HAEMATOLOGICAL EVALUATION OF ANEMIA Sitalakshmi S Professor and Head Department of Clinical Pathology St John s medical College, Bangalore
Learning Objectives Laboratory tests for the evaluation of anemia Classification of anemia Common causes of anemia in OB and Gyn practice Case discussion
What is anemia? Sign? Clinical finding? Laboratory finding? Disease? Pointer to a systemic disease?
The first step in any diagnosis: physical examination determining its cause A detailed medical, personal, and dietary history : Any family or personal history of anemia A history jaundice, or enlarged spleen Heavy menstrual bleeding in women Any signs of internal bleeding.
Of all the diagnostic tests available, complete blood count is one of the single most valuable tools in assessing the general health of the body. Provides a snap shot of the hematopoietic system at a specific point in time. It is a valuable indicator of disease, either local or systemic
Complete Blood Count (CBC) a panel of tests that measures RBC,WBC and platelets. For diagnosis of anemia, the CBC provides critical information on: the size, volume, and shape of RBC Hemoglobin Anemia is when Hb is < 11 g/dl for pregnant women < 12 g/dl for non-pregnant women
CBC The CBC includes quantitative evaluation of erythrocytes, leukocytes and platelets and Qualitative - microscopic examination of the blood film to detect morphological abnormalities that provide valuable insight to various disease conditions.
Components of CBC RBC parameters Platelet parameters WBC parameters - Scattergram Reticulocyte count
Parameters RBC parameters RBC count Hemoglobin Hematocrit MCV MCH MCHC RDW Reticulocyte Nucleated RBC WBC parameters WBC count Differential Platelet parameters Platelet count MPV PDW PCT
All the routine tests have been automated and new tests have been developed. Currently available automated analysers make it possible to process several hundreds of blood specimens a day.
All automated hematology analyzers in addition to enumerating the CBC results generate: red cell histograms platelet histograms and white cell histograms or scattergrams
The RBC and platelet histograms depict the cell sizing data in graphic form by plotting relative cell number versus size (volume) whereas scattergrams are two- dimensional or threedimensional plots of multiparameter data obtained for the DLC.
Red cell Indices mean cell volume (MCV) mean corpuscular hemoglobin (MCH) and mean cell hemoglobin concentration (MCHC) help us to classify an anemia as: regenerative (blood loss or hemolysis) or nonregenerative (production defect) often giving us insight to the etiology
Erythrocyte (RBC) Histogram RL RU PLT RBC 25-75 fl 200-250 fl RBC size: 80-95 fl RBC detection: between 25 and 250 fl Distribution curves are separated by flexible discriminators: RL & RU
MCV MCV (mean corpuscular volume) The average volume of RBC Hct = 10 (fl) RBC count (m/µl) e.g. Hct= 40% RBC=5.0 (m /µl) MCV= 40/5.0 10 = 80 fl NR= 80-96 fl
MCH MCH (mean corpuscular hemoglobin) The average content of Hb in average RBC. It is directly proportional to the amount of Hb and RBC size. Hb MCH = 10 (pg) RBC count (m/µl) e.g. Hb = 14 g/dl RBC = 4 (m/µl) MCH= 14/4 10 = 35 pg NR= 27-32 pg
MCHC MCHC (mean corpuscular hemoglobin concentration) Express the average concentration of hemoglobin per unit volume of RBC. It defined as the ratio of the weight of hemoglobin to volume of RBC. MCHC= Hb (g/dl) Hct (%) 100 (%) e.g. Hb = 14 g/dl Hct = 45 % MCHC 14/45 100 = 31% NR= 32-36%
RDW and HDW The new additions to the CBC profile which have useful clinical application. Red cell distribution width (RDW) an indicator of the degree of anisocytosis Hemoglobin distribution width ( HDW) - is a red cell parameter that measures anisochromia which along with MCV and RDW are useful in the differential diagnosis of microcytic anemia.
RDW RDW - coefficient of variation of the red blood cell distribution histogram. Quantitative measure of variation in RBC size (anisocytosis) RDW is elevated in: iron deficiency anemia RDW is normal in microcytic anemia of thalassemia.
RBC - Histogram Distribution Width RDW-CV 68.26% 100 % RDW CV is equivalent to 68,26 % of the distribution curve Reference range less than 16 % RDW-SD 100% 20% 200 250 fl 200 250 fl RDW SD standerd devation at 20 % of the distrubution curve Reference range: 37-46 fl.
Red cell indices in Anemia Anemia associated with thalassemia minor: low MCV, a normal RDW, and elevated HDW Iron deficiency anemia: Low MCV, an increase in both RDW and HDW Marrow regeneration as in haemolytic anemias : elevated MCV, RDW and HDW.
