Ketone, lactic acid & dehydrognase Flashcards
What are Ketone Bodies?
Ketones are synthesized by the liver from fatty acids when a lack of glucose causes the body to use fat for energy.
In low insulin states such as diabetes, fat and fatty acids are metabolized less efficiently than normal, resulting in a buildup of ketones.
Ketone bodies consist of acetone, acetoacetic acid, and beta-hydroxybutyric acid
What are the Ketone bodies used for? Normal ranges?
Ketone bodies only measures acetone and acetoacetic acid, so may need a beta-hydroxybutyrate blood test to differentiate coma due to a hyperosmotic state (negative test expected) from coma due to ketoacidosis .
Normal: negative or 0.30-2.0 mg/dL
Critical level: > 20 mg/dL
Beta-hydroxybutyric acid is the main ketone body in DKA. Extremely elevated levels can lead to coma
What are the symptoms of elevated Ketone Bodies?
Symptoms with elevated level include fruity breath, acidosis, ketonuria, depressed level of consciousness
Where will Ketones appear first?
Ketones appear in the urine before there is a significant increase in the amount in the blood
What does an elevated acetone with a normal anion gap, bicarbonate, and glucose suggest?
Rubbing alcohol (isopropanol) ingestion
When will Ketones be positive?
Ketones will be positive after anesthesia, alcoholism, carbohydrate deficiency, diabetes mellitus, eclampsia, fasting, glycogen storage disease, high fat (ketogenic) diet, hyperglycemia, isopropyl alcohol ingestion, ketoacidosis, pregnant diabetic women, prolonged exercise, reducing diets, starvation, and von Gierke’s disease
What is Lactic Acid used for? Normal values?
Lactate is helpful to document and quantify the degree of tissue hypoxemia due to shock or localized vascular occlusion. Also helpful as a measurement of success in treating these conditions.
Lactate is a sensitive and reliable indicator of tissue hypoxia, which can be caused by local tissue hypoxia (mesenteric ischemia, extremity ischemia) or generalized tissue hypoxia due to shock
Normal: Venous blood: 5-20 mg/dL or 0.6-2.2 mmol/L
Arterial blood: 3-7 mg/dL or 0.3-0.8 mmol/L
What are the types of Lactic Acid?
Lactic acid levels document the presence of tissue hypoxia, determine the degree of hypoxia, and monitor the effect of therapy.
Type I LA is caused by diseases that increase lactate but not related to hypoxia. Examples include glycogen storage diseases, liver diseases, or drugs
Type II LA is caused by hypoxia due to shock, convulsions, and extremity ischemia
Type III LA is idiopathic and is seen in nonketotic patients with diabetes
What are the interfering factors of Lactic Acid?
Prolonged tourniquet use or clenching of the hands can increase lactate levels.
Vigorous exercise can increase levels.
Drugs that increase levels include aspirin, cyanide, ethanol
What can cause Increased Levels of Lactic Acid?
Shock, tissue ischemia – anaerobic metabolism occurs in hypoxemic organs and tissues, and lactic acid is formed.
Carbon monoxide poisoning – CO binds Hgb more tightly than oxygen so no oxygen is available to the tissues, leading to anaerobic metabolism.
Severe liver disease, genetic errors of metabolism – inefficient aerobic glucose metabolism causes increased levels of lactic acid.
Diabetes mellitus (nonketotic) – levels rise in poorly controlled diabetes due to inefficient aerobic glucose metabolism
What is Lactic Dehydrogenase (LDH) used for? Normal Values?
LDH is an intracellular enzyme used to support the diagnosis of injury or disease of the heart, liver, RBCs, kidneys, skeletal muscle, brain, and lungs
Normal: Total LDH 100-190 units/L Isoenzymes: LDH-1 17-27% LDH-2 27-37% LDH-3 18-25% LDH-4 3-8% LDH-5 0-5%
What is Lactic Dehydrogenase (LDH) in the body?
LDH is found in the cells of many body tissues.
LDH is widely distributed through the body, so the total LDH is not a specific indicator of any one disease or injury to any one organ.
Disease or injury cause cells to lyse and release LDH into the bloodstream
What are the Lactic Dehydrogenase (LDH) isoenzymes?
LDH-1 comes mainly from the heart .
LDH-2 comes mainly from the reticuloendothelial system.
LDH-3 comes from the lungs and other tissues.
LDH-4 comes from the kidney, placenta, and pancreas.
LDH-5 comes from the liver and striated muscle.
What does the elevation of each isoenzyme mean?
Isolated elevation of LDH-1 above LDH-2 indicates myocardial injury.
Isolated elevation of LDH-5 indicates hepatocellular disease or injury.
Elevation of LDH-2 and LDH-3 indicates pulmonary injury or disease.
Elevations of all LDH isoenzymes indicate multiorgan injury, advanced malignancy, or diffuse autoimmune inflammatory diseases
How does Lactic Dehydrogenase related to an MI?
With myocardial injury, LDH rises within 24-48 hours after MI, peaks in 2-3 days, and returns to normal in approximately 5-10 days.
LDH is useful for delayed diagnosis of MI in someone who had severe chest pain days earlier with LDH-1 being most sensitive.
When the LDH-1/LDH-2 ratio, which is normally < 1, flips to be > 1, then myocardial injury should be suspected. This usually appears 12-24 hours after MI and is present within 48 hours in about 80% of patients.
With angina only, LDH probably won’t be elevated
