Name = PAGENAME
DiseasesDB = 29485
ICD9 = ICD9|276.2
MeshID = D007662
ɪs) is a state in metabolismoccurring when the liverexcessively converts fat into fatty acids and ketone bodieswhich can be used by the body for energy.
Adiposetissue consists of highly specialized cells which store energy in the form of a triglyceride and release it upon hydrolysisin a process known as lipolysis, yielding three fatty acidsand one glycerol molecule. [Citation | title=Developing A More Sensitive Assay To Analyze Fatty Acid Release From Human Fat Cells: Preliminary Studies. | newspaper=University of Maryland School of Medicine | pages=18 | date=August 5 2005 | url=http://medschool.umaryland.edu/OSR/docs/ForumBooklet/2005.pdf ] These ketone bodiesare a by-product of the lipid metabolic pathway after the fat is converted to energy. [Citation | title=http://www.jhu.edu/~jhumag/495web/fat.html | newspaper= Johns Hopkins University| url=http://www.jhu.edu/~jhumag/495web/fat.html ] [Citation | title=http://www.med.upenn.edu/nutrimed/MedNutandDisSampleCase.shtml | newspaper= University of Pennsylvania School of Medicine| url=http://www.med.upenn.edu/nutrimed/MedNutandDisSampleCase.shtml] [Citation | title=http://www.med.umich.edu/diabetes/patients/dictionary.htm | newspaper=University of Michigan Medical School | url=http://www.med.umich.edu/diabetes/patients/dictionary.htm] [Citation | title=http://www.orcbs.msu.edu/occupational/programs_guidelines/right_to_know/gloss/ketosis.htm | newspaper= Michigan State University| url=http://www.orcbs.msu.edu/occupational/programs_guidelines/right_to_know/gloss/ketosis.htm] [Citation | title=http://depts.washington.edu/chdd/outlook/outlook00_13.1.pdf | newspaper= University of Washington School of Medicine| url=http://depts.washington.edu/chdd/outlook/outlook00_13.1.pdf] Ketoacidosis, by contrast, is the accumulation of excessive keto acids in the blood stream (specifically acetoacetateand beta-hydroxy butyrate).
Most medical resources regard ketosis as a physiological state associated with chronic
starvation.Fact|date=November 2007 Glucose is regarded as the preferred energy source for all cells in the body with ketosis being regarded as a crisis reaction of the body to a lack of carbohydrates in the diet. In recent years this viewpoint, both the body's preference for glucose and the dangers associated with ketosis, has been challenged by some doctors. [cite journal|last=Eaton|first=S. Boyd|coauthors=Melvin Konner|year=1985|title=Paleolithic nutrition: a consideration of its nature and current implications|journal=New England Journal of Medicine|volume=312|pages=283–89|url=http://content.nejm.org/cgi/content/citation/312/5/283|pmid=2981409] [Eades, M. et al. "Protein Power Lifeplan" [http://www.proteinpower.com] ] [cite journal | author= William S Yancy, Jr, Marjorie Foy, Allison M Chalecki, Mary C Vernon, and Eric C Westman | title=A low-carbohydrate, ketogenic diet to treat type 2 diabetes | journal=Journal of Nutrition and Metabolism | year=2005 | volume=2 | doi= 10.1186/1743-7075-2-34 | pages=34] Ketone bodies, from the breakdown of fatty acids to acetyl groups, are also produced during this state, and are burned throughout the body. Excess ketone bodies will slowly decarboxylate into acetone. That molecule is excreted in the breathand urine.When glycogenstores are not available in the cells (glycogen is primarily created when carbohydratessuch as starchand sugarare consumed in the diet), fat ( triacylglycerol) is cleaved to give 3 fatty acid chains and 1 glycerolmolecule in a process called lipolysis. Most of the body is able to utilize fatty acids as an alternative source of energy in a process where fatty acid chains are cleaved to form acetyl-CoA, which can then be fed into the Krebs Cycle. It is important to note that acetyl-CoA can only enter the Krebs Cycle bound to oxaloacetate. When carbohydrate supplies are inadequate, however, the body naturally converts oxaloacetate to glucose for use by the brain and other tissues. When acetyl CoA does not bind with oxaloacetate, the liver converts it to ketones (or ketone bodies). If these ketones are not used for fuel by muscles, nerves, or the brain, they begin to accumulate and ultimately lead to a condition known as ketosis. During this process a high concentration of glucagonis present in the serum and this inactivates hexokinaseand phosphofructokinase-1(regulators of glycolysis) indirectly, causing most cells in the body to use fatty acids as their primary energy source. At the same time, glucoseis synthesized in the liver from lactic acid, glucogenic amino acids, and glycerol, in a process called gluconeogenesis. Glucose is a simple sugar made by the body and is necessary for proper bodily function. This glucose is used exclusively for energy by cells such as neuronsand red blood cells.Fact|date=February 2007
Ketosis should not be confused with
ketoacidosis(diabetic ketoacidosis or the less common alcoholic ketoacidosis), which is severe ketosis causing the pH of the blood to drop below 7.2. Ketoacidosis is a medical condition usually caused by diabetesand accompanied by dehydration, hyperglycemia, ketonuria and increased levels of glucagon. The high glucagon, low insulin serum levels signals the body to produce more glucose via gluconeogenesisand glycogenolysis, and ketone bodies via ketogenesis. High levels of glucose causes the failure of tubular reabsorption in the kidneys, causing water to leak into the tubules in a process called osmotic diuresis, causing dehydration and further exacerbating the acidosis.
