Laboratory Tests and Diagnostic Procedures.pptx

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1. Laboratory Tests and Diagnostic Procedures

2. Laboratory Tests an extension of physical examination in which tissue , blood , urine or other specimens are obtained from patients and subjected to microscopic, biochemical, microbiological or immunological examination. help us in identifying the nature of the disease. may be done on the bedside or in a laboratory.

3. Classifications 1. Screening tests - primary purpose is to detect early disease or risk factors for disease in large numbers of apparently healthy individuals. 2. Diagnostic tests - purpose is to establish the presence (or absence) of disease as a basis for treatment decisions in symptomatic or screen positive individuals (confirmatory test).

4. Screening tests Diagnostic tests Purpose To detect potential disease indicators To establish presence/absence of disease Target population Large numbers of asymptomatic, but potentially at risk individuals Symptomatic individuals to establish diagnosis, or asymptomatic individuals with a positive screening test Test method Simple, acceptable to patients and staff Maybe invasive, expensive but justifiable as necessary to establish diagnosis Positive result threshold Generally chosen towards high sensitivity not to miss potential disease Chosen towards high specificity (true negatives). More weight given to accuracy and precision than to patient acceptability Positive result Essentially indicates suspicion of disease (often used in combination with other risk factors) that warrants confirmation Result provides a definite diagnosis Cost Cheap, benefits should justify the costs since large numbers of people will need to be screened to identify a small number of potential cases Higher costs associated with diagnostic test maybe justified to establish diagnosis.

5. Hematology Microbiology Biochemistry Immunology/Serology Histopathology and Cytopathology Common Laboratory Services offered in Hospitals

6. Crucial Q&As prior to Laboratory Investigations: 1. WHAT determines the investigation to be taken? must be based on the facts obtained from history taking and clinical examination Investigations are useful only when the appropriate tests are requested, and interpreted in the light of history, clinical findings, knowledge and experience. Before any investigations are initiated, Patient Consent must be obtained

7. 2. What sample to be collected for the Test? Samples should optimally be the most likely entity which harbours the causative organism or abnormal constituents of body fluids like electrolytes, chemical compounds or antigens.

8. 3. How to collect specimens? Success or failure of the investigation depends on the procedures carried out in collection, preservation and transport of the specimens. In cases of microbiological and culture tests, the specimen must be material from the actual site of infection and should be collected with minimum of contamination from adjacent tissues or secretions. In cases of tissue collection, the site of collection as well as the vicinity with respect to the lesion assumes importance the timing of specimen collection is also important.

9. In general specimens collected from swabs are inferior in material collection when compared to aspirates. In cases of collection of blood samples for haematology, it can be collected either via skin, venous or arterial puncture If a clinician wishes to study its cellular components, its important that the blood sample remain unclotted. If blood specimen has been refrigerated, it must be brought back to room temperature for investigations as cold specimens yield false values.

10. 4. What Information to be furnished to the laboratory? Specimens should accompany properly filled out forms from the clinician Preliminary details include: Name, Address, Hosp. No., Gender & Date of Birth Other important details are: Exact nature of the specimen Source of the specimen Nature of investigation requested Date and time of specimen collection Brief Clinical Details Tentative Diagnosis Current Therapy if any

11. HEMATOLOGY

12. Hematology involves the study of the blood, in particular how blood can affect overall health or disease. include tests on the blood, blood proteins and blood-producing organs. it can evaluate a variety of blood conditions including infection, anemia, inflammation, hemophilia, blood-clotting disorders, leukemia and the body’s response to chemotherapy treatments. may be routine and regular, or they may be called upon to diagnose serious conditions in urgent situations.

