ketone bodies in body fluid

Indications: 1) assessment of diabetic ketoacidosis 2) verification of compliance with weight-reducing regimen Normal range: 1) serum: < 1 mg/dL (0.1 mmol/L) with overnight fast 2) urine: negative, limit of detection 5-10 mg/dL (0.5-1.0 mmol/L) Increases: 1) chemical interferences a) serum -> aspirin intoxication, IV ethanol, levodopa (Ketostix) streptozocin, insulin (prolonged, excessive) b) urine (in vitro) -> acetylcysteine, captopril, cysteine, dimercaprol (BAL), 8-hydroxyquinoline (preservative), levodopa, MESNA (2-mercaptoethane sulfonate), D-penicillamine, phenazopyridine, phenolphthalein, phenylketones c) urine (in vivo) -> aspirin intoxication, ethanol, ether anesthesia, inositol, isopropanol, metformin, methionine, nicotinic acid, phenformin, valproic acid d) hemolysis causes discoloration of test tablets or sticks 2) clinical disorders a) diabetic ketoacidosis*, prolonged fasting, severe carbohydrate restriction with normal fat intake (weight- reducing diets), anorexia nervosa, persistent vomiting, glycogen storage diseases, branched chain ketonuria, methylmalonic aciduria, exercise in untrained subjects, pregnancy, stress, post-anesthesia b) states with markedly increased metabolic rates -> high fever, severe thyrotoxicosis, active acromegaly c) excessive hormone production/administration -> growth hormone, ACTH, glucocorticoids, hyperinsulinism, catecholamines * in some cases of diabetes mellitus with elevated blood ketone levels, no ketone bodies appear in the urine. Method: - reagent strip: nitroprusside (Miles Inc. Acetotest, Ketostix, Labstix, Multistix, BMC Chemstrip) - beta-hydroxybutyrate is NOT measured - acetone is measured by Chemstrip & Acetest Specimen: 1) serum or plasma 2) cover, deliver to laboratory immediately 3) refrigerate until analysis (within 5 days) 4) avoid hemolysis Interferences: False positives (urine): 1) highly pigmented urine 2) specimens with 8-hydroxquinoline as a preservative Two methods may be used to distinguish false positive results caused by free sulfhydryl groups from true positives: 1) add 1 drop of glacial acetic acid to the test pad -> color is removed from false positives 2) monitor reaction constantly a) true positive develop a purple color with Acetest that continues to intensify for 60 seconds b) false positives develop a purple color which fades within 30 seconds

Related

acetoacetate in serum/plasma acetoacetate; beta-ketobutyrate; 3-ketobutyrate beta(3)-hydroxybutyrate in blood/plasma/serum

Specific

ketone bodies in blood ketone bodies in serum/plasma ketone bodies in urine ketone bodies in urine post glucose ketone bodies in vitreous fluid

References

Clinical Guide to Laboratory Tests, 3rd ed. Teitz ed., W.B. Saunders, 1995