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Ketones 

  • Author: Bishnu Prasad Devkota, MD, MHI, FRCS(Edin), FRCS(Glasg), FACP; Chief Editor: Eric B Staros, MD  more...
 
Updated: Oct 30, 2015
 

Reference Range

Acetoacetate, beta-hydroxybutyrate, and acetone are ketone bodies. In carbohydrate-deficient states, fatty-acid metabolism spurs acetoacetate accumulation. The reduction of acetoacetate in the mitochondria results in beta-hydroxybutyrate production. Beta-hydroxybutyrate and acetoacetate, the predominant ketone bodies, are rich in energy. Beta-hydroxybutyrate and acetoacetate transport energy from the liver to other tissues.

Acetone forms from the spontaneous decarboxylation of acetoacetate. Acetone is the cause of the sweet odor on the breath in persons with ketoacidosis.[1, 2] Ketone bodies fuel the brain with an alternative source of energy (close to two thirds of its needs) during periods of prolonged fasting or starvation, when the brain cannot use fatty acids for energy.

The reference range for ketone is a negative value, at less than 1 mg/dL (< 0.1 mmol/L).[3]

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Interpretation

The following conditions increase ketone values:

The following conditions spur false-positive results[4, 5] :

  • Some Parkinson medications
  • Stimulant laxative (eg, Ex-Lax)
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Collection and Panels

Collection details are as follows:

  • Yellow tube for serum ketones
  • Urinalysis test strips to detect ketonuria

Panels are as follows:

  • Serum ketones
  • Urinalysis
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Background

Description

Acetoacetate, beta-hydroxybutyrate, and acetone are ketone bodies. In carbohydrate-deficient states, fatty-acid metabolism spurs acetoacetate accumulation. The reduction of acetoacetate in the mitochondria results in beta-hydroxybutyrate production. Beta-hydroxybutyrate and acetoacetate, the predominant ketone bodies, are rich in energy. Beta-hydroxybutyrate and acetoacetate transport energy from the liver to other tissues.

Acetone forms from the spontaneous decarboxylation of acetoacetate. Acetone is the cause of the sweet odor on the breath in persons with ketoacidosis. Ketone bodies fuel the brain with an alternative source of energy (close to two thirds of its needs) during periods of prolonged fasting or starvation, when the brain cannot use fatty acids for energy.

Although ketones are omnipresent in the blood (< 1 mg/dL), levels increase during periods of fasting and prolonged exercise.[4] The nitroprusside test only detects acetoacetate in blood and urine; however, it does not assess beta-hydroxybutyrate, the most accurate indicator of ketone body levels. The nitroprusside test is only a semiquantitative assessment that is associated with false-positive results.[4]

Beta-hydroxybutyrate, acetoacetate, and acetone are endogenous ketone bodies. Note, however, that beta-hydroxybutyrate is not technically a ketone; it is a carboxylic acid.[4] Tissues outside the liver transfer coenzyme A from succinylcoenzyme A to acetoacetate, and, via the citric acid cycle, metabolize the active acetoacetate to carbon dioxide and water. Similarly, ketone bodies are metabolized using other pathways. Acetone discharge occurs in expired air and in urine.[6] Ketonuria ensues in actual or functional carbohydrate-deficient states when metabolism switches from using carbohydrates to using fat to produce energy. These states can include uncontrolled diabetes mellitus, insufficient intake of carbohydrates owing to starvation or weight reduction, pregnancy, or vomiting.[7]

In normal states, ketones are not present in the urine. However, increased urinary ketone levels may occur with fasting, in postexercise states, and in pregnancy. In individuals with diabetes, urinary ketone levels are often increased before an elevation occurs in the serum.[8, 9] Dehydration and the presence of levodopa metabolites, mesna (sodium mercaptoethanesulfonate), and other sulfhydryl-containing compounds may cause false-positive testing results.[8]

Serum ketone testing measures acetoacetate; acetone is weakly reactive and beta-hydroxybutyrate is not detected at all. In alcoholic ketoacidosis, initial ketone values may be low or results may be negative. However, with recovery, acetoacetate increases and assay results become positive.[10] The elevated anion gap (see the Anion Gap calculator) found in alcoholic ketoacidosis is primarily due to beta-hydroxybutyrate.[11, 12]

Indications

See the list below:

Considerations

Urinary acetoacetate and breath acetone assessments are good predictors of ketosis. Breath acetone analysis is a noninvasive test and is usually associated with minimal patient discomfort. It can also be used to monitor the efficacy of therapeutic diets (eg, epilepsy patients on ketogenic diets, as ketones are indicators of ketosis).[13] Hypoglycemia in the presence of urinary ketones suggests organic acidemias; however, hypoglycemia in the absence of urinary ketones may be seen in a fatty-acid defect.[14]

The pathological conditions most commonly associated with ketosis are as follows:[4]

  • Diabetic ketoacidosis
  • Alcoholic ketoacidosis (withdrawal following binge drinking)
  • Salicylate overdose
  • Isopropyl alcohol ingestion
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Contributor Information and Disclosures
Author

Bishnu Prasad Devkota, MD, MHI, FRCS(Edin), FRCS(Glasg), FACP Associate Professor of Medicine, St Louis University School of Medicine

Bishnu Prasad Devkota, MD, MHI, FRCS(Edin), FRCS(Glasg), FACP is a member of the following medical societies: American College of Physicians, American Medical Informatics Association, Royal College of Physicians and Surgeons of Glasgow, Royal College of Surgeons of Edinburgh, Healthcare Information and Management Systems Society

Disclosure: Nothing to disclose.