13. Hematology Includes: CBC, WBC, Hemoglobin, Coagulation profile, hematocrit, etc. blood samples are usually taken and stored in a Lavender / purple top tube - EDTA and/or blue top

14. one of the most common blood tests. can help detect blood diseases and disorders, such as anemia, infections, clotting problems, blood cancers and immune system disorders. Peripheral venous blood is collected in a lavender tube (contains the anticoagulant EDTA) and should be thoroughly mixed Unacceptable specimen: Clotted or greater than 48 hours old Methodology of testing: Whole blood analyzer Completed Blood Count

15. Red Blood Cells SI unit (normal value): Male 14–18 g/dL Female 12–16 g/dL Deficiency of RBC: Hemolytic anemia: decrease no. of RBC Excess bleeding Hereditary spherocytosis: rare blood disorder in which defects in the red blood cells cause them to be shaped like spheres and break down easily.

16. Elevation of RBC: Polycythemia: Over production of RBC Primary polycythemia: caused by overproduction of red blood cells by the bone marrow due to mutation or biological factor in the body. Secondary polycythemia: which is caused by factors that reduce the amount of oxygen reaching the body's tissues, such as smoking, high altitude or congenital heart disease. The red blood cells in some patients with secondary polycythemia may carry an abnormal form of hemoglobin that does not release oxygen readily (high-affinity hemoglobin).

17. Red blood cell enzyme disorders: Red blood cell enzyme disorders are important to recognize and diagnose for proper supportive care, monitoring, and treatment. Glucose-6-phosphate dehydrogenase (G6PD) deficiency is an X- linked disorder most commonly characterized by episodic haemolysis in the setting of oxidative triggers, such as fava beans, infections, and certain medications.

18. Enzymopathies , such as pyruvate kinase deficiency , should be suspected in patients of all ages with a chronic hemolytic anaemia in the absencevof immune-mediated haemolysis, a hemo-globinopathy, or evidence of a red cell membrane disorder. Splenectomy partially ameliorates the anaemia in most patients with pyruvate kinase deficiency and other red blood cell enzyme disorders.

19. Glycolytic red cell disorders cause congenital hemolytic anemias with wide clinical heterogeneity and frequent complications, including neonatal jaundice, gallstones, and both transfusion-related and transfusion-independent iron loading. Mean Corpuscular Volume (MCV): MCV is a measure of the average size of your RBC. Abnormal MCV levels may be a sign of anemia or thalassemia. Normal value: 76-100 mm3 Macrocytic: increase RBC size Microcytic: decrease RBC size

20. Normocytic: hemoglobin levels are decrease but RBC size is normal (acute blood loss, anemia of chronic disease. Microcytic: insufficiency of hemoglobin synthesis (iron deficiency of anemia, thalassemia) Macrocytic: deficiency of vitamin B1 or folic acid (hypothyroidism, alcoholism) Sickle cell anemia: alteration in hemoglobin structure Hematocrit: Hematocrit is a measure how much space red blood cells take up in your blood. A high hematocrit level might mean dehydrated. A low hematocrit level might mean have anemia. Abnormal hematocrit levels also may be a sign of a blood or bone marrow disorder.

21. Hematocrit Measure of RBC percent of total blood vol Indirect measure of RBC # & volume Part of “routine” testing and anemia evaluation Normal: 36 – 48% Critical: < 15% or > 60%

22. White Blood Cells SI unit (normal value): 5,000 – 10,000 / ml Deficiency of WBC: 1. Leukopenia: decrease no. of WBC 2. Neutropenia: decrease no. of neutrophils (aplastic anemia, chemotherapy, myelodysplasia, typhoid fever, hyperglycemia) Basopenia: decrease no of basophils (thyrotoxicosis, acute hypersensitivity reactions) Lymphocytopenia: decrease no of lymphocytes (viral infection,systemic lupus erythematosus (SLS), rheumatoid arthritis, myasthenia gravis) Monocytopenia: decrease no of monocytes MonoMac Syndrome (the risk of infection with certain organisms, including a group of bacteria known as Mycobacterium avium complex (MAC) that are related to tuberculosis, human papillomavirus (HPV), and certain fungi. Neutrophils: 50 – 70% Lymphocytes: 20 – 40% Monocytes: 2 – 8% Eosinophils: 0 – 5% Basophils: 0 – 2%

