Introduction to laboratory medicine

1. Introduction to laboratory medicine

2. Lipid chemistry and cardiovascular profile • Main lipids in the blood are the triglycerides and cholesterol. • These are insoluble in the water. • Transport in the blood is via lipoproteins. • 4 major classes of lipoproteins. • Chylomicrons • Very low density lipoproteins (VLDL) • Low density lipoproteins (LDL) • High density lipoproteins (HDL)

3. Lipoproteins compositions

4. Composition of lipoproteins

5. lipoproteins • Chylomicrons carry triglycerides (fat) from the intestines to the liver, to skeletal muscle, and to adipose tissue. • Very-low-density lipoproteins (VLDL) carry (newly synthesised) triglycerides from the liver to adipose tissue. • Intermediate-density lipoproteins (IDL) are intermediate between VLDL and LDL. They are not usually detectable in the blood. • Low-density lipoproteins (LDL) carry cholesterol from the liver to cells of the body. LDLs are sometimes referred to as the "bad cholesterol" lipoprotein. • High-density lipoproteins (HDL) collect cholesterol from the body's tissues, and take it back to the liver. HDLs are sometimes referred to as the "good cholesterol" lipoprotein.

6. Chylomicron structure

7. Lipoprotein metabolism

8. CARDIAC PROFILE TEST • ENZYMES • CreatinineKinase –MB(CK-MB) • Lactate Dehydrogenase(LDH 1 and 2) • AspartateAminotransferase(AST)/Serum Glutamate OxaloacetateTransaminase(SGOT) • AlanineAminotransferase(ALT)/ Serum PyruvateTransaminase(SGPT) • LIPID PROFILE • CHOLESTEROL • TRIGLYCERIDE • HDL • LDL

9. Cardiac profile Cardiac Enzymes Cardiac Profile assesses the function of the heart’s muscle and the increased level of enzymes following a myocardial infarction. The cardiac enzymes include the following: • Aspartateaminotransferase (AST) • Lactate dehydrogenase (LD) • CreatineKinase (CK)

10. ASPARTATE AMINOTRANSFERASE (AST) (SGOT) found in all tissue, especially the heart, liver, and skeletal muscles it catalyzes the transfer of the amino group of aspartic acid to alpha-ketoglutaric acid to form oxaloacetic acid and glutamic acid Reaction catalyzed: Amino group Alpha-keto group Oxaloacetate & In aspartic acid in alpha-ketoglutaric acid Glutamate  Reference range: < 35 U/L in male and < 31 in female Considerations in AST assays -Serum is the best specimen -Hemolyzed samples must be avoided -Muscle trauma like intramuscular injections, exercise, or surgical operation can significantly increase AST levels

11. Clinical significance • Myocardial infarction • In myocardial infarction, AST levels are usually 4-10 times the upper limit of normal • These develop within 4-6 hours after the onset of pain • Peak on the 24th – 36th hour • Usually normalize on the 4th or 5th day • Muscular dystrophy • Hepatocellular disorders • Skeletal muscle disorders • Acute pancreatitis

12. Increased levels of AST • Chronic alcohol abuse • Drug hepatoxicity • Pulmonary infarction • Pericarditis • Acute hepatitis • Skeletal muscle disorders

13. Decreased levels of AST • Pregnant women Falsely elevated results • Bilirubin • Aceto-acetatae • N-acetyl compounds • P-aminophenol • Sulfathiozole • Isoniazid • Methyldopa • L-dopa • Ascorbic acid Interferences • Mercury • Cyanide • fluoride

14. LACTATE DEHYDROGENASE (LDH) • Catalyzes the reversible oxidation of lactate to pyruvate • Used to indicate AMI • Is a cytoplasmic enzyme found in most cells of the body, including the heart • Not specific for the diagnosis of cardiac disease

15. Distribution of LD isoenzymes • LD1 and LD2 (HHHH, HHHM) • Fast moving fractions and are heat-stable • Found mostly in the myocardium and erythrocytes • Also found in the renal cortex • LD3 (HHMM) • Found in a number of tissues, predominantly in the white blood cells and brain • LD4 and LD5 (HMMM, MMMM) • Slow moving and are heat labile • Found mostly in the liver and skeletal muscle