If the diet is changed from a highly glycemic diet to a diet that does not substantially contribute to
blood glucose, the body goes through a set of stages to enter ketosis. During the initial stages of this process the adult brain does not burn ketones, however the brain makes immediate use of this important substrate for lipid synthesis in the brain. After about 48 hours of this process, the brain starts burning ketones in order to more directly utilize the energy from the fat stores that are being depended upon, and to reserve the glucose only for its absolute needs, thus avoiding the depletion of the body's protein store in the muscles.
Whether ketosis takes place can be checked by using special urine test strips such as "
Deliberately induced ketosis through a
low-carbohydrate diethas been used to treat medical conditions although most such treatments remain controversial. [G.D Foster et al, NEJM2003;348:2082-90 [http://content.nejm.org/cgi/content/abstract/348/21/2082] ] [Bravata et al., "Efficacy and safety of low-carbohydrate diets: a systematic review." Journal of the American Medical Association, Apr, 2003; 289(14):1837-50 [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12684364&dopt=Abstract] ]
* [http://www.emedicine.com/emerg/topic135.htm Diabetic Ketoacidosis]
* [http://www.nhsdirect.nhs.uk/articles/article.aspx?articleId=221 NHS Direct: Ketosis]
* [http://www.ajcn.org/cgi/content/full/76/1/65 Breath acetone is a reliable indicator of ketosis in adults consuming ketogenic meals] , American Journal of Clinical Nutrition.
* The Merck Manual - : [http://www.merck.com/mrkshared/mmanual/section2/chapter13/13b.jsp Diabetic Ketoacidosis] : [http://www.merck.com/mrkshared/mmanual/section2/chapter13/13c.jsp Alcoholic Ketoacidosis]
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Look at other dictionaries:
ketosis — 1900, from keto , comb. form of KETONE (Cf. ketone), + OSIS (Cf. osis) … Etymology dictionary
ketosis — [kē tō′sis] n. [ModL < KET(O) + OSIS] a condition in which there is excessive formation of ketones in the body … English World dictionary
ketosis — /ki toh sis/, n. Pathol. the accumulation of excessive ketones in the body, as in diabetic acidosis. [1915 20; KET + OSIS] * * * ▪ pathology metabolic disorder marked by high levels of ketones in the tissues and body fluids, including blood … Universalium
ketosis — A condition characterized by the enhanced production of ketone bodies, as in diabetes mellitus or starvation. [ketone + osis, condition] bovine k. a common metabolic disease of cows which appears as a rule within a few weeks after parturition … Medical dictionary
ketosis — n. raised levels of ketone bodies in the body tissues. Ketone bodies are normal products of fat metabolism and can be oxidized to produce energy. Elevated levels arise when there is an imbalance in fat metabolism, such as occurs in diabetes… … The new mediacal dictionary
ketosis — noun Etymology: New Latin Date: 1917 an abnormal increase of ketone bodies in the body • ketotic adjective … New Collegiate Dictionary
ketosis — Metabolic production of abnormal amounts of ketones. A consequence of diabetes mellitus … Dictionary of molecular biology
ketosis — noun A metabolic state in which the body produces ketones to be used as fuel by some organs so that glycogen can be reserved for organs that depend on it. This condition occurs during times of fasting, starvation, or while on a ketogenic weight… … Wiktionary
ketosis — n. disorder causing overproduction of ketones in the body (Medicine) … English contemporary dictionary
ketosis — [kɪ təʊsɪs] noun Medicine a condition characterized by raised levels of ketone bodies in the body, associated with abnormal fat metabolism and diabetes mellitus. Derivatives ketotic adjective … English new terms dictionary