23. Elevation in WBC: Leukocytosis: increase no. of WBC Neutrophilic leukocytosis: increase no of neutrophils Basophilia: increase number of basophils (hypothyroidism, myeloproliferative disorders) Eosinophilia: increase number of eosinophils (parasitic and fungal disease, allergies, skin disorders, toxins) Lymphocytic leukocytosis: increase of lymphocytes Monocytosis: increase number of monocytes (sarcoidosis, and Langerhans cell histiocytosis, autoimmune disorder)

24. SI unit (normal value): 150000-450000/μL Deficiency of Platelets: Thrombocytopenia: low number of platelets Elevation in Platelets: Thrombocytosis: increase number of platelets (acute bleeding and blood loss, cancer, infections, removal of spleen, Platelets

25. Factor V assay: This test measures Factor V, a substance involved in clotting. An abnormally low level may be indicative of liver disease, primary fibrinolysis (a breakdown of clots), or disseminated intravascular coagulation (DIC). Fibrinogen level Fibrinogen is a protein made by your liver. This test measures how much fibrinogen is in your blood. Abnormal results may be a sign of excessive bleeding or hemorrhage , fibrinolysis , or placental abruption , which is a separation of the placenta from the uterine wall. Blood clotting test:

26. Prothrombin is another protein your liver produces. The prothrombin time (PT) test measures how well and how long it takes your blood to clot. It normally takes about 25 to 30 seconds. It may take longer if you take blood thinners. Other reasons for abnormal results include hemophilia, liver disease, and malabsorption . It’s also useful in monitoring those who take medications that affect clotting, such as warfarin (Coumadin). Typical reference ranges for healthy adults are: Blood clotting test Time/ concentration PT 9.0-11.7 sec INR (coumadin) 0.9-1.2 sec PTT (Heparin monitoring) 55.0-75.0 sec APTT (therapeutic) 23.3-31.9 sec Fibrinogen 203-377 mg/dl Prothrombin time (PT or PT-INR)

27. Prothrombin Time (PT) - Increased PT: Disseminated Intravascular Coagulation Patients on Warfarin Therapy Vit. K deficiency Early & End stage Liver failure

28. 2. Activated Partial Thromboplastin Time (aPTT): Time in seconds that’s required for a clot to form in citrated or oxalated plasma Performance indicator of both the intrinsic & common pathways Typical reference range – 30-40 secs Increased aPTT seen in : Patients on Heparin Therapy Von – Willebrand’s disease Disseminated Intravascular Coagulation Early Stage Liver failure/ Wilson’s disease Haemophilia

29. BIOCHEMISTRY

30. Biochemistry analyzes the blood plasma (or serum) for a wide variety of substances (substrates, enzymes, hormones, etc.) also includes analysis of other body fluids (eg, urine, ascitic fluids, CSF) Serum - is that portion of blood remaining after whole blood has been allowed to clot - responsible for fluid maintenance Intra and extra cellularly - responsible for the optimal osmotic gradient, nerve and muscle function and hydration

31. Biochemistry includes: Blood Glucose estimations, Oral Glucose Tolerance test, Glycated Haemoglobin (HbA 1c ), and serum electrolytes blood samples are usually taken and stored in a yellow top

32. Blood Glucose Estimations: Fasting Blood Sugar (FBS): Normal values – 70-90 mg/100ml Random Blood Sugar (RBS): 110-130 mg/100ml Post Prandial Blood Sugar (PPBS): <140 mg/100ml High values are seen in Diabetes mellitus, Cushing’s disease, pheochromocytoma, in patients taking corticosteroids Low values seen in insulin secreting tumors, Addison’s, Pituitary hypofunction Biochemistry

33. Oral Glucose Tolerance Test: Used for the definitive diagnosis of diabetes mellitus and for distinguishing diabetes from other causes of hyperglycemia like hyperthyroidism Should be performed on only healthy ambulatory patients who are not under any drugs which may interfere with glucose estimation Oral Glucose Challenge: OGCT (challenge Test) is a short version of OGTT used in pregnant women to check for Gestational Diabetes

