Evaluation of Anaemia PDF

Evaluation of Anaemia Outline: What is Anaemia? Definition: ◼ refers to an inability of the body to supply tissues with adequate O2. ◼ In the U.S. & J.A., the Hb value is used to signify the presence or absence of anaemia ◼ In the U.K., the PCV (Hct) value is used to signify the presence or...

Evaluation of Anaemia Outline: What is Anaemia? Definition: ◼ refers to an inability of the body to supply tissues with adequate O2. ◼ In the U.S. & J.A., the Hb value is used to signify the presence or absence of anaemia ◼ In the U.K., the PCV (Hct) value is used to signify the presence or absence of anaemia ◼ Anaemia is neither a diagnosis nor is it a disease, but rather the symptom of an underlying disorder What is Anaemia cont’d? Clinically: ◼ Signs & symptoms associated with Anaemia include dizziness, pallor (of skin &/ mucous membranes), fatigue, shortness of breath etc… Laboratory-wise: ◼ Usually ↓ Hb, RBC Count & PCV values (decreased when compared to the relevant reference ranges for the sex, age group & population of the patient)  Reference Intervals(RI) used to evaluate Anaemia: ♀ ♂ Hb (12 – 16) g/dL Hb (14 – 18) g/dL PCV 3x’s the Hb above PCV 3x’s the Hb above (0.37 – 0.47) L/L (0.42 – 0.52) L/L RBC Count (4.2 – 5.4) x 1012/L RBC Count (4.7 – 6.1) x 1012/L RBC Indices: MCHC (32 – 36)g/dL ….normochromic MCH (27 – 31) pg normocytic MCV (80 – 100) fL Mild, Moderate, Severe anaemia Classification of Anaemia: ◼ Aetiology : the underlying cause resulting in the expression/presence of anaemia ❑ Nutritional deficiency (malabsorption vs. dietary lack) ❑ ↑ RBC destruction (< 100 - 120 dys.) ❑ ↓ RBC Production ❑ Haemorrhage (acute vs. chronic) ◼ Morphology: the appearance of the RBC’s in the on- going anaemia Aetiological Classification of Anaemia: 1. Nutritional Deficiency: Fe2+, Vitamin B12, Folate ❑ Dietary lack of any of these nutrients ❑ Malabsorptive process causing inability to digest the abovementioned nutrients from the diet ❑ eg. Iron Deficiency Anaemia 2. ↑ RBC Destruction: cell destruction before the normal 3mth. lifespan of the RBC (Haemolytic Anaemias) ❑ eg. G6PD Deficiency (intermediary in HMP Pathway) Aetiological Classification of Anaemia: 3. ↓ RBC Production: reduced output of mature RBC’s by the BM ❑ Nutritional deficiency (malabsorption/total dietary lack) ❑ Ineffective (haematopoiesis) erythropoiesis 4. Haemorrhage: ‘non-haematological’ loss of body’s RBC mass ❑ Acute eg. Stab wound (sudden; no chance for BM compensation) ❑ Chronic eg. GI Bleeding (extended BM compensation) Aetiological Classification of Anaemia: ◼ Depending upon the aetiology of the anaemia, then a particular: ❑ laboratory profile is expected and ❑ specific treatment options are required ❑ eg. If the aetiology of an anaemic process has been discovered to be due to a lack of Vitamin B12, then administering treatment with Fe pills is not necessarily the only/ideal treatment option that should be used ◼ Classifying an anaemic process is really to aid in accurate diagnosis & choosing the ideal treatment option Morphological Classification of Anaemia: ◼ RBC Indices: MCHC, MCH & MCV are used to describe the appearance of the RBC into 3 categories ❑ MCH – pg ❑ MCV – fL ❑ MCHC – g/dL  Morphological Classification of Anaemia cont’d: ◼ MCHC < RI = hypochromic ◼ MCHC > RI = RBC shape gets stuck in a spherical shape making the red cell lose surface:volume ratio and so [Hb] appears increased (> 36 g/dL) for the reduced volume of the RBC Spherocytes & microspherocytes Adapted from: N http://www.tyvh.gov.tw/CH/%C0%CB%C5 %E7%AC%EC-MT-web/SUB-03/03- 2234/2234-img/2234-P29.jpg N  RBC Membrane Structure with Defects: ◼ RBC membrane can withstand circulatory Hereditary Spherocytosis shear stress and numerous passages through