glucose in body fluid
Reference interval
- Male & Female: 70-110 mg/dL (serum), 40-80 mg/dL (CSF) 3.9-6.1 mmol/L (serum), 2.8-4.4 mmol/L (CSF) conversion factor = 0.5551
Principle
The Kodak Ektachem Clinical Chemistry Slide (GLU) is a dry, multilayered analytical element coated on a clear polyester support.
A 10 uL drop of patient sample is deposited on the slide where the spreading layer promotes the uniform distribution of the sample and permits an even penetration of solute molecules into the underlying reagent layer. The oxidation of sample glucose is catalyzed by glucose oxidase to form hydrogen peroxide & gluconate. This reaction is followed by an oxidative coupling catalyzed by peroxidase in the presence of chromogens to produce a dye.
The intensity of the dye is measured by reflected light. The chemistry of the glucose slides has been described by Curme, et al (1978).
Of the many known assays for determining glucose, those enzymatically linked are highly rated for their specificity, speed, sensitivity, & precision. Although glucose oxidase is highly specific for beta-D-glucose, peroxidase is not specific because the color coupling reactions may be interfered with by uric acid, ascorbic acid, & other reducing agents. These substances are minor interferences, however, because their particular color-forming reaction used in the assay competes successfully for the peroxide. Moreover, the spreading layer is designed to screen the assay from such common interference as serum proteins, hemoglobin & bilirubin.
Clinical significance
Glucose is the primary cellular energy source. Fasting plasma glucose concentrations & tolerance to a dose of glucose are used to establish the diagnosis of diabetes mellitus & disorders of carbohydrate metabolism. Plasma glucose is used to monitor therapy in diabetics & in patients with dehydration, coma, hypoglycemia, insulinoma, acidosis, & ketoacidosis.
Increases
- pharmaceutical agents:
- in vivo effects
- chemical interferences
- acetaminophen, aminoaalicyclic acid, ascorbate, dextran, hydralazine, isoproterenol, L-dopa, mercaptopurine, methimazole, methyldopa, nalidixic acid, oxazepam, propylthiouracil
Decreases
- pharmaceutical agents:
- in vivo effects
Specimen
No special patient preparation is required.
Collect the specimen by standard venipuncture technique. Remove serum promptly from the clot to avoid metabolism of glucose by the cells (approximately 7% per hour at room temperature). A maximum of 30 minutes between drawing & separation from the clot is recommended.
Urine: Collect urine specimens by standard laboratory procedures. Urine preservatives are not necessary & may interfere. Refrigerate specimens during collection & keep refrigerated until analysis.
Cerebrospinal fluid (CSF): Collect cerebrospinal fluid specimens by standard laboratory procedures. Hemolyzed specimens should not be used. Freeze specimen if not analyzed immediately. CSF specimens are sometime contaminated with bacteria & other cellular constituents that lower the concentration of glucose with time.
Minimum sample required is 0.5 milliliter with an optimum size of 1.0 milliliter or larger.
Interferences
- Preliminary data indicated that hemolysis does interfere with this method.
- Total Protein less than 5 g/dL may cause a decrease of up to 5% of the actual value. TP greater than 10 g/dL may cause an apparent increase of 5 to 6% at normal glucose levels.
- Particulate matter (e.g. fibrin) in sufficient quantity may coat the spreading layer & limit diffusion of oxygen causing a negative interference. Do not centrifuge serum samples before clotting is complete.
- Elevated lipids may limit diffusion of oxygen to the reactants. Dilute grossly lipemic samples two-fold before analysis.
- Ascorbic Acid used in urine can cause a decrease in the glucose result approximately equal to the ascorbate concentration.
More general terms
More specific terms
- glucose in amniotic fluid
- glucose in body fluid fasting
- glucose in CSF
- glucose in serum/plasma
- glucose in serum/plasma/blood
- glucose in stool
- glucose in urine
Additional terms
References
- ↑ Kodak Ektachem 700 Analyzer Operator's Manual, Kodak Clinical Products, Rochester, New York.
- ↑ Kodak Ektachem Slide Package Inserts, Kodak Clinical Products Rochester, New York.
- ↑ Kodak Ektachem Training Manual, Kodak Clinical Products, Rochester, New York.
- ↑ Clinical Diagnosis & Management by Laboratory Methods, 19th edition, J.B. Henry (ed), W.B. Saunders Co., Philadelphia, PA. 1996, pg 11.
- ↑ Glucose, Body Fluid Laboratory Test Directory ARUP: http://www.aruplab.com/guides/ug/tests/0020503.jsp