34. Oral Glucose Tolerance Test: Fajans & Conn Criteria: Abnormally increased values of any 2 parameters indicate diabetes Fasting Blood Sugar > 100 mg/dl 1 hr. BS > 160 mg/dl 2 hr. BS > 120 mg/dl

35. Oral Glucose Tolerance Test: Wilkerson Point System: A score of 2 or more indicates diabetes FBS > 110 mg/dl – 1 Point 1 hour > 170 mg/dl – 0.5 point 2 hour > 120 mg/dl – 0.5 point 3 hour > 110 mg/dl – 1 point

36. Oral Glucose Tolerance Test: University Group Diabetes Program Criteria: Based on the sum of 1,2 and 3 hr. levels of Blood sugar If sum >/= 500 mg/dl a diagnosis of diabetes is made

37. 3. Glycated Haemoglobin (HbA 1c ): Hb becomes Glycated by ketoamine reactions between glucose and other sugars. Once Hb is Glycated, it remains that way for a prolonged period (2-3 months) Hence it provides a definitive value of blood sugar control of 2-3 month duration The HbA 1c fraction is abnormally elevated in diabetic patients with chronic hyperglycaemia It is considered to be a better indicator for diabetic control compared to blood glucose levels

38. Glycated Haemoglobin (HbA 1c ):

39. Serum Calcium, Phosphorus: Indicated on suspicion of fibrous dysplasia, primary and secondary hyperparathyroidism, osteoporosis, multiple myeloma or osteosarcoma The concentration of Serum Ca varies inversely with serum P Normal level Serum Ca – 9.2-11 mg/dl Normal level Serum P – 3- 4.5 mg/dl At levels less than 7 mg/dl Serum Ca, signs of tetany may appear

40. Serum Alkaline Phosphatase: (ALP) ALP produced in small amounts in the liver but most notably in osteoblasts Normal values: ADULT CHILD King Armstrong Units 4-13 15-30 Bodansky Units 1.5-4.5 5-14 International Units
(IU/l) 30-85

41. Serum Alkaline Phosphatase: (ALP) This test is very useful for diagnosing biliary obstruction. Even in mild cases of obstructive disease, this enzyme is elevated. It is not very useful for diagnosing cirrhosis. If a patient has bone disease, this test may be highly inaccurate, as ALP is also found in bone tissue.

42. High values Low values Obstructive liver disease Hypophosphatasia Paget’s disease of bone Hypothyroidism Osteomalacia Osteoporosis Rickets Aplastic/Pernicious anaemia Sarcoidosis Chronic Myeloid Leukaemia Lymphoma Wilson’s Disease

43. 6. Serum Uric Acid: End product of purine metabolism Normal values: Males : 2.1-7.8 mg/dl Females : 2.0-6.4 mg/dl Abnormally high uric acid level seen in Gout, Renal failure, leukaemia, lymphoma, starvation, lead poisoning & cancer chemotherapy Low values are rare (ex. Wilson's disease - which is an inherited disorder that causes copper to build up in your body tissues)

44. 7. Serum Creatinine: Metabolic product of dephosphorylation of creatinine phosphate Raised in late stage Renal disease Its analysis is preferred to Serum Urea analysis as dietary protein intake and protein catabolism do not alter its levels in the body Levels > 15 mg/dL indicates impaired renal metabolism

45. 8. Blood Urea Nitrogen: Formed by the deamination of amino acids in the liver Protein metabolism produces ammonia, a toxic substance that is converted into urea. Normal values – 8 -18 mg/100ml High BUN readings are seen in acute or chronic renal failure, congestive heart failure and urinary tract obstructions

46. 9. Total Protein & Albumin / Globulin Ratio: These proteins are important in coagulation, transport a variety of hormones, act as buffer systems and help maintain osmotic pressure Normal range: Total protein – 6 – 8.3 g/dL A/G ratio – 1.2 – 2.0

47. Total Protein & Albumin / Globulin Ratio: High Total Protein Values Low Total Protein Values Lupus erythematosus Inadequate Protein Intake Collagen diseases Protein Malabsorption Acute liver diseases Diarrhoea Multiple Myeloma Anaemia & Burns

