Mayo Test Catalog, (Sorted By Test Name) - Mayo Medical ...

RGLUR
89847
mellitus which is characterized by insufficient blood levels of active insulin. 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 United States. There are approximately 16 million diabetics in the United
States, 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. Overproduction 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.
Useful For: Diagnosing and managing diabetes mellitus and other carbohydrate metabolism disorders
including gestational diabetes, neonatal hypoglycemia, idiopathic hypoglycemia, and pancreatic islet cell
carcinoma.
Interpretation: Any of the following results, confirmed on a subsequent day, can be considered
diagnostic for diabetes: -a 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 glucose >200 mg/dL, plus typical symptoms. Patients with "impaired" glucose regulation are
those whose fasting serum or plasma glucose fall between 101 and 126 mg/dL, or whose 2-hour value on
OGTT fall between 140 and 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 and testing include strong family history, marked obesity, history of babies over 9 pounds,
and recurrent skin and genitourinary infections. Glucose levels < or =25 mg/dL in infants 1 week.
Glucose levels > or =400 mg/dL are considered a critical value.
Reference Values:
0-11 months: not established
> or =1 year: 70-140 mg/dL
Clinical References: Tietz Textbook of Clinical Chemistry. 4th edition. Edited by CA Burtis, ER
Ashwood, DE Bruns. WB Saunders Company, Philadelphia, 2006, 25:837-907
Glucose, Random, Urine
Clinical Information: 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 (as seen with diabetes mellitus) may result in an
increase in filtered load of glucose and may overwhelm the tubules' reabsorptive capacity resulting in
glucosuria. Glucosuria occurs when the renal threshold for glucose is exceeded (typically >180 mg/dL).
This is most commonly, although not exclusively, seen in diabetes. 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 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.
Useful For: An indicator of abnormal proximal tubule function Limited usefulness in the screening or
management of diabetes mellitus
Interpretation: 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).
Reference Values:
< or =15 mg/dL
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