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Dr Maliha Sumbul 4 th April 2009

Pathophysiology of diseases and Laboratory service ( A correlation ). Dr Maliha Sumbul 4 th April 2009. FEW CASES. Symptoms: Fatigue Dyspnoea Palpitations Blackouts Headache Anorexia Bowel disturbance. Signs: Pallor

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Dr Maliha Sumbul 4 th April 2009

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  1. Pathophysiology of diseases and Laboratory service ( A correlation ) Dr Maliha Sumbul 4th April 2009

  2. FEW CASES

  3. Symptoms: Fatigue Dyspnoea Palpitations Blackouts Headache Anorexia Bowel disturbance Signs: Pallor Spoon-shaped nails (koilonychia) Tachycardia Cardiac enlargement Heart failure (later stages) CASE 1:

  4. Lab Tests to order ? • Complete blood count Hb: 6.0 gm/dl RBC: 3.0 X 1012/l MCV: 65 fl MCH:20 pg WBC: Normal Platelets: Increased • Peripheral smear shows Microcytic, hypochromic anaemia, anisocytosis, poikilocytosis, target cells • ESR Increased • Stool D/R (Occult blood) • Positive

  5. MCV: (fl) Average size of Rbc Hct in % / RBC count x 10 MCH (pg) Hb in gm/dl / RBC count x 10 MCHC: (gm/dl) Hb in gm/dl / Hct x 100 Normal RBC Indices MCV: 80–100 fl MCH: 27–31 pg MCHC: 31–36% or g/dL RDW: 12–15%

  6. MCV • Normal range: 80 – 100 Fl • MCV= Hct in fL / RBC in L • If: Hct = 45% (or 0.45 L) Rbc: 5.0 x 1012 / L 1 ul=109 fL 1 L= 1015 fL • Then: MCV = 0.45 X 1015 fL/ L 5.0 X 1012 / L = 0.09 X 103 fL = 90 Fl Therefore, the formula: MCV = Hct X103 Fl RBC (/L)

  7. Hb in g/dl MCH • Normal Range: 27 – 31 pg • Formula: MCH = Hb in L / RBC in L • If: 1 g = 1012 pg 1 L = 10 dl • Then: MCH = Hb x 10 x 10 12 pg/L • If: Hb= 15.0 g/dl, RBC= 5.0 X 1012 /L • Then: MCH = 15 X 1013 pg/L 5.0 X 1012/L = 15 X 10 pg/L 5.0 /L = 30 pg Therefore the formula: MCH = Hb ( g /L) pg RBC (/L)

  8. MCHC • Normal range: 31 – 36 g/dl or % • MCHC= Hb in g/dl X 100 (TO CONVERT TO %) Hct • If Hb = 15.0 g/dl Hct = 45% or 0.45 • Then: MCHC = 15.0 g/dl X 100% 45 g/dl = 0.333 X 100% = 33.3 %

  9. Further tests to order ? • Reticulocyte count • Serum Iron • Total Iron Binding Capacity (TIBC) • Ferritin level • Bone marrow for Iron stores • Radiological investigations (sigmoidoscopy, barium enema)

  10. Diagnosis ? Iron-deficiency anaemia IRON IS VITAL FOR ALL LIVING ORGANISMS (oxygen transport, DNA synthesis , electron transport…………………..) Causes: • Dietary deficiency • Malabsorption • Blood loss – commonest cause ( Menorrhagia > 80 ml/cycle) or GI Bleeding Proximal small intestine (Iron abs site) Hookworm infestation

  11. Peripheral blood smear demonstrating changes with iron deficiency anemia. Note the increased zone of central pallor and the more irregular shapes of the RBC's

  12. Symptoms: SAME AS BEFORE Signs: SAME WITH THE EXCEPTION OF KOILONYCHIA CASE 2: HISTORY Vegan

  13. Tests to order ? • CBC: Hb: 8.0 gm/dl RBC: 3.0 X 1012/l MCV: 110 fl MCH: 32 pg WBC: 2.0 Platelets: 90,000 • Peripheral smear: Macrocytic, normochromic, Oval macrocytes, Hypersegmented neutrophils, Nucleated red blood cells • ESR:Increased

  14. Further tests to order ? • Reticulocyte count • Vitamin B12 level • Red cell folate level (RBC folate more reliable than serum folate) • Bone marrow biopsy – Megaloblastic changes (out of pahse cytoplasmic and nuclear maturation as nuclear maturation is slow)

  15. Diagnosis ? Parietal cells Stomach –IF (AUTOIMMUNE) • Megaloblastic anaemia • B12 deficiency: Pernicious anaemia Post-gastrectomy (No IF) Poor diet (Vegans) Ileal diseases (site of abs) eg: Crohn’s disease Diphyllobothrium latum worm (Fish tapeworm) • Folate deficiency: Dietary deficiency ( alcoholics) Increased need (pregnancy, malignancy) Malabsorption (coeliac disease, tropical sprue) Drugs ( phenytoin, trimethoprim)

  16. Vitamin B12 - member of the vitamin B complex. - contains cobalt, also known as cobalamin. - exclusively synthesised by bacteria - found primarily in meat, eggs and dairy products. Primary functions - formation of red blood cells and the maintenence of a healthy nervous system. - necessary for the rapid synthesis of DNA during cell division. If B12 deficiency occurs, DNA production is disrupted and abnormal cells called megaloblasts occur. This results in anaemia • Folic acid: - Anaemia may also be due to folic acid deficiency, necessary for DNA synthesis. - Foods: Fortified breads and grains, Spinach, Orange juice,Green peas, okra……….