48. 10. Serum Bilirubin: Bilirubin is a bile pigment derived from the breakdown of Hemoglobin Normal value: 0.1 – 1.2 mg/100ml Levels beyond 3.0 mg/100ml may indicate jaundice High values may also indicate hemolytic anaemia, biliary obstruction, hepatitis and Gilbert’s disease 66

49. 11. LDH, SGOT, SGPT: LDH is responsible for the oxidation of lactic acid to pyruvic acid Normal range: 71-207 IU/L SGOT (AST) is responsible for conversion of amino acids to keto acids Normal range: 0-35 IU/L SGPT (ALT) is responsible for diagnosis of liver functions more so than SGOT levels Normal range: 0-35 IU/L

50. LDH, SGOT, SGPT: These enzymes can be indicative of liver disease. However, these enzymes are also found in other body tissues such as bone, heart, kidney, etc. Isoenzyme tests usually must be performed in order to isolate the isoenzyme that is elevated and if the source is the liver.

51. 12. Blood Electrolytes: An automated analysis usually includes Sodium (Na), Potassium (K), chloride (Cl) and Bicarbonates (HCO 3 ) Normal values: - Sodium 136-145 mEq/L Potassium 3.8-5.5 mEq/L Chloride 95-105 mEq/L Bicarbonates 22-28 mEq/L

52. MICROBIOLOGY

53. Microbiology body fluids, mucosal surfaces and excised tissues are examined by using microscopical, cultural and serological techniques. To detect and identify the causative microorganism

54. Microbiology These includes: Blood culture & sensitivity CSF- culture & sensitivity Pus culture & sensitivity Antibiotic sensitivity testing Sputum culture & sensitivity

55. Blood Culture & Sensitivity used to detect bacteria or fungi in a person's blood. blood sample is drawn

56. CSF - Culture & Sensitivity used to detect infectious organisms in the CSF “gold standard” for diagnosis of meningitis

57. Pus Culture & Sensitivity A sterile swab may be used to collect cells or pus from a superficial wound site. From deeper wounds, aspirations of fluid into a syringe

58. Antibiotic Sensitivity Testing determine the right antibiotic treatment for an infection and to monitor changes in bacterial resistance to antibiotics blood sample is drawn

59. IMMUNOLOGY / SEROLOGY

60. Immunology / Serology Detects abnormalities of the immune system Primary role to Identify a disease is by observing the presence of an antibody in the patient that resulted from the infection (entry of pathogen)

61. HISTOPATHOLOGY and CYTOPATHOLOGY

62. Histopathology Deals with the identification of structural changes in diseased tissues through microscopic examination of appropriately stained tissue sections obtained from biopsy procedures.

63. Cytopathology involves the study of cells or cell types in disease. samples of abnormal cells are collected from lesional tissue scrapings or by means of tissue aspiration. cells are then stained and studied under light microscopy

64. Histopathology and Cytopathology:

65. Histopathology and Cytopathology: Histopathology refers to the microscopic examination of tissue in order to study the manifestations of the disease Cytopathology refers to the scientific study of role of individual cells or cell types in disease

66. Additional Tests Urinalysis - set of screening tests that can detect some common diseases. - involves checking the appearance, concentration and content of urine. - may be used to screen for and/or help diagnose conditions - 30-60 ml specimen sample needed

67. Urinalysis Normal Values Appearance: clear Color: amber yellow Odor: aromatic pH: 4.6 – 8 Protein: 0 – 8 mg/dL Specific gravity: 1.005 – 1.030 Leukocyte esterase: negative Nitrites: none Ketones: none

68. Additional Tests Stool analysis - examined for hidden (occult) blood, fat, meat fibers, bile, white blood cells, and sugars called reducing substances. - detects the bacteria causing an infection. - ideally 2 to 5 grams specimen sample

69. DIAGNOSTIC PROCEDURES

70. Diagnostic Procedures an examination to identify an individual's specific areas of weakness and strength in order determine a condition, disease or illness. Classified into: Non – invasive Invasive

71. Non - invasive diagnostic procedure do not involve tools that break the skin or physically enter the body. include x-rays, CT scan, MRI, ECG, and Holter monitoring.