The severity of anemia is categorized by: Mild anemia Hb 9.5g/dl Moderate anemia Hb 7.0-9.5 g/dl Severe anemia Hb below 7.0 g/dl
Peripheral smear Reticulocyte smear
Reticulocyte Count Reticulocyte count is the percent of immature RBCs Normal levels 0.5-2% Corrected reticulocyte count compares anemic to non-anemic counterparts to assess response as reticulocyte count may overestimate response Corrected Reticulocyte Count = % Retic X HCT/45
Reticulocyte Correction Factor RPI = % reticulocytes X HCT/45 X 1/Correction Factor Hematocrit Correction Factor 40-45 1 35-39 1.5 25-34 2 15-24 2.5 Normal RPI =1 RPI < 2 Hypoproliferative anemia RPI greater than/equal 2 Hyperproliferative Disorder
CLASSIFICATION OF ANEMIAS Anemias may also be classified functionally into: Hypoproliferative (when there is a proliferation defect) Ineffective (when there is a maturation defect) Hemolytic (when there is a survival defect)
FUNCTIONAL CLASSIFICATION OF ANEMIAS
Kinetic Approach Decreased RBC production Lack of nutrients (B12, folate, iron) Bone Marrow Suppression Increased RBC destruction Inherited and Acquired Hemolytic Anemias Blood Loss
Morphological Approach Microcytic (MCV < 80) Reduced iron availability Reduced heme synthesis Reduced globin production Normocytic ( 80 < MCV < 100) Macrocytic (MCV > 100) Liver disease, B12, folate
MORPHOLOGICAL CLASSIFICATION OF ANEMIAS
NORMOCYTIC NORMOCHROMIC ANEMIAS
MICROCYTIC HYPOCHROMIC ANEMIAS
MACROCYTIC ANEMIAS
A 72 year old lady has the CBC findings shown.. Case 1
Case 1 What test would you order for this patient? A-Hemoglobin Electrophoresis B-Retic count C-Stool for occult blood D-B12 Assay E-Bone marrow biopsy Peripheral Blood smear: RBCs are hypochromic & microcytic
Case 1 Two questions: What is your diagnosis? What is the next step for this patient?
Answers Question 1 Likely Iron Deficiency Anemia Question 2 Colonoscopy Case 1
Iron Deficiency Anemia: Peripheral Smear Microcytosis &, Hypochromic RBCs
Iron Deficiency Anemia Low Retic Count High RDW Low iron level High TIBC Low ferritin
Degrees of Iron Deficiency
Tests for Assessing Iron Status Serum iron Total iron binding capacity (TIBC) Transferrin saturation = serum iron/tibc x 100 Serum ferritin Serum transferrin receptor (stfr)/serum ferritin [R/F ratio] Reticulocyte haemoglobin content Stainable iron in bone marrow
Case 2 A 28 year old lady G2P1 16 weeks gestation has become progressively more fatigued at the end of the day. This has been going on for months. In the past month she has noted paresthesia with numbness in the feet. A CBC demonstrates the findings shown.
Case 2 A peripheral blood smear (the slide is representative of this condition) shows red blood cells displaying macro- ovalocytosis and neutrophils with hypersegmentation.
Case 2 Which of the following tests would be most useful to determine the etiology? A. Hemoglobin electrophoresis B. Reticulocyte count C. Stool for occult blood D. Vitamin B12 assay E. Bone marrow biopsy
Case 2 Questions: What is the diagnosis from these findings? How do you explain the neurologic findings?
Answers: Question 1 Case 2 This is a macrocytic (megaloblastic) anemia. The neurologic findings suggest vitamin B12 deficiency (pernicious anemia). Question 2 The B12 deficiency leads to degeneration in the spinal cord (posterior and lateral columns).
Case 3 24 year old lady presented at 34 weeks of gestation with headache, vomiting and epigastric pain of acute onset. On examination she had anemia and jaundice. Investigations Hb 5.6g/dl TC 22000/cmm DC N 86 L 5 Bd 3 Myelo 2 meta 4 NRBC 7/100 WBC Platelet count 40.000/cmm
Peripheral smear: Case 3
Case 3 Biochemical investigations: Serum bilirubin 2.5 mg Conjugated 0.8 AST 786 IU/L ALT 1030 IU/L Alkaline phosphatase: 240 PT 13 sec C 12 sec INR 1
Case 3 HELLP syndrome Acute fatty liver of pregnancy
A Very Simple Classification of Hemolytic Anemias 1- Abnormalities of RBC interior a. Enzyme defects b. Hemoglobinopathies & Thalassemia M 2-RBC membrane abnormalities a. Hereditary spherocytosis, elliptocytosis etc b. Paroxysmal nocturnal hemoglobinuria c. Spur cell anemia 3- Extrinsic factors a. Hypersplenism b. Antibody : immune hemolysis c. Traumatic & Microangiopathic hemolysis d. Infections, toxins, etc Hereditary Acquired
HEMATOLOGIC Routine blood film Reticulocyte count Bone marrow examination Laboratory Evaluation of Hemolysis Extravascular Polychromatophilia Erythroid hyperplasia Intravascular Polychromatophilia Erythroid hyperplasia PLASMA OR SERUM Bilirubin Haptoglobin Plasma hemoglobin Lactate dehydrogenase URINE Bilirubin Hemosiderin Hemoglobin 0 0 0 Unconjugated, Absent N/ (Variable) Unconjugated Absent (Variable) 0 + + severe cases
Acute Myeloblastic Leukemia Aplastic anemia
A logical stepwise approach in the context of clinical presentation selection of appropriate laboratory tests to support the clinical suspicion Arrive at the correct diagnosis