محاضرات كلية بلاد الرافدين التشخيص المخبري 8.pptx

التشخيص المخبري

1. Diagnostic skills of laboratory tests for common disease cases and reading their results: Types of laboratory samples Types of tests and methods of collecting samples The results of laboratory tests. By: Dr. Mohammed Mohammed Abdullah Yassin Bachelor in medical laboratory science (MLS) Jiblah University for medical and health science

2. INTRODUCTION Lab tests, along with a health history and physical exam, are used by physicians to diagnose and manage health conditions. When the body is healthy, it functions normally in a state of homeostasis or equilibrium. When the body is in homeostasis, the values for fluids, chemicals, electrolytes, and secretions ( hormones ) are typically within an acceptable or “normal” range.

3. INTRODUCTION When the body has a pathologic condition (e.g. a disease state), these ranges can change as a result of an imbalance in your body. The disease can cause the imbalance, and vice versa, the imbalance may cause the disease. Lab tests can help identify these imbalances which will aid the medical professional in understanding and treating the underlying problem. 

4. Reasons for Ordering a Laboratory Test A diagnostic test could be used in clinical settings for confirmation/exclusion, triage, monitoring, prognosis, or screening: Diagnosis: Confirmation/exclusion (to rule in or rule out a diagnosis). Monitoring: A repeated test that allows assessing the efficacy of an intervention ( eg , the effect of drug therapy). Screening: Presence of the disease in apparently asymptomatic persons ( eg , for congenital hypothyroidism via neonatal thyroxine testing). Prognosis: Assessment of an outcome or the disease progression. Research (to unde rstand the pathophysiology of a particular disease process).

5. Questions to Ask Before Ordering a Laboratory Test An understanding of which laboratory tests are appropriate to order in the diagnosis and follow up of a patient’s medical condition should include prior consideration of the answers to the following questions: Why is the test being ordered? What are the consequences of not ordering the test? How good is the test in discriminating between health versus disease? How are the test results interpreted? How will the test results influence patient management and outcome? The answers to these questions are critical to the optimal selection and cost-effective use of laboratory tests likely to benefit patient management.

6. Laboratory Testing Cycle The “laboratory testing cycle” ( Figure 1 ) consists of all steps between the time when a clinician thinks about and orders a laboratory test and the time the appropriate patient’s sample for testing is obtained ( eg , a blood specimen taken from an antecubital vein) and the results of the testing are returned to the clinician (often called the “vein-to-brain” turnaround time [TAT] of test results). This cycle consists of 3 phases:  preanalytical phase, Analytical phase, Post-analytical phase: Figure 1: The “Laboratory Testing Cycle.”

7. Types of Laboratory samples Laboratory samples, also known as specimens, are biological materials collected from patients for laboratory analysis. These samples help diagnose, monitor, and treat various health conditions. Laboratory samples are critical for diagnosing diseases, conducting research, and monitoring health conditions. Each type of sample serves a specific purpose and provides unique insights into the patient’s health. The kinds of specimen that are commonly collected from humans, including blood, stool, urine, sputum, skin snips, and other tissue biopsies, and swabs or smears collected from skin or mucosal surfaces.

8. 1. Blood Samples the blood plays a big role in overall health and contains a lot of information about what may be going on in the body. That’s one reason why blood tests are a common medical test. Blood tests are used to measure or look at cells, chemicals, proteins, or other substances in your  blood . Blood testing, also known as blood work, is one of the most common types of lab tests. Blood work is often included as part of a  regular checkup .

9. 1. Blood Samples Blood sample are also used to: Help diagnose certain diseases and conditions. Monitor a chronic (long-lasting) disease or condition, such as  diabetes  or high  cholesterol . Find out if treatment for a disease is working. Check how well your organs are working. Your organs include your liver, kidneys, heart, and thyroid. Help diagnose  bleeding  or clotting disorders. Find out if your  immune system  is having trouble fighting infections.