72. X-ray a quick, painless test that produces images of the structures inside your body — particularly your bones. X-ray beams pass through your body, and they are absorbed in different amounts depending on the density of the material they pass through. Dense materials, such as bone and metal, show up as white on X-rays. The air in your lungs shows up as black. Fat and muscle appear as shades of gray.

73. X-ray For some types of X-ray tests, a contrast medium — such as iodine or barium — is introduced into your body to provide greater detail on the images.

74. Computed Tomography (CT) scan allows doctors to see inside your body. It uses a combination of X-rays and a computer to create pictures of your organs, bones, and other tissues. Unlike a conventional x-ray—which uses a fixed x-ray tube—a CT scanner uses a motorized x-ray source that rotates around the circular opening of a donut-shaped structure called a gantry.

75. Computed Tomography (CT) scan

76. Magnetic Resonance Imaging (MRI) produces three dimensional detailed anatomical images. It is often used for disease detection, diagnosis, and treatment monitoring. It is based on sophisticated technology that excites and detects the change in the direction of the rotational axis of protons found in the water that makes up living tissues.

77. Magnetic Resonance Imaging (MRI)

78. Electrocardiogram (ECG) One of the simplest and fastest tests used to evaluate the heart. Electrodes (small, plastic patches that stick to the skin) are placed at certain spots on the chest, arms, and legs. The electrodes are connected to an ECG machine by lead wires. The electrical activity of the heart is then measured, interpreted, and printed out. No electricity is sent into the body.

79. Electrocardiogram (ECG) Natural electrical impulses coordinate contractions of the different parts of the heart to keep blood flowing the way it should. An ECG records these impulses to show how fast the heart is beating, the rhythm of the heart beats (steady or irregular), and the strength and timing of the electrical impulses as they move through the different parts of the heart. Changes in an ECG can be a sign of many heart-related conditions.

80. ECG Leads Placement

81. Holter Monitoring uses a holter machine to detect irregularities of the heart rhythm not detected by ECG varies from 24 to 48 hours, depending on what condition

82. Mammogram an X-ray examination of the breast. used to detect and diagnose breast disease in women who either have breast problems, such as a lump, pain, or nipple discharge, as well as for women who have no breast complaints. allows detection of breast cancers , benign tumors, and cysts before they can be detected by palpation (touch). it cannot prove that an abnormal area is cancer, but it raises a significant suspicion of cancer

83. Invasive Diagnostic Procedures requires trained medical providers to use instruments that cut skin (or other connective tissue) or that are inserted into a body opening. Examples of invasive tests include biopsy, colonoscopy and endoscopy.

84. Biopsy involves extraction of sample cells or tissues for examination to determine the presence or extent of a disease. typically used to diagnose Cancer have different types

85. Bone Marrow Biopsy commonly used to diagnose a variety of blood problems — both noncancerous and cancerous — including blood cancers, such as leukemia, lymphoma and multiple myeloma. may also detect cancers that started elsewhere and traveled to the bone marrow.

86. Endoscopic biopsy During endoscopy, your doctor uses a thin, flexible tube (endoscope) with a light on the end to see structures inside your body. Special tools are passed through the tube to take a small sample of tissue to be analyzed.

87. Needle Biopsy During a needle biopsy, your doctor uses a special needle to extract cells from a suspicious area. A needle biopsy is often used on tumors that your doctor can feel through your skin, such as suspicious breast lumps and enlarged lymph nodes.

88. Skin Biopsy removes cells from the surface of your body. used most often to diagnose skin conditions, including melanoma and other cancers.

89. Colonoscopy the endoscopic examination of the large bowel and the distal part of the small bowel with a CCD camera or a fiber optic camera on a flexible tube passed through the anus.

90. Endoscopy a procedure which uses an endoscope to examine the interior of a hollow organ or cavity of the body. Unlike many other medical imaging techniques, endoscopes are inserted directly into the organ.

91. END. ✤