Quantitative determination

موضوع: Quantitative determination 8/4/2008, 19:51

Quantitative determination
Of blood glucose in human serum

Fasting blood sugar (FBS):

Commonly used to screen for disorders of glucose metabolism, mainly diabetes mellitus, the fasting plasma glucose test measures plasma glucose levels following a 12 to14-hour fast. In the fasting state, blood glucose levels, stimulating release of the hormone glucagon. Glucagon then acts to raise plasma glucose by accelerating glycogenolysis, stimulating glyconeogenesis, and inhibiting glycogen synthesis. Normally, secretion of insulin checks this rise in glucose levels. In diabetes, however, absence or deficiency of insulin allows persistently high glucose levels.

Patient preparation:

As appropriate, explain that this test detects disorders of glucose metabolism and aids diagnosis of diabetes. Advise him to fast-taking only water-for 8 to 12 hours before the test. Tell him this requires a blood sample. Withhold drugs that affect test results. If the patient is known to have diabetes, blood should be drawn before administration of insulin or oral hypoglycemic drugs.

ü Clinical alert: Alert the patient to the symptoms of hypoglycemia – weakness, restlessness, nervousness, hunger and sweating – and till him to report such symptoms immediately.

Values: Normal range for fasting blood glucose varies according to the laboratory procedure. Generally, normal values after an 8 to 12-hour fast are follows:

Fasting serum: 70 to 100 mg/dl.

Fasting whole blood: 60 to 100 mg/dl.

Non-fasting: 85 to 125 mg/dl in persons over age 50.

70 to 115 mg/dl in persons under age 50.

Implications of results:

Fasting blood glucose levels of 140 to 150mg/dl or higher, obtained on two or more occasions may be considered diagnostic of diabetes mellitus if possible causes of hyperglycemia have been ruled out.

Non-fasting levels that exceed 200mg/dl also suggest diabetes.

Note that: Depressed glucose levels can result from hyperinsulinism “overdose of insulin is the most common cause”.

Two-hour postprandial blood sugar:

The two-hour postprandial plasma glucose test reflects metabolic response to a carbohydrate challenge:

Normally, blood glucose returns to the fasting level within 2 hours. This test, performed on a blood specimen taken after a meal, is used to monitor therapy and to confirm diabetes in a patient with borderline fasting blood glucose levels.

Patient preparation:

Explain to the patient that this test evaluates glucose metabolism and helps detect diabetes. The patient should observe an overnight fast (allowing water only) followed by a high carbohydrate breakfast (including milk, orange juice, cereal with sugar, and toast). The patient should avoid smoking and strenuous exercise after the meal. Tell the patient this test requires a blood sample, which will be drawn 2-hours after the meal.

Value: Normal glucose values are less than 120mg/dl.

Implications of results:

Values above 140mg/dl are abnormal in adults under age 50.

Values above 160mg/dl are abnormal in persons over age 60.The speed of glucose clearance declines with advancing age and levels may raise an average of 6mg/dl for each decade over age 30.

High glucose levels may also occur with pancreatitis, uncontrolled diabetes mellitus.
Depressed glucose levels occur in hyperinsulinism

موضوع: رد: Quantitative determination 8/4/2008, 20:11

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