10. 1. Blood Samples Types: Whole Blood : Composition : Red blood cells (RBCs), white blood cells (WBCs), platelets, plasma (liquid portion). Uses : Complete Blood Count (CBC): Evaluates overall health and detects disorders like anemia, infection, and leukemia. Blood Typing and Crossmatching: Determines blood group and compatibility for transfusions. Blood Cultures: Identifies bacterial or fungal infections in the blood

11. 1. Blood Samples Types: Serum: Composition: Plasma without clotting factors (obtained after blood coagulation and centrifugation). Specific Uses: Biochemical Tests: Measures levels of proteins, hormones, and electrolytes (e.g., liver enzymes, kidney function tests). Serology: Detects antibodies and antigens for infectious diseases (e.g., HIV, hepatitis).

12. 1. Blood Samples Types: Plasma: Composition: The liquid part of blood including clotting factors (obtained from anticoagulated blood). Specific Uses: Coagulation Studies: Assesses blood clotting ability (e.g., PT/INR, aPTT ). Plasma Protein Levels: Measures proteins like albumin and globulins.

13. 1. Blood Samples Types: Buffy Coat : Composition : WBCs and platelets layered between RBCs and plasma after centrifugation. Uses : Genetic studies, molecular diagnostics. Specific Uses: Diagnosis : Identifies conditions like anemia, infections, and leukemia. Monitoring : Tracks chronic disease management and treatment efficacy. Screening : Detects conditions like diabetes and cardiovascular diseases.

14. 2. Urine Samples Urine is actually a “fluid biopsy” of the kidneys and can provide a fountain of information about the health of an individual. The kidneys are the only organs that can have their functional status evaluated by such a noninvasive means. In addition, because urine is an ultrafiltrate of the plasma, it can be used to evaluate and monitor body homeostasis and many metabolic disease processes. The purposes of performing a routine urinalysis are (1) to aid in the diagnosis of disease; (2) to screen for asymptomatic, congenital, or hereditary disease; (3) to monitor disease progression; and (4) to monitor therapy effectiveness or complications.

15. 2. Urine Samples Composition: Urine is a liquid waste product composed of Primarily water, with dissolved electrolytes, urea, creatinine, uric acid, and other waste products. Can contain cells, bacteria, proteins, glucose, ketones, or other substances depending on the health status. the volume and solute composition of urine can vary greatly depending on an individual’s diet, physical activity, and health. Because of these variables, normal (i.e., reference) urine values for each organic and inorganic component are difficult to establish. Urine is an ultrafiltrate of plasma with selected solutes reabsorbed, other solutes secreted, and the final water volume determined by the body’s state of hydration. Excreted urine is normally 94% water and 6% solutes, (Urea , Chloride , Sodium, Potassium , NH4 , Inorganic PO4 , Inorganic SO4 , Creatinine , Uric acid , Glucose , Albumin)

16. 2. Urine Samples Types of Urine Samples: Random Urine : Composition : A mix of urine produced throughout the day. Uses : Routine screenings, dipstick tests for glucose, protein, and pH.

17. 2. Urine Samples Types of Urine Samples: First Morning Urine : Composition : Concentrated due to overnight collection. Uses : Pregnancy tests Detection of hCG hormone , hormone evaluations. 24-Hour Urine : Composition : Urine collected over a 24-hour period. Uses : Kidney Function Tests: Measures creatinine clearance and protein excretion. Metabolic Disorders: Assesses excretion rates of substances like calcium or uric acid.

18. 2. Urine Samples Types of Urine Samples: Timed Urine: Quantitative analysis of substances like creatinine, hormones, or electrolytes. Clean-Catch Midstream: Urine culture to diagnose urinary tract infections (UTIs).