Chief Editor

Eric B Staros, MD Associate Professor of Pathology, St Louis University School of Medicine; Director of Clinical Laboratories, Director of Cytopathology, Department of Pathology, St Louis University Hospital

Eric B Staros, MD is a member of the following medical societies: American Medical Association, American Society for Clinical Pathology, College of American Pathologists, Association for Molecular Pathology

Disclosure: Nothing to disclose.

References
  1. Qiao Y, Gao Z, Liu Y, Cheng Y, Yu M, Zhao L, et al. Breath ketone testing: a new biomarker for diagnosis and therapeutic monitoring of diabetic ketosis. Biomed Res Int. 2014. 2014:869186. [Medline].

  2. Blaikie TP, Edge JA, Hancock G, Lunn D, Megson C, Peverall R, et al. Comparison of breath gases, including acetone, with blood glucose and blood ketones in children and adolescents with type 1 diabetes. J Breath Res. 2014 Nov 25. 8 (4):046010. [Medline].

  3. Wu AHB. Tietz clinical guide to laboratory tests. 4th ed. St. Louis, Mo: Saunders/Elsevier; 2006.

  4. Laffel L. Ketone bodies: a review of physiology, pathophysiology and application of monitoring to diabetes. Diabetes Metab Res Rev. 1999 Nov-Dec. 15(6):412-26. [Medline].

  5. Gomella LG HS. Laboratory Diagnosis: Chemistry, Immunology, Serology. Gomella LG HS, ed. Clinician's Pocket Reference: The Scut Monkey. 11 ed. New York: McGraw-Hill; 2007.

  6. Barrett KE BS, Boitano S, Brooks H. General Principles & Energy Production in Medical Physiology. Barrett KE BS, Boitano S, Brooks H, ed. Ganong's Review of Medical Physiology. 23 ed. New York: McGraw-Hill; 2010.

  7. Williamson MA, Snyder LM, Wallach JB. Wallach's interpretation of diagnostic tests. 9th ed. Wolters Kluwer/Lippincott Williams & Wilkins Health: Philadelphia; 2011.

  8. Meng MV SM, Walsh TJ. Urologic Disorders. McPhee SJ PM, Rabow MW, ed. CURRENT Medical Diagnosis & Treatment. New York McGraw-Hill: 2012.

  9. Ceriotti F, Kaczmarek E, Guerra E, Mastrantonio F, Lucarelli F, Valgimigli F, et al. Comparative performance assessment of point-of-care testing devices for measuring glucose and ketones at the patient bedside. J Diabetes Sci Technol. 2015 Mar. 9 (2):268-77. [Medline].

  10. McGuire LC, Cruickshank AM, Munro PT. Alcoholic ketoacidosis. Emerg Med J. 2006 Jun. 23(6):417-20. [Medline].

  11. Wrenn KD, Slovis CM, Minion GE, Rutkowski R. The syndrome of alcoholic ketoacidosis. Am J Med. 1991 Aug. 91(2):119-28. [Medline].

  12. Woods WA PD. Alcoholic Ketoacidosis. Tintinalli JE SJ, Cline DM, Ma OJ, Cydulka RK, Meckler GD, ed. Tintinalli's Emergency Medicine: A Comprehensive Study Guide. 7th ed. New York McGraw-Hill: 2011.

  13. Musa-Veloso K, Likhodii SS, Cunnane SC. Breath acetone is a reliable indicator of ketosis in adults consuming ketogenic meals. Am J Clin Nutr. 2002 Jul. 76(1):65-70. [Medline].

  14. Qureshi N A-MM, Kentab OY. Hypoglycemia and Metabolic Emergencies in Infants and Children. Tintinalli JE SJ, Cline DM, Ma OJ, Cydulka RK, Meckler GD, ed. Tintinalli's Emergency Medicine: A Comprehensive Study Guide. 7th ed. New York McGraw-Hill: 2011.

  15. Lees MJ, Easley KJ, Sutherland RJ, Yovich JV, Klein KT, Bolton JR. Subcutaneous rupture of the urachus, its diagnosis and surgical management in three foals. Equine Vet J. 1989 Nov. 21 (6):462-4. [Medline].

 
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