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Test ID: HYPOG    
Hypoglycemic Agent Screen, Serum

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

Evaluation of suspected insulinoma characterized by hypoglycemia and increased plasma insulin concentration.

 

Detecting drugs that stimulate insulin secretion

 

If hypoglycemia is the result of 1 of these drugs, the test will detect the drug at physiologically significant concentrations in serum during an episode of hypoglycemia.

 

Drugs detected by this procedure are:

-The first-generation sulfonylureas-acetohexamide, chlorpropamide, tolazamide, and tolbutamide

-The second-generation sulfonylureas--glimepiride, glipizide, and glyburide

-The meglitinide-repaglinide

 

Drugs designed to make tissues more sensitive to insulin that do not induce hypoglycemia, such as pioglitazone, rosiglitazone, and troglitazone (recently withdrawn from the United States market) are not included in this screen test.

 

Drugs that lower blood glucose through mechanisms not related to stimulation of insulin secretion, such as acarbose, metformin, and miglitol are not included in this screen test.

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

The metabolic and hormonal profiles of insulinoma and sulfonylurea-induced hypoglycemia are identical. Therefore, in the evaluation of the hypoglycemic patient, the possible use of oral hypoglycemic agents as the cause for low blood glucose and elevated plasma insulin must be considered. Absence of hypoglycemic drugs in blood serum during an episode of low blood glucose should be demonstrated before considering pancreatic exploration for suspected insulinoma.

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.

ACETOHEXAMIDE

Negative: <1,000 ng/mL

 

CHLORPROPAMIDE

Negative: <1,000 ng/mL

 

TOLAZAMIDE

Negative: <20 ng/mL

 

TOLBUTAMIDE

Negative: <50 ng/mL

 

GLIMEPIRIDE

Negative: <20 ng/mL

 

GLIPIZIDE

Negative: <3 ng/mL

 

GLYBURIDE

Negative: <3 ng/mL

 

REPAGLINIDE

Negative: <3 ng/mL

Note: The report indicates a specific drug is positive if that drug is detected at a concentration greater than the sensitivity limit. The test sensitivity limit listed for each drug is lower than the concentration that will cause increased insulin and decreased glucose.

Interpretation Provides information to assist in interpretation of the test results

Use of hypoglycemic agents outside of the context of treatment of type 2 diabetes is likely to cause hypoglycemia associated with elevated plasma insulin. Patients presenting with hypoglycemia due to ingestion of a first-, second-, or third-generation hypoglycemic agent will have drug present in serum greater than the minimum effective concentration (see Reference Values). Presence of drug indicates that the patient has recently ingested a hypoglycemic agent.

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

Proper interpretation requires that the blood specimen be drawn during or close to the time of a hypoglycemic episode. Drugs will not be detected (and are not likely to be present) if blood is drawn when blood glucose is normal in nondiabetic patients.

 

All drugs that stimulate insulin secretion undergo extensive metabolism before excretion. The parent drug is therefore not present in urine. Blood serum is the specimen of choice for detecting use of the hypoglycemic drugs: urine or plasma is not an acceptable specimen.

 

This test is not intended for therapeutic drug monitoring.

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

Ben-Ami H, Nagachandran P, Mendelson A, Edoute Y: Drug-induced hypoglycemic coma in 102 diabetic patients. Arch Int Med 1999;159:281-284