Glucose, Fasting, Plasma
NY State Approved Indicates the status of NY State approval and if the test is orderable for NY State clients.
Glucose levels are used to diagnose and manage diabetes mellitus and other carbohydrate metabolism disorders including gestational diabetes, neonatal hypoglycemia, idiopathic hypoglycemia, and pancreatic islet cell carcinoma.
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
Glucose, Fasting, P
Fasting Blood Sugar
FBS (Fasting Blood Sugar)
FBS (Fasting Blood Sugar)
Specimen Type Describes the specimen type needed for testing
Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.
Container/Tube: Grey-top (potassium oxalate/sodium fluoride)
Specimen Volume: 1 mL
Collection Instructions: Fasting patient (4 hours or more).
Specimen Minimum Volume Defines the amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.
Yes (Grossly hemolyzed)
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
The most common disease related to carbohydrate metabolism is diabetes mellitus. Insufficient blood levels of active insulin characterize diabetes mellitus. Symptoms include polyuria, abnormally elevated blood and urine glucose values, excessive thirst, constant hunger, sudden weight loss and possibly elevated blood and urine ketones. Complications from diabetes are the third leading cause of death in the US. There are approximately 16 million diabetics in the US and that number is growing. It is estimated that at least 5 million of these people have not been diagnosed. The prevalence in the population age 65 and older is 18.4%, representing 6.3 million cases. The cost of diabetes to the US economy exceeds $92 billion annually.
Over production or excess administration of insulin causes a decrease in blood glucose to levels below normal. In severe cases the resulting extreme hypoglycemia is followed by muscular spasm and loss of consciousness, known as insulin shock.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
0-11 months: not established
> or =1 year: 70-100 mg/dL
Any of the following results, confirmed on a subsequent day, can be considered diagnostic for diabetes:
-fasting plasma or serum glucose > or = 126 mg/dL after an 8-hour fast
-2-hour plasma or serum glucose > or = 200 mg/ dL during a 75-gram oral glucose tolerance test (OGTT)
-random plasma or serum glucose >200 mg/ dL plus typical symptoms.
Patients with "impaired" patients are those whose fasting serum or plasma glucose falls between 110-126 mg/dL or whose 2-hour value on OGTT fall between 140-199 mg/dL. These patients have a markedly increased risk of developing type 2 diabetes and should be counseled for lifestyle changes and followed up with more testing. Indications for screening/testing include strong family history, marked obesity; history with babies over 9 pounds, and recurrent skin and genitourinary infections.
Glucose levels < or = 25 mg/dL in infants <1 week are considered to be potentially life threatening as are glucose levels < or = 40 mg/dL in infants >1 week.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
Once the blood is drawn, the cells in the blood will begin to metabolize the glucose that is present. At room temperature, glucose in the blood will decrease by 10% per hour. Therefore, in a non-gel separator tube, the specimen should be centrifuged as soon as possible and the plasma or serum removed from the cells. If the blood is drawn in a serum or plasma separator tube, the glucose is stable once the sample has been spun and the gel is in place. Inhibitors of glucose metabolism such as fluoride can be used. Glycolysis will take place but at a much reduced rate, approximately 10% over 3 hours.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
Tietz Textbook of Clinical Chemistry. 4th edition. Edited by CA Burtis, ER Ashwood, DE Bruns. WB Saunders Company, Philadelphia, 2006; 5:837-901
Method Description Describes how the test is performed and provides a method-specific reference
Glucose in the serum, in the presence of hexokinase, is converted to glucose-6-phosphate (G-6-P). Glucose-6-phosphate dehydrogenase (G-6-PDH), in the presence of NADP, oxides G-6-P to gluconate-6-phosphate and NADPH. The rate of NADPH formation is directly proportional to glucose concentration in the serum and is measured photometrically. (Roche glucose reagent package insert; Indianapolis, IN, January 2000)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Monday through Saturday
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
Same day/1 day
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location The location of the laboratory that performs the test
Test Classification Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer's instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR), Investigation Use Only (IUO) product, or a Research Use Only (RUO) product.
This test has been cleared or approved by the U.S. Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.
CPT Code Information Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Medical Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
LOINC® Code Information Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the result codes returned for this test or profile.
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