16. Considerations in LD assays • Red cells contain 150 times more LDH than serum, therefore hemolysis must be avoided • LDH has its poorest stability at 0°C Clinical Significance • In myocardial infarction, LD increases 3-12 hours after the onset of pain • Peaks at 48-60 hours and remain elevated for 10-14 days • In MI, LD1 is higher than LD2, thus called “flipped” LD pattern

17. flipped LDH An inversion of the ratio of LD isoenzymes LD1 and LD2; LD1 is a tetramer of 4 H–heart subunits, and is the predominant cardiac LD isoenzyme; Normally the LD1 peak is less than that of the LD2, a ratio that is inverted–flipped in 80% of MIs within the first 48 hrs DiffDx.  LD flips also occur in renal infarcts, hemolysis, hypothyroidism, and gastric CA

18. Increased levels of LD • Trauma • Megaloblastic anemia • Pulmonary infarction • Granulocyte leukemia • Hodgekin’s disease • Hemolytic anemia • Infectious mononucleosis • Progressive muscular dystrophy (PMD)

19. CREATINE KINASE (CK) • Is a cytosolic enzyme involved in the transfer of energy in muscle metabolism • Catalyzes the reversible phosphorylation of creatine by ATP • -Is a dimer comprised of two subunits, resulting in three CK isoenzymes • The B, or brain form • The M, or muscle form

20. Three isoenzymes isolated after electrophoresis: • CK-BB (CK1) isoenzyme • Is of brain origin and only found in the blood if the blood-brain barrier has been breached • CK-MM (CK3) isoenzyme • Accounts for most of the CK activity in skeletal muscle • CK-MB (CK2) isoenzyme • Has the most specificity for cardiac muscle • It accounts for only 3-20% of total CK activity in the heart • Is a valuable tool for the diagnosis of AMI because of its relatively high specificity for cardiac injury • Established as the benchmark and gold standard for other cardiac markers

21. Considerations in CK assays • CK is light sensitive and anticoagulants like oxalates and fluorides inhibit its action • CK in serum is very unstable and rapidly loss during storage • Exercise and intramuscular injections causes CK elevations

22. Clinical Significance • -In myocardial infarction, CK will rise 4-6 hours after the onset of pain • -Peaks at 18-30 hours and returns to normal on the third day • -CK is the most specific indicator for myocardial infarction (MI)

23. Raised levels of CK • Progressive muscular dystrophy • Polymyositis • Acute psychosis • Alcoholic myopathy • Hypothyroidism • Malignant hyperthermia • Acute cerebrovascular disease • Trichinosis and dermatomyositis Normal Value: • a. Male – 25-90 IU/mL • b. Female – 10-70 IU/mL

24. CHOLESTEROL • Normal values: range varies according to age • Total Cholesterol: 150-250mg% • Cholesterol esters: 60-75% of the total cholesterol

25. Cholesterol is advised if you • have been diagnosed with coronary heart disease, stroke or mini-stroke (TIA) or peripheral arterial disease (PAD) • are over 40 • have a family history of early cardiovascular disease • have a close family member with cholesterol-related condition • are overweight • have high blood pressure, diabetes or a health condition that can increase cholesterol levels, such as an underactive thyroid

26. Factors leading to raised cholesterol • an unhealthy diet: some foods already contain cholesterol (known as dietary cholesterol) but it is the amount of saturated fat in your diet which is more important • smoking: a chemical found in cigarettes called acrolein stops HDL from transporting cholesterol to the liver, leading to narrowing of the arteries (atherosclerosis) • having diabetes or high blood pressure(hypertension) • having a family history of stroke or heart disease • There is also an inherited condition known as familial hypercholesterolaemia (FH). This can cause high cholesterol even in someone who eats healthy diet.

