|
Principle: The test is based on the principle of Legal`s test. Acetoacetic acid and acetone form a violet coloured complex with sodium nitroprusside in alkaline medium.
Evaluation: Acetoacetic acid reacts more sensitively than acetone. Values of 10 mg/dl of acetoacetic acid or 50 mg/dl acetone are indicated. The colour fields correspond to the following acetoacetic acid values:
0 (negative), 25 (+), 100 (++) and 300 (+++) mg/dl or
0 (negative)5 2.5 (+), 10 (++) and 30 (+++) mmol/l.
Phenylketones in higher concentrations interfere with the test, and will produce deviating colours. ß-hydroxybutyric acid (not a ketone) is not detected. Phthalein compounds interfere by producing a red colouration.
Diagnosis: Ketone bodies including acetoacetic acid, acetone, and ß-hydroxybutyric acid are only produced in the liver. Ketones in the urine are caused by an abnormal carbohydrate metabolism. Frequently, ketonuria is a sign of diabetic ketosis, which in connection with other metabolic abnormalities may cause diabetic coma. Ketonuria may also be noted in case of insulin overdoses, starvation (e.g. slimming diet, calorie free diet), dangerous metabolic abnormalities during pregnancy (Hyperemesis gravidarum), acetonemic vomiting of infants and fever caused especially by infections.
|