  17. Symptoms: Fever-high grade Body aches Constipation or diarrhoea Abdominal pain Signs: Splenomegaly Rose spots (rashes) on trunk Dehydration Case 3:

  18. Rose spots

  19. Lab tests ? CBC: Normal ESR: Increased Serology: Widal test: Negative Typhidot IgG: Negative, IgM: Positive

  20. Further tests to order ? • Blood Culture: Positive (Salmonella typhi) • Blood ….1st week • Faeces & Urine .…2nd week • Bone marrow culture…..highest yield

  21. Diagnosis ? • Enteric fever (Typhoid) Salmonella infection - Bacteria • PATHOPHYSIOLOGY: Complex • Asymptomatic incubation - Bacteria invade macrophages and invade RE system • 1st week of symptomatic disease – High fever with bacteremia • 2nd week: Rose spots, abd pain, splenomegaly • 3rd week: Intense inflammatory response in Peyer’s patches – necrosis, perforation, haemorrhage • Untreated - sepsis leading to death • Remember: WIDAL TEST IS UNRELIABLE

  22. The Peyer's patches are enlarged, elevated, hemorrhagic and necrotic Terminal ileum and cecum in typhoid fever

  23. Symptoms: Headache Weakness Body aches Fever attacks – every 3rd day ( 1, 3, 5) -Sudden coldness - rigor for 1 hour - high fever - flushing - vomitting - Drenching sweats Signs: Pallor Yellow eyes Enlarged Liver/Spleen Black urine Altered consciousness CASE 4:

  24. Tests to order ? • CBC: Hb 7.0 g/dl MCV/MCH: Normal WBC: Normal Platelets: 80,000 (low) • Thick and thin smears: Plasmodium falciparum (all stages) • ICT MP: Positive Blood Test 50 parasites/ul 98% Specificity (Thick and Thin films) Gold Standard for malaria diagnosis !

  25. RDT AMRAD ICT FOR Pf HRP-2 DETECTION > 100 p/ul-96% sensitivity 99% specificity

  26. Further tests to order ? • Urinalysis: RBCs present • U&E: Urea Creatinine Sodium • Blood culture: Negative • Blood Glucose: Normal (may be low in severe cases)

  27. Diagnosis ? • Malaria – P falciparum Most damaging human parasite ! Parasite enters RBCs multiply Red cell destruction characteristic chills and fever Red blood cells primary carriers of oxygen P.vivax invades predominantly reticulocytes and so has a built-in ceiling, but P.falciparum can invade all ages of RBCs.

  28. MALARIA VECTOR Image of a typical anopheline mosquito at rest showing the abdomen at an angle to the surface Culicines maintain their abdomen in a parallel position

  29. TRANSMISSION OF MALARIA • Bite of female “anopheles” mosquito. • Use of contaminated needles. • Through blood transfusion. • By congenital means.

  30. LIFE CYCLE

  31. One of the leading causes of disease and death in the world • 300-500 million new cases every year • 1.5-2.7 million deaths worldwide (WHO)

  32. Sickled red blood cells-resistant to malaria

  33. World map showing distribution of malaria - W.H.O. 1991

  34. HealthNet International Malaria Control Programme (WHO)

  35. Cinchona tree MALARIA A complex but curable and preventable disease. Early detection and adequate treatment saves life. Prevention is better than cure !!! -Vector control -Exposure prophylaxis -Chemoprophylaxis ? Resistance .

  36. MALARIA STAINING AND pH

  37. Specimen 0702PA1 (Thick film, Fields stain) - 349 : Plasmodium (CORRECT) - 04 :Another Parasite (INCORRECT) - 95 : NEGATIVE (20%) Specimen 0702PA2 (Thin film, Giemsa stain- pH 7.2) - 331 : P.vivax (CORRECT) - 69 : Other Plasmodium - 04 : Another parasite - 08 : Unable to speciate - 60 : NEGATIVE (13%) UK NEQASUnited Kingdom National External Quality Assessment Scheme

  38. REAL CASE PRESENTATIONS

  39. Hx: A thin film 27 Yr old female backpacker, with a recent history of trekking through Northern Thailand and high fever

  40. DIAGNOSIS ? • Salient features -Numerous fine ring forms -Double chromatin dots -Marginal forms -Red cells are not enlarged This is a typical Plasmodium falciparum infection

  41. Hx: Aches and pains, with fever. ? Glandular fever ?Malaria

  42. DIAGNOSIS? • Salient features: -Enlarged red cells -Thicker(signet ring) forms -Schuffner’s dots • Typical Plasmodium vivax infection

  43. Hx: Thick film prepared from a 32 yr old male, recently returned from Vietnam

  44. DIAGNOSIS ? • Salient features: -Numerous ring forms of Plasmodium seen ( arrows) -Note size of neutrophils (for comparison) Malaria is present (Thin films required for species identification)

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