27. Triglycerides • Ester  derived from glycerol and three fatty acids. • Main lipids in the blood and important energy substrate. • Insoluble in water. • Hypertriglyceridemia • Not an important risk facotr for coronary artery disease. • It can cause pancreatitis when severe. Both hypertriglyceridemia and hypercholesterolemia are associated with various types of cutaneous fat deposition and xanthomatas. Hypertension • Very common clinical problem. Usually essential type meaning that have no identifiable cause. • Investigations for treatable causes like endocrine is necessary.

28. Liver Anatomy of liver

30. Liver histology

32. Functions of liver • Metabolic • Synthesis • Breakdown • Other functions – storage of vitamin A,D,B12,F… • Excretion of waste products from bloodstream into bile • Vascular– storage of blood

33. Synthesis • Protein metabolism • Synthesis of amino acids • Carbohydrate metabolism • Gluconeogenesis • Glycogenolysis • Glycogenesis • Lipid metabolism • Cholesterol synthesis • Lipogenesis • Production of coagulation factors I, II, V, VII, IX, X and XI, and protein C, protein S and antithrombin • Main site of red blood cell production • Produces insulin-like growth factor 1 (IGF-1), a polypeptideprotein – anabolic effects • Production of trombopoetin

34. Breakdown • Breaks down insulin and other hormones • Breaks down hemoglobin • Breaks down or modifies toxic substances (methylation) → sometimes results in toxication • Converts ammonia to urea

35. Other functions • Produces albumin, the major osmolar component of blood serum • Synthesizes angiotensinogen, the hormone responsible for raising blood pressure when activated by renin (enzyme released when the kidney senses low blood pressure)

36. Liver profile The typical Liver Profile test includes • ALT • AST • Alkaline Phosphatase • GGTP • Bilirubin • Prothrombin time • Protein • LDL • Albumin • Globulin.

37. pathogenesis Different cells have different enzymes inside them, depending on the function of the cell. Liver cells happen to have lots of AST, ALT, and GGTP inside them. When cells die or are damaged, the enzymes leak out causing the blood level of these enzymes to rise; that is why the levels of these enzymes in the blood are considered good indicators of liver cell damage. ALT is more specific for liver disease than AST because AST is found in more types of cell (e.g. heart, intestine, muscle). The AST, for instance, will rise after a heart attack or bruised kidney. GGTP and AP are said to be more specific for evaluating biliary disease since they are made in bile duct cells. In liver disease caused by excess alcohol ingestion, the AST tends to exceed the ALT, while the reverse is true to for viral hepatitis.

38. Aminotransferases The normal range is 5-40 IU/L  ALKALINE PHOSPHATASE • Sites • Liver • Gallstone • tumor blocking the common bile duct • alcoholic liver disease • drug-induced hepatitis • Bone, placenta, and intestine. • GGT is utilized as a supplementary test

39. GGT (or GGTP) (0-30 IU/L)  Gamma GlutamylTranspeptidase. This enzyme level is elevated in case of liver disorders.   In contrast to the alkaline phosphatase, the GGT tends not to be elevated in diseases of bone, placenta, or intestine

40. Bilirubin • Jaundice • breakdown of a substance in red blood cells called "heme. • less than 1.1 mg/dL • Increased production • Decreased excretion ALBUMIN 3.5- 5.2 g/dL chronic liver disease Kidney diseases (20 mg/ g of creatinine) GIT diseases Edema and ascites.

41. Prothrombin time • good correlation between abnormalities in prothrombin time and the degree of liver dysfunction. • Expressed in seconds and compared to a normal control patient's blood SPECIALIZED TESTS • serum iron, • the percent of iron saturated in blood, • the storage protein ferritin for hemochromatosis. • accumulation of copper in the liver in wilson disease.