the spleen during its lifespan Hereditary Elliptocytosis Adapted from: http://hemecoag.uthscsa.edu/wwwRedCell98/HOS%20Lecture/RBC.gif/27cysk2.gif Morphological Classification of Anaemia cont’d: ◼ MCH: < RI microcytic ◼ MCV: < RI ◼ MCH: N – > RI macrocytic ◼ MCV: > RI ◼ MCHC: < RI (hypochromic) ◼ MCHC: > RI (presence of spherocytes) Morphological Classification of Anaemia cont’d: ◼ The 3 Morphological Classifications of Anaemia are: ❑ Hypochromic / Microcytic ❑ Normochromic / Macrocytic ❑ Normochromic / Normocytic ◼ Each morphological classification has associated with it specific disorders ◼ Hence the occurrence of either 1 of the 3 categories will suggest a particular group of disorders; confirmatory tests that will rule out/rule in the disorders suspected are employed  Morphological Classification of Anaemia cont’d: ◼ Hypochromic Microcytic Anaemias can result from: ❑ Iron Deficiency Anaemia ❑ Sideroblastic Anaemia ❑ Thalassemia ❑ Anaemia of Inflammatory Disorders (chronic Haemorrhage) ◼ Normochromic Macrocytic Anaemias can result from: ❑ Vitamin B12 Deficiency ❑ Folate Deficiency ❑ Others …….you are to read & find out (for next class) Morphological Classification of Anaemia cont’d: ◼ Normochromic Normocytic Anaemias can result from: ❑ Read up and find examples of disorders that can cause this category of anaemia (for next class) ❑ Here’s a clue; subdivide this category with the Reticulocyte Count  Morphological Classification of Anaemia cont’d: ◼ Patient exhibited SOB, fatigue, tachycardia & there was evidence of koilonychia. From CBC: Hb, PCV & RBC Counts & MCHC, MCH & MCV are ↓. 1. These are hypochromic microcytes, the presence of which suggests the presence of one (or more) of 4 underlying disorders based upon the morphological classification of anaemias 2. Confirmatory Tests that will test for these 4 disorders are then employed. Adapted from: https://www.stu.qmul.ac.uk/SMD/kb/pathology/introcoursepics/images/hypocrom.jpg  Normal BM Response in Anaemia: ◼ BM will increase the rate of erythropoiesis to compensate for a peripheral blood cytopenia (↓RBC’s) ❑ ?BM Cellularity ; ?M:E ratio ❑ ? Reticulocyte Count ◼ For this reason, signs & symptoms of anaemia may be ‘staved off ’ even though someone has ↓ Hb, PCV &/ RBC Count values = truly anaemic but not yet clinically anaemic ◼ When the patient exhibits signs & symptoms of anaemia = clinically anaemic (BM is compensating but can no longer ‘stave off ’ symptoms; person becomes symptomatic of the anaemia)  Diagnosis of Anaemias: Expected results from Routine Laboratory Tests ◼ ↓ Hb, PCV (or Hct) & RBC Count* ❑ Indicates the presence of anaemia ◼ RBC Indices: varies ❑ Morphologically classifies the anaemia From CBC ❑ ↓ MCHC, MCH & MCH = ?? ❑ ↑ MCH, MCV & Normal MCHC = ?? ❑ Normal MCHC, MCH, MCV = ?? ◼ Slide Analysis: ❑ check the results from Indices here From the Wright’s ❑ only way to check the appearance of the blood cells eg. stained shape (?poikilocytosis), presence of Howell Jolly bodies smear * Values vary with Thalassemias Diagnosis of Anaemias: Expected results from Routine Laboratory Tests ◼ Reticulocyte Count ↑ ❑ measures the rate of erythropoiesis All the information provided by the: ❑ clinical summary (physician) ❑ CBC (Hb/PCV/RBC Count + RBC Indices) ❑ Wright’s stained smear ❑ Reticulocyte Count will suggest which confirmatory test to choose. Treatment Options in Anaemia: 1. Will depend LARGELY on the aetiology of the anaemic process ◼ Specific treatment is ideal: ❑ eg. Iron therapy in IDA, B12/Folate complexes in B12/Folate deficiencies 2. Palliative care can be administered for relief of pain (analgesics) or symptoms ◼ RBC transfusions (↑ RBC mass) ◼ Non-specific supportive therapy (to promote erythropoiesis eg. Iron pills, B-complex vitamins, EPO)