DOM Morning report Week of 8

1. DOM Morning report Week of 8/31-9/4

2. Objectives Review the basic approach to anemia including categorization and lab evaluation Discuss hemolytic anemia and the mechanisms of hemolysis Define and discuss autoimmune hemolytic anemia (AIHA) Specifically, Warm AIHA, Cold Agluttinin Syndrome

3. Anemia Defined as a reduction in one or more of the major RBC measurements: Hgb: measures the concentration of the major oxygen carrying pigment in whole blood Hct: percent of a sample of whole blood occupied by intact RBCs RBC Count: number of RBCs contained in a specified volume of whole blood All factors are dependent on the RBC mass and the plasma volume

4. Signs and Symptoms of Anemia Dependent on the degree of anemia, the rate at it evolved, and the oxygen demand Normally, RBCs carry oxygen linked to Hgb from the lung to tissue capillaries, where oxygen is released Symptoms result from decreased oxygen delivery or acute blood loss (hypovolemia) Compensatory mechanisms allow one to tolerated lower levels of Hgb/Hct Increase in stroke volume, HR (? increased CO) Enhanced oxygen extraction by the tissues Exertional dyspnea, dyspnea at rest, fatigue Signs and symptoms of a hyperdynamic state: Bounding pulses, palpitations, “roaring in the ears”

5. Approach to Anemia Classification: Kinetic Approach –mechanism responsible Decreased RBC production Increased RBC destruction Blood Loss Morphologic Approach – alteration in RBC size Macrocytic Normocytic Microcytic

6. Kinetic Approach Decreased RBC Production Lack of nutrients (Fe, B12, Folate) due to diet, malabsorbtion Bone Marrow Disorders Bone Marrow Suppression Drugs, chemotherapy, radiation Low levels of trophic hormone levels which stimulate RBC production Epo, Thyroid Hormone, Androgens Chronic disease/inflammation Causes decreased Fe absorbtion from GIT, decreased Fe release from macrophages, reduction of Epo Malabsorbtion: sprue, pernicioius anemia; Blood Loss: IDA ACDz/inflammation: reduced availability or Fe 2/2 decreased absorption from GIT and decreased release from macrophagesMalabsorbtion: sprue, pernicioius anemia; Blood Loss: IDA ACDz/inflammation: reduced availability or Fe 2/2 decreased absorption from GIT and decreased release from macrophages

7. Kinetic Approach Increased RBC Destruction Inherited and acquired hemolytic anemias Inherited: Hereditary Spherocytosis, sickle cell disease, thalassemia Acquired: AIHA, TTP-HUS, malaria Blood Loss One of the most common causes of anemia Not only lose RBCs, but also the Fe in these cells, which leads to Fe deficiency

8. Morphologic Approach Macrocytic Reticulocytosis Drugs interfering with nucleic acid synthesis Abnormal nucleic acid metabolism of erythroid precursors Abnormal RBC Maturation ETOH abuse, liver disease, hypothyroidism Normocytic Microcytic Reduced iron availability Reduced Heme synthesis Reduced globin production Increased MCV is a normal characteristic of reticulocytes Reduced fe availability: IDA, ACD, Cu deficiency Reduced heme synthesis: lead poison, sideroblastic anemia Reduced globin production: thallasemia, HgbopathyIncreased MCV is a normal characteristic of reticulocytes Reduced fe availability: IDA, ACD, Cu deficiency Reduced heme synthesis: lead poison, sideroblastic anemia Reduced globin production: thallasemia, Hgbopathy

9. Differentiating Microcytic Anemias

10. Evaluation of the Patient Look for evidence of : Bleeding Hemolysis BM suppression Iron deficiency Vitamin deficiency History: ethnicity, country of origin, medications, h/o blood transfusion, liver disease, chemicals exposure FH: h/o anemia or iron use PE: pallor, jaundice, LAD, HSM, bone pain Bone pain can signify expansion of marrow due to infiltrative diseaseBone pain can signify expansion of marrow due to infiltrative disease

11. Lab Evaluation CBC Reticulocyte Count: High: hemolysis or blood loss Low: deficient production of RBCs (reduced marrow response to anemia) RBC Indices: MCV – mean corpuscular volume (Hct/RBC) MCH – mean corpuscular Hgb (Hgb/RBC) MCHC – mean corpuscular Hgb concentration (Hgb/Hct)

