimen received unspun between 2 - 6 hours from collection will be run and results will be reported with the following comment: "Interpret with caution.  Glucose decreases by ~5.0% per hour and may be significantly falsely decreased for uncentrifuged blood received greater than 2 hours after collection.  The rate of decrease might be greater for patients with elevated white blood counts."

 

**Specimen received unspun greater than 6 hours from collection will be cancelled with the following comment: "Specimen Rejected: Inappropriate Specimen Handling".

Collection Instructions

Collect specimen per standard laboratory collection procedures. 

 

Specimen Handling and Transport Instructions

UCMC Onsite Instructions: 

Collect specimen per standard collection procedure and send to laboratory immediately.  Samples must be received within 2 hours of collection.

 

UCMC Offsite and UC MedLab Outreach Instructions: 

  • Samples must be centrifuged within 30 min of collection.
  • Centrifuge specimens at >2500 x g for 10 minutes at room temperature.
  • Aliquot sample into plastic transport tube containing a minimum of 0.2 mL of specimen.
  • Samples must be sent refrigerated at 2-8oC.

Rejection Criteria

  • Common specimen rejected situations include: incorrect specimen type, insufficient volume, missing or incomplete specimen identifiers, incorrect specimen transport, or specimens outside stability limits. 
  • Specimens that are clotted or grossly hemolyzed.
  • Specimens that were transported unspun/whole blood and draw time is greater than 6 hours.
  • Samples left at room temperature should not be used.

Reference Values

 

Test

Age

Sex

Reference Range

Glucose

All

All

Fasting: 60-99 mg/dL

Non-Fasting: 60 - 139 mg/dL

 

Note: Reference range based on in-house studies, recommendations from Tietz Textbook of Clinical Chemistry, and Roche product literature.  

Critical Values

Analyte

Unit

Low

High

Age

Glucose

mg/dL

<40

>500

>14 days

Glucose

mg/dL

<30

>300

≤ 14 days

Turnaround Time

Turnaround times are relative to the time the specimen is received in the test laboratory. 

 

STAT Turnaround Time: 1 hour

Routine Turnaround Time: 4 hours

Testing Schedule: 24/7

Clinical Indications

Most frequent cause of hyperglycemia is diabetes mellitus resulting from a deficiency in insulin secretion or action. A number of seconday factors also contribute to elevated blood glucose levels. These include pancreatitis, thyroid dysfunction, renal failure and liver disease. Hypoglycemia is less frequently observed. A variety of conditions may cause low blood glucose levels such as insulinoma, hypopituitarism or insluin induced hypoglycemia.

Test Components

Glucose
 

CPT Codes

82947

LOINC Codes

2345-7

Methodology

Enzymatic Method with hexokinase (Roche Diagnostics)

Synonyms/Keyword Search

Sugar

Additional Information

  • Results should always be assessed in conjunction with patient's medical history, clinical examination and other findings.
  • When blood is drawn and permitted to clot and to stand uncentrifuged at room temperature, the average decrease in serum glucose is approximately 7% in one hour (0.28 to 0.56 mmol/L or 5 to 10 mg/dL). This decrease is the result of glycolysis. Glycolysis can be inhibited by collecting the specimen in fluoride tubes.
  • Patients can be fasting or non-fasting.
  • Also included in Basic Metabolic Panel KPNL, Comprehensive Metabolic Panel CPNL, ER Panel I STKG, Renal Function Panel RPNL, CMP for chronic lymphocytic leukemia (CPNL FOR CLL PATIENTS ONLY) SSTCP, BMP for chronic lymphocytic leukemia (KPNL FOR CLL PATIENTS ONLY)  SSTKP

Last Review Date

8/19/2024

Volume

Preferred Volume: 0.5 mL

Minimum Volume: 0.2 mL

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