19. 2. Urine Samples Specific Uses : Diagnosis : Detects UTIs, urine culture, kidney disorders, Diabetes, liver disease. and metabolic abnormalities. Monitoring : Evaluates the effectiveness of treatments and kidney function. Screening : Drug testing and certain diseases. Biochemical Analysis: Measures glucose, protein, or ketones for diabetes monitoring. Microscopic Examination: Identifies cells, casts, crystals, and microorganisms in the urine.

20. 3. Stool Samples Composition : Normally, about 100 to 200 g of fecal material is passed each day. The feces consist of undigested foodstuffs (e.g., cellulose), sloughed intestinal epithelium, intestinal bacteria, gastrointestinal secretions (e.g., digestive enzymes), bile pigments, electrolytes, and water. Because of the slow movement of fecal material in the large intestine, it normally takes 18 to 24 hours for the contents presented to it by the small intestine to be excreted as feces.

21. 3. Stool Samples Examination of feces provides important information that aids in the differential diagnosis of various gastrointestinal tract disorders, which range from maldigestion and malabsorption to bleeding or infestation by bacteria, viruses, or parasites. Hepatic and biliary conditions that result in decreased bile secretion, as well as pancreatic diseases that cause insufficient digestive enzymes, also are identifiable by fecal analysis. By far the test that currently is most commonly performed on feces is the chemical test for occult, or hidden, blood. Occult blood is recognized as the earliest and most frequent initial symptom of colorectal cancer. Fecal blood testing is recommended to be performed routinely on all individuals 50 years of age and older. Fecal analysis is also valuable for determining the presence of increased fecal lipids (steatorrhea) and in the differential diagnosis of diarrhea.

22. 3. Stool Samples Specific Uses : Detection of gastrointestinal infections (e.g., bacteria, parasites, viruses). Fecal occult blood test (FOBT) Detects hidden blood in the stool, which can be a sign of colorectal cancer, and to screen for gastrointestinal bleeding. Fecal fat analysis (to diagnose malabsorption conditions). Evaluation of digestive health (e.g., inflammation markers). Screening For inflammatory bowel diseases (e.g., Crohn’s disease, ulcerative colitis). Monitoring: Assesses treatment effects and disease activity .

23. 6. Cerebrospinal Fluid (CSF) Samples Composition : Clear fluid around the brain and spinal cord, containing glucose, proteins, and cells. Specific Uses : Diagnosis : Identifies CNS infections like meningitis and encephalitis. Assessment : Evaluates neurological diseases such as multiple sclerosis. Monitoring : Tracks disease progression and treatment effects. Cell Count, Protein, Glucose: Helps in diagnosing conditions such as bacterial or viral infections and assessing the blood-brain barrier function.

24. 6. Cerebrospinal Fluid (CSF) Samples Specific Uses :

25. 4. Sputum Samples Composition : Sputum is a mixture of mucus, cellular debris, bacteria, and white blood cells produced by the lungs , fungi, and other pathogens from the respiratory tract. Specific Uses : Diagnosis : Identifies respiratory infections like tuberculosis and pneumonia. Screening : Detects cancer cells in the lungs. Evaluation: Assesses chronic conditions such as chronic obstructive pulmonary disease (COPD).

26. 5. Tissue Samples (Biopsies) Types: Fine Needle Aspiration (FNA) : Composition : Cells from a mass or lesion. Uses : Initial diagnostic for tumors or cysts. Core Biopsy : Composition : Cylindrical tissue sample from a lesion. Uses : Detailed analysis of tumors, especially for cancer diagnosis. Excisional Biopsy : Composition : Entire lump or area of concern. Uses : Comprehensive evaluation for malignancies and large lesions.

27. 5. Tissue Samples (Biopsies) Specific Uses : Diagnosis : Identifies cancers, infections, and autoimmune diseases. Assessment : Determines the extent and stage of diseases. Monitoring : Tracks disease progression and treatment response.