13. Hemolytic Anemia Anemia due to shortened survival of circulating RBCs (Normal: 110-120 days) Hemolysis <100 days With intact bone marrow: Anemia ? Compensatory increase in Epo secretion ? Enhances RBC production (reticulocytosis) ? Reduces degree of anemia This is most commonly seen with hemolytic anemia, but not specific to hemolysis (can also be seen with acute blood loss)

14. Reticulocyte Count Uncorrected reticulocyte count Absolute reticulocyte count Reticulocyte % X RBC count Corrected reticulocyte count Accounts for reticulocyte maturation time (RMT) The reticulocyte can spend up to 2.5 days in the peripheral circulation Absolute retic count / RMT (~2.5 days) Reticulocyte production index Corrects for degree of anemia and RMT RPI: reticulocytes (percent) X (Hct/45) X (1/RMT)

15. Causes of Hemolysis - Intrinsic Generally, a hereditary disorder Remember, the mature RBC has lost its nucleus, mitochondria, and RNA, leaving Hgb, RBC membrane Intrinsic hemolysis is caused by defects in Hgb, RBC membrane or metabolic factors needed to generate ATP Examples Thalassemia (defect in alpha or beta globin chains) Spherocytosis (missing RBC membrane proteins) G6PD deficiency (abnormality in reducing power (NADPH))

16. Causes of Hemolysis - Extrinsic Acquired disorder Causes include: Ab directed against RBC membrane components AIHA, delayed transfusion reaction Stasis/trapping/destruction in spleen (hypersplenism) Trauma Prosthetic heart valve Exposure to compounds with oxidant potential Sulfonamide in those with G6PD Destruction of RBC by pathogens Malaria, babesiosis

17. Site of Hemolysis Dependant on the severity and type of cell alteration (alteration in RBC membrane) Severe damage ? immediate lysis in the circulation (INTRAVASCULAR) Less severe damage ? cell destruction is via the monocyte-macrophage system in the liver, spleen, BM, lymph node (EXTRAVASCULAR)

18. Intravascular Hemolysis Intravascular hemolysis ? Release of Hgb into the plasma Free Hgb binds to haptoglobin ? Hgb-haptoglobin complex is taken up by liver ? Decrease in plasma haptoglobin Free Hgb breaks down to alpha-beta dimers ? filtered by glomerulus ? Hemoglobinuria

19. Intravascular Hemolysis Causes: Direct trauma Bongo drummers, “foot strike hemolysis” Shear stress Mechanical heart valve Heat damage Complement-induced lysis Paroxysmal cold hemoglobinuria Osmotic lysis Lysis from bacterial toxins Clostridium

20. Extravascular Hemolysis Damaged RBCs are destroyed by liver (receives a larger portion of the cardiac output) and spleen Spleen contains cords of Billroth, which end blindly (unlike other vascular channels in body) RBCs must deform to pass through 2-3 micron slits in the wall of the cords in order to get back into circulation RBCs unable to pass are phagocytosed by the monocyte-macrophage system Degraded into biliverdin, iron, carbon monoxide

21. Features of Hemolysis Rapid fall in Hgb Increased LDH, decreased Haptoglobin Jaundice (elevated indirect bilirubin) Splenomegaly H/o pigmented gallstones Abnormally shaped RBCs Reticulocytosis Reticulocytes: blue tint (polychromatophilia), larger than a mature RBC, irregular borders, lack of central pallorReticulocytes: blue tint (polychromatophilia), larger than a mature RBC, irregular borders, lack of central pallor

22. Peripheral Smear Spherocytes Fragmented RBCs Schistocytes, helmet cells Microangiopathic hemolytic anemia Acanthocytes (spur cells) Liver disease Blister or “bite” cells G6PD

23. Peripheral Smear RBCs with inclusions Teardrop RBCs Red Cell “ghosts” Hemolyzed RBCs that reform, but have lost all internal components, leaving only the membrane Indicates intravascular hemolysis

24. Labs LDH: elevated Indirect bilirubin: elevated (due to catabolism of Hgb) Haptoglobin: decreased Binds to Hgb and taken up by liver In a series of reports: Elevated LDH, low Haptoglobin was 90% specific Normal LDH, Haptoglobin >25 was 92% sensitive for ruling out hemolysis Reticulocyte Count: elevated Normal is 0.5-1.5% Anemia leads to increase Epo production leading to a reticulocytosis (4-5% increase above baseline) Positive Direct Antiglobulin Test (Coombs)

