metabolism of ketone bodies
TRANSCRIPT
Metabolism of ketone bodies
DR.J.SIVAKUMARASSISTANT PROFESSOR
Carbohydrates are essential for the metabolism of fat.
The acetyl CoA formed from fatty acids can enter and get oxidized in TCA cycle only when carbohydrates are available.
During starvation and diabetes mellitus, acetyl CoA takes the alternate route of formation of ketone bodies.
INTRODUCTION
primary ketone body-Acetoacetate Secondary ketone bodies-beta-hydroxy
butyrate and acetone Site-liver ,mitochondria
Ketone bodies
Ketogenesis
The ketone bodies are formed in the liver; but they are utilized by extra hepatic tissues.
The heart muscle and renal cortex prefer the ketone bodies to glucose as fuel.
Tissues like skeletal muscle and brain can also utilize the ketone bodies as alternate sources of energy, if glucose is not available.
Ketolysis
Organs which can use ketonebodies-placenta, Intestinal mucosal cells, brain and adipocytes.
Almost all tissues and cell types can use ketone bodies as fuel, with the exception of liver and RBC.
Contd..
KETOSIS
Utilization of ketone bodies
when the rate of synthesis exceeds the ability of extrahepatic tissues to utilize them, there will be accumulation of ketone bodies in blood.
This leads to ketonemia, excretion in urine (ketonuria) and smell of acetone in breath.
All these three together constitute the condition known as ketosis.
Contd..
Two important hormones-INSULIN and GLUCAGON.
Regulated at three levels
KETOGENESIS
Regulation
Diabetes mellitus Starvation The brain derives 75% of energy from
ketone bodies under conditions of fasting. Hyperemesis (vomiting) in early pregnancy
may also lead to starvation-like condition and may lead to ketosis.
CAUSES
METABOLIC ACIDOSIS KUSSMAUL’s respiration Smell of acetone OSMOTIC diuresis Dehydration Coma
Clinical features
ROTHERA’S test Serum elecrolytes ACID_BASE parameters GLUCOSE urea
Diagnosis of ketosis
Saturate 5 mL of urine with solid ammonium sulfate.
Add a few drops of freshly prepared sodium nitroprusside followed by 2 mL of liquor ammonia along the sides of the test tube.
Development of a purple ring indicates the presence of ketone bodies in urine
ROTHERA’S test
ROTHERA’s TEST
The most important cause is type 2 DM. intercurrent illness Metabolic acidosis Kussmaul respiration Osmotic diuresis
Diabetic Keto-Acidosis
Blood glucose levels Urinalysis ABG Urea and creatinine CXR
Investigations
The American Diabetes Association categorizes DKA in adults into one of three stages of severity:
Mild: blood pH mildly decreased to between 7.25 and 7.30 (normal 7.35–7.45); serum bicarbonate decreased to 15–18 mmol/l (normal above 20); the person is alert
Moderate: pH 7.00–7.25, bicarbonate 10–15, mild drowsiness may be present
Severe: pH below 7.00, bicarbonate below 10, stupor or coma may occur
CRITERIA
Fluid replacement Insulin Potassium Bicarbonate
management
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