28. 7. Saliva Samples Composition : Water, enzymes, electrolytes, mucus, antibodies, and cells. Specific Uses : Diagnosis : Detects viral infections and certain bacteria (e.g., HIV, COVID-19). Genetic Testing : Provides DNA for genetic studies. Hormone level testing Measurement of cortisol, testosterone, estrogen levels. Drug and alcohol testing Detects the presence of drugs or their metabolites.

29. 8. Swab Samples Types: Throat Swab : Composition : Cells and secretions from the throat. Uses : Diagnoses throat infections like strep throat. Nasal Swab : Composition : Cells and mucus from the nasal cavity. Uses : Detects respiratory infections like influenza and COVID-19. Specific Uses : Diagnosis : Identifies infections and pathogens. Screening : For diseases and infections.

30. 9. Bone Marrow Samples Types: Aspiration : Composition : Liquid portion containing marrow cells. Uses : Diagnoses blood disorders like leukemia and anemia. Biopsy : Composition : Solid tissue core from the bone marrow. Uses : Provides detailed information on marrow structure and cellularity. Specific Uses : Diagnosis : Identifies hematologic malignancies and disorders. Assessment : Evaluates marrow function and disease progression.

31. 10. Amniotic Fluid Samples The study of amniotic fluid is performed primarily for three reasons: (1) to enable antenatal diagnosis of genetic and congenital disorders early in fetal gestation (15 to 18 weeks), (2) to assess fetal pulmonary maturity later in the pregnancy (32 to 42 weeks), and (3) to estimate and monitor the degree of fetal distress caused by isoimmunization or infection.

32. 10. Amniotic Fluid Samples Composition : Fluid surrounding the fetus, containing water, fetal cells, electrolytes, proteins, carbohydrates, lipids, and hormones. Specific Uses : Genetic Testing : Detects chromosomal abnormalities like Down syndrome. Infection Screening : Identifies infections affecting the fetus, and diagnose infections during pregnancy . Fetal Health : Monitors fetal development and lung maturity.

33. 11 . Synovial Fluid Composition: This viscous fluid is found in joint cavities, consisting of hyaluronic acid, lubricin, water, proteins, glucose, and white blood cells. Uses: Joint Aspiration (Arthrocentesis): Evaluates for infections, gout, rheumatoid arthritis, and other joint disorders.

34. 9. Pleural Fluid Composition: This fluid is present in the pleural cavity around the lungs (space between the lungs and chest wall), composed of water, proteins, glucose, and white blood cells. Uses: Analysis of pleural fluid helps diagnose pleuritis, tuberculosis, malignancies, and heart failure.

35. 10. Peritoneal Fluid Composition: Peritoneal fluid is found in the abdominal cavity and contains water, proteins, and immune cells. Uses: Peritoneal fluid analysis aids in diagnosing peritonitis, malignancies, and liver cirrhosis.

36. Pericardial Fluid Composition: Pericardial Fluid is Fluid from the pericardial sac around the heart, and contains Water, electrolytes, proteins, cells (white and red blood cells), and other solutes. Uses: - Diagnosis of infections (e.g., bacterial, viral, fungal). - Detection of malignancies. - Assessment of inflammation or bleeding.

37. Hair Samples Composition: Keratin, with traces of minerals, toxins, drugs, and other metabolites. Uses: Drug Testing: Detects long-term drug use or exposure. Hormone analysis. Toxicology: Identifying exposure to heavy metals and environmental toxins. Nutritional Deficiencies: Assessing deficiencies based on mineral content.

38. Nail Samples Composition: nails is composed primarily of keratin, with hair containing small amounts of melanin and trace elements. Uses: Toxicology Testing: Detecting long-term exposure to heavy metals or drugs. Fungal Infections: Diagnosing fungal infections in nails.

39. Sweat Samples Composition: Water, electrolytes (mainly sodium and chloride), urea, and lactate. Uses: - Diagnosis of cystic fibrosis through Measuring sweat chloride concentration. - Monitoring electrolyte imbalance. Metabolic Disorders: Screening for conditions that affect sweat composition.