42. Renal profilerenal panel • Glucose • BUN • Creatinine • Potassium • Phosphorous • Sodium • Albumin • BUN/Creatinine Ratio • Calcium • Chloride • Carbon Dioxide (CO2), Total

43. Glucose ( • To find out the cause of renal disease. • Diabetic nephropathy. BUN (7 to 20 mg/dl) • Formed in the liver by the metabolism of the proteins. • Kidney function • May be low if there is liver pathology even if kidneys are normal

44. BUN/Creatinine Ratio • BUN-to-creatinine ratio can help your doctor check for problems, such as dehydration, that may cause abnormal BUN and creatinine levels. • High BUN-to-creatinine ratios occur with sudden (acute) kidney failure, which may be caused by shock or severe dehydration. A low BUN-to-creatinine ratio may be associated with a diet low in protein, a severe muscle injury called rhabdomyolysis, pregnancy, cirrhosis or syndrome of inappropriate antidiuretic hormone secretion (SIADH). Normal Results: 10:1 to 20:1

45. Creatinine (0.8 to 1.4 mg/dl) • It is a breakdown product of creatine (muscle proteine). • Formed in liver and kidney. • Excretion is via klidneys so level raises when kidney is diseased. POTASSIUM(3.7 to 5.2 mEq/L) • the amount of potassium in the blood • High blood potassium levels may be caused by damage or injury to the kidneys PHOSPHORUS • Phosphorus is a mineral that makes up 1% of a person's total body weight. • High levels of phosphorus in blood only occur in people with severe kidney disease or severe dysfunction of their calcium regulation. • Along with excess calcium they may calcify in the soft tissues.

46. Sodium(135 to 145 mEq/L) • High levels of sodium can increase the chance of high blood pressure. • If your total body water is low, high sodium levels may be due to fluid loss from excessive sweating, diarrhea, use of diuretics or burns. • If your total body water is normal, high sodium levels may be due diabetes insipidus or too little of the hormone vasopressin. • If your total body water is high, high sodium levels may indicate hyperaldosteronism, Cushing syndrome, or a diet that's too high in salt or sodium bicarbonate • Low total body water and sodium levels may be due to dehydration, vomiting, diarrhea, over diuresis, or ketonuria • An increase in total body water and low sodium levels may indicate congestive heart failure, nephrotic syndrome or other kidney disease, or cirrhosis of the liver

47. Albumin (3.4 to 5.4 g/dl) • The albumin test measures the amount of albumin in serum, the clear liquid portion of blood and determines if the liver is making enough albumin. This test helps in determining if a patient has liver disease or kidney disease, or if not enough protein is being absorbed by the body. Albumin is one of the two major proteins in the blood, the other is Globulin.  Albumin also helps carry some medicines and other substances through the blood and is important for tissue growth and healing.  Because albumin is made by the liver, decreased serum albumin may result from liver disease.  It can also result from kidney disease which allows albumin to escape into the urine.  Decreased albumin may also be explained by malnutrition or a low protein diet

48. CO2 (total) • This test measures the amount of carbon dioxide in the liquid part of your blood. Carbon dioxide (CO2) is a gaseous waste product made from metabolism. The blood carries carbon dioxide to your lungs, where it is exhaled. Changes in your CO2 level suggest you may be losing or retaining fluid, cause an imbalance in your body's electrolytes. Electrolytes are minerals in your blood and other body fluids. • Abnormal levels of carbon dioxide suggest your body is having trouble maintaining its acid-base balance and your electrolyte balance is upset.Normal Results: 20 to 29 mEq/L

49. Calcium (8.5 to 10.2 mg/dl) • To build and fix bones and teeth • help nerves work • make muscles contraction • help blood clot • and help the heart to work. • The Calcium test screens for problems with the parathyroid glands or kidneys, certain types of cancers and bone problems, inflammation of the pancreas (pancreatitis), and kidney stones. CHLORIDE(96 to 106 mEq/L) Chloride levels can be used to help monitor high blood pressure, heart failure and kidney disease.  High levels of chloride, known as hyperchloremia, typically indicate dehydration, metabolic acidosis and other conditions.  Decreased levels of chloride, known as hypochloremia, can indicate kidney disorder, Addison's disease, congestive heart failure and other conditions.

50. Bone metabolism • Bone is constantly remodelling • Bone resorption= bone formation • Why remodelling is necessary? • To withstand changing environment • To cope with workload • To repair damage caused by recurrent microtraumas BONE METABOLISM Osteoclasts and Osteoblasts Osteocytes Encased osteoblasts which are connected to each other by long cellular processes forming a network connected by gap junctions.