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Test ID: GLUR    
Glucose, 24 Hour, Urine

Useful For Suggests clinical disorders or settings where the test may be helpful

Limited usefulness in the screening or management of diabetes mellitus

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Under normal circumstances, glucose is readily filtered by glomeruli and the filtered glucose is reabsorbed by the proximal tubule; essentially no glucose is normally excreted in the urine. However, the capacity for the proximal tubule to reabsorb glucose is limited; if the filtered load exceeds the proximal tubule's reabsorptive capacity, a portion of the filtered glucose will be excreted in the urine. Thus, elevated serum glucose concentrations (such as occur with diabetes mellitus) may result in an increase in filtered load of glucose and may overwhelm the tubules' reabsorptive capacity resulting in glucosuria.

 

Additionally, conditions which adversely affect proximal tubule function may also result in decreased reabsorption of glucose, and increased urinary glucose concentration, even in the presence of normal plasma glucose concentrations. Some of these conditions include Fanconi syndrome, Wilson's disease, hereditary glucosuria, and interstitial nephritis. These conditions are relatively rare, and most causes for elevated urine glucose concentrations are due to elevated serum glucose levels.

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.

< or =0.15 g/specimen

Interpretation Provides information to assist in interpretation of the test results

Elevated urine glucose concentration reflects either the presence of hyperglycemia or a defect in proximal tubule function.

 

As a screening test for diabetes mellitus, urine glucose testing has a low sensitivity (though reasonably good specificity).

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Urine glucose monitoring for the management of diabetes mellitus has essentially been replaced by more accurate and reliable blood glucose determinations.

Clinical Reference Provides recommendations for further in-depth reading of a clinical nature

Tietz Textbook of Clinical Chemistry. Edited by CA Burtis, ER Ashwood. Third edition, Philadelphia, PA. WB Saunders Company, 1999

Special Instructions and Forms Describes specimen collection and preparation information, test algorithms, and other information pertinent to test. Also includes pertinent information and consent forms to be used when requesting a particular test