40. Seminal Fluid Samples Seminal fluid or semen is a complex body fluid used to transport sperm or spermatozoa. It is analyzed routinely to evaluate infertility and to follow up after a vasectomy to ensure its effectiveness. Other reasons for analysis include the evaluation of semen quality for donation purposes and forensic applications (e.g., DNA analysis, detection of semen). Familiarity with the male reproductive tract and its various functions facilitates understanding of the physical, microscopic, and biochemical abnormalities that can occur in semen. Uses: Fertility Testing: Evaluating sperm count, motility, and morphology. Infection Diagnosis: Identifying infections affecting reproductive health.

41. Category Definition and commonly performed tests Hematology Hematology is the science that deals with the study of blood and blood forming tissues. Lab analysis for hematology deals with examining blood for detecting abnormalities and includes areas such as blood cell counts, cellular morphology, clotting ability of blood, and identification of cell types. Erythrocyte sedimentation rate Prothrombin time Differential white blood cell count Hematocrit Hemoglobin Platelet count Red blood cell count Reticulocyte count White blood cell count

42. Category Definition and commonly performed tests Clinical Chemistry Laboratory analysis in clinical chemistry determines the amount of chemical substances present in body fluids, excreta, and tissues. For example blood, urine, and cerebrospinal fluid. The most commonly evaluated clinical chemistry is blood chemistry. Alanine aminotransferase (ALT) Albumin Alkaline phosphatase (ALP) Amylase Aspartate aminotransferase (AST) Bilirubin Blood urea nitrogen (BUN) Calcium Carbon dioxide Chloride Cholesterol Creatinine Creatinine phosphokinase (CPK) Gamma glutamyltranspeptidase Globulin Glucose Inorganic phosphorus Lactate dehydrogenase (LDH) Potassium Pyroxene Sodium Total proteins Triglycerides Triiodothyronine uptake (T3 uptake) Uric acid

43. Serology and Blood banking Blood banking is serology deal with the study of antigen/antibody reactions and assessing the presence of disease or other potential pathologic substances. ABO blood typing Anti- nuclear antibody (ANA) Antistreptolysin O (ASO) C- reactive protein (CRP) Hepatitis tests HIV test Latex Pregnancy test Rh anti- body test Rh typing Rheumatoid factor (RF) Syphilis test (VDRL, RPR)

44. Urinalysis Urinalysis is the physical, chemical, and microscopic analysis of urine. Tests for physical analysis of urine includes: Color, Appearance, and Specific Gravity. Tests included in chemical analysis are: pH, Specific gravity, Glucose, Protein, Ketones, Blood, Bilirubin, Urobilnogen, Nitrite, Leukocytes. Tests included in microscopic analysis of urine are: Red blood cells, White blood cells, Epithelial cells, Casts, Crystals Microbiology Microbiology is the scientific study of microorganisms. It includes the identification and categorization of pathogens present in specimens taken from the body (such as urine, blood, throat, sputum, wound, urethra, vagina, cerebrospinal fluid). The following are examples of infectious diseases diagnosed by identifying pathogens present in a specimen: Candidiasis Chlamydia Diphtheria Gonorrhea Meningitis Pertussis Pharyngitis Pneumonia Streptococcal sore throat Tetanus Tonsillitis Tuberculosis Urinary tract infection

45. Parasitology Parasitology deals with the detection or presence of disease producing human parasites or their eggs present in specimens taken from the body (for example stool, vagina, blood). Examples of human diseases caused by parasites include: Amebiasis Ascariasis Hookworm Malaria Pinworms Scabies Tapeworms Toxoplasmosis Trichinosis Trichomoniasis Cytology In the lab, cytology deals with the detection or presence of abnormal cells. These tests include chromosomal studies and a Pap smear. Histology Histology is the microscopic study of form and structure of various tissues that make up living organisms. Lab analysis deals with the detection of diseased tissues and includes tissue and biopsy analysis.