25. Immune Hemolytic Anemia IgG and/or IgM bind to RBC surface Ag and initiate RBC destruction via Complement system Reticuloendothelial system AutoImmune Hemolytic Anemia Production of Ab directed against self RBCs

26. Autoimmune Hemolytic Anemia Warm AIHA Cold Agglutinin Syndrome Paroxysmal Cold Hemoglobinuria Mixed Type AIHA Drug Induced AIHA *Idiopathic Secondary causes Lymphoproliferative disorders Autoimmune disorders Viral Infection Immunodeficiency Drugs Types Causes

27. Warm AIHA 48-79% of AIHA Incidence increased at 40yrs 2:1 Female to Male ratio No racial predilection Idiopathic vs Secondary Causes CLL, Hodgkins, non-Hodgkins, Waldenstroms Autoimmune, non-lymphoid neoplasms, immunodeficiency, viral illnesses Typically present with anemic signs and symptoms These symptoms may precede and underlying illness by months to years Non-lymphoid neoplasms: ovarian dermoid cysts, teratoma, kaposi’s sarcoma, carcinomaNon-lymphoid neoplasms: ovarian dermoid cysts, teratoma, kaposi’s sarcoma, carcinoma

28. Warm AIHA - Labs Elevated MCV (reflecting reticulocytosis) Mild leukocytosis with neutrophilia Blood smear: Polychromasia, macrocytosis, spherocytes, nucleated RBCs Elevated LDH and indirect bilirubin Haptoglobin typically low Because it is an acute phase reactant, it can also be normal or elevated in mild disease

29. Warm AIHA – DAT (direct Coombs) Detects Ab on the RBC surface Pt’s RBCs are washed then reacted with monoclonal Ab against various Ig (IgG) and C3 Warm autoantibodies react at warmer temperatures (~37° C) 95% of Warm AIHA will have a positive DAT Negative tests due to: IgG quantity too low for detectable threshold IgA autoantibodies IgM autoantibodies

30. Warm AIHA - Treatment Folic Acid Further treatment depends on severity *Steroids – 1mg/kg/day Splenectomy Removes source of extravascular hemolysis Removes a site of Ab production Cytotoxic drugs Cyclosporine Azathiaprine

31. Cold Agglutinin Syndrome (CAS) 16-32% of AIHA Most commonly in the 7th decade Slight female predominance Idiopathic or secondary (most commonly infection or lymphoproliferative disorders) RBC clumping (leads to artifactual elevation in MCV and decreased RBC count) React most strongly at 0-4°

32. CAS - Treatment Avoidance of cold exposure Move to a warmer climate Immunosuppression (cyclophosphamide) Plasmapheresis can temporarily help Compared to warm AIHI. . . Steroids are not beneficial Splenectomy is not beneficial Extravascular hemolysis typically occurs in liver

33. MKSAP #29 A 27y F with a 2yr history of systemic lupus erythematosus is evaluated for new-onset fatigue and shortness of breath of 10 days’ duration. Her medications include hydroxychloroquine and ibuprofen. The medical history is otherwise noncontributory. On physical exam, the pulse is 109/min, respiration rate is 14/min, and blood pressure is 130/80mmHg. Other than pale conjunctivae and pallor, the physical exam is normal. Laboratory studies indicate a hemoglobin of 5.2 g/dL compared with a normal value 3 months ago. The current peripheral blood smear is shown.

34. MKSAP #29 Which of the following is the most appropriate initial treatment for this patient? A. Oral ferrous sulfate B. Corticosteroid therapy C. Erythropoietin D. Plasmapheresis

35. MKSAP #29 Peripheral smear shows polychromasia and spherocytes Polychromasia is from reticulocytosis Younger RBCs appear more bluish-grey Spherocytosis occurs after membrane removal by macrophages in the spleen First line treatment for AIHA is steroids Fe and Epo are used for IDA Plasmapheresis is used for TTP (microangiopathic hemolytic anemia)

36. Follow Up of Patient Heme Consult Recommends: Folic Acid 1mg/daily Prednisone 100mg/d CT-CAP to look for underlying lymphoproliferative disorder CT-CAP: right axillary LAD, right inguinal LAD, ill defined lesion in the left hepatic lobe