| What is pyruvate kinase deficiency? | Caused by gene mutation affecting activity of pyruvate kinase (last enzyme in glycolysis turning phosphoenol pyruvate to pyruvate making ATP)
Auto recessive, intrinsic to RBC, extravascular (spleen), since no pyruvate kinase, 1,3-bisphosphoglycerate will transform to 2,3-DPG which offsets anemia by right shifting the oxygen saturation curve |
| How is pathophysiology of pyruvate kinase deficiency? | RBC only glycolysis (no mitochondria), PK deficiency little or no ATP/NADH production, ATP deficiency affects Na+/K+ ATPase leading to osmotic instability and misshapes RBCs clear them in spleen (extravascular hemolysis).
NADH deficiency decrease reducing power required to convert methemoglobin (Hb-Fe3+ to Fe2+) because of distal block, 2,3-DPG is increased, binds to Hb and alters its conformation (shifts OSC to right) |
| How is dx of pyruvate kinase deficiency? | In childhood as chronic hemolytic anemia, serum methemoglobin increased, rare disease
Echinocytes are RBCs that had their membranes damaged due to dysfunctional Na+/K+ ATPase seen in microscopy |
| What is sickle cell anemia? | Point mutation in beta globin gene leading to sickle hemoglobin, inherited group of disorders characterized by presence of hemoglobin S (sickle cell anemia/beta thalassemia/SC disease..)
Auto recessive, hallmarks are vaso-occlusive phenomena and hemolytic anemia.
Valine (GTG) for glutamic acid (GAG) 6th amino acid substitution in beta globin, the resulting tetramer becomes poorly soluble when deoxygenated |
| How is manifestation of sickle cell anemia? | Acute manifestations
Infection, anemia and vaso-occlusion (life-threat)
Infection (encapsulated bacteria), acute vasooclusion pain may be accompanied with other complications (stroke, renal infarction, acute chest syndrome, priapism, bone infarct, osteomyelitis (salmonella)
Complications related to pregnancy.
Chronic manifestations
chronic organs ischemia and infarction exacerbated with iron overload
Chronic pain, seizure disorder, pulmonary HTA, asthma, hypoxemia, renal impairment and HTA, osteoporosis (bone infarct), cardiamyopathy (diastolic), hepatic injury, delayed puberty, reduced growth, chronic leg ulcers, proliferative retinopathy
Spleen frequently affected (infarcted in childhood (autosplenectomy) recommended Abx and vax |
| How is sickle cell disease dx? | HPLC, Hgb electrophoresis (cellulose acetate, citrate agar), DNA testing may be useful |
| What are subtypes of SCD? | . |
| How is tx of SCD? | Pain management, preventive measures (vax, BP control, nutritional), hydroxyurea (hydroxycarbamide), transfusion, stem cell transplant, iron chelating agent (iron overload) |
| What is polycythemia? | Increase in hemoglobin concentration makes blood more difficult to pump around the body, more viscous and complications include blood clot, tiredness, lethargy, and pruritis |
| How is classification of polycythemia? | Primary polycythemia (myeloproliferative disorder w/increased RBC mass (clonal proliferation))
Secondary (increase in erythropoietin [lung disease, smoking, attitude, tumor producing alot of erythropoietin])
Relative polycythemia (Hemoconcentration, elevation of Hb/Hct due to decrease in plasma volume alone. |
| What is Polycythemiavera polycythemia? | Splenomegaly, thrombocytosis/leukocytosis, thrombotic complications, erythromelalgia/pruritis.
EPO level decrease, JAK2 V617F mutation +ve |
| How is management of PV? | Phlebotomy, hydroxycarbamide or JAK2 inhibitors.
Secondary PV is best treated by correcting the underlying cause and using phlebotomy if needed |
| What are hemolytic anemia types? | Warm autoimmune hemolytic anemia (AIHA), paroxysmal cold hemoglobinuria, cold agglutinin disease, hemoglobinopathies, drug-induced hemolytic anemia, RBC membrane defects, RBC enzymatic defects, microangiopathic hemolytic anemia (MAHA) (TTP) (HUS) (DITMA)
Hemolysis associated with blood transfusion, paroxysmal nocturnal hemoglobinuria (PNH) |
| What are causes of hemolysis? | Intrinsic or extrinsic to RBCs (intracorpuscular vs. extracorpuscular defects), inhertited or acquired, acute or chronic, immune destruction (AB) or non-immune mechanism, intravascular vs extravascular (in vasculature or in reticuloendothelial macrophages in liver and spleen), most of inherited conditions are intracapsular and most of hemolysis by an immune mechanism is extravascular.
Reticulocytosis requires adequate iron and vitamins (B12, folate) for RBC production.
Normally functional bone marrow and adequate EPO production |
| What are extravascular causes of destruction of RBCs? | . |
| What are the causes if intravascular destruction of RBCs? | . |
| What is autoimmune hemolytic anemia (AIHA)? | Due to presence of warm agglutinins, almost always due to IgG react w/protein antigens on the RBC surface at body temperature, for this reason they are called warm agglutinins (seldom directly agglutinate RBCs) |
| What are etiologies of AIHA? | Most cases unknown, minority of cases associated with other disorder include (viral infection [children], autoimmune disorders [SLE], lymphoproliferative diseases [chronic lymphocytic leukemia], disorders of immune deficiency/regulation [common variable immunodeficiency], drugs [penicillin, methyldopa], allogenic blood transfusion/ABO-incompatible hematopoietic cell transplantation |
| What are clinical manifestations of AIHA? | Small amount may be asymptomatic/slightly anemic.
If severe hemolysis and sudden onset, symptoms may be those of severe degrees of cardiac compensation including heart failure, arrhythmia, chest pain, medical emergency.
Physical exam reveals pallor, jaundice, moderate splenomegaly |
| What are labs of AIHA? | • Complete blood count with red blood cell indices (eg, MCV, MCH, MCHC), reticulocyte percentage, and examination of the peripheral blood smear
• Tests for hemolysis, including indirect bilirubin, lactate
dehydrogenase, and haptoglobin
• Direct antiglobulin (Coombs) testing, including testing for both IgG and C3 on the red cell surface
• Testing for specificity of the antibody for antigens identified on red blood cells
• Anemia may be severe,↑MCHC (spherocytosis), ↑MCV (reticulocyte)
• ↑indirect bilirubin, ↑lactate dehydrogenase, and ↓haptoglobin.
• The peripheral blood smear; spherocytes, polychromatophilic (retic)
• DAT, direct antiglobulin test (Coombs); 97- 99 % of pt will exhibit apositive result with anti-IgG, anti-C3, or both (on the surface of RBC). |
| How is treatment of AIHA? | Initial tx of symptomatic start GCs, acute onset of severe hemolysis w/symptomatic anemia in pt with cardiac disease, immediate red cell transfusion may be needed
Second-line treatment for symptomatic pt not responding to GCs is elective splenectomy/rituximab |
| What is cold agglutinins AIHA? | IgM antibodies recognize RBC antigens at temperatures below normal core body temperature.
Infections (mycoplasma pneumonia and EBV (mono)), autoimmune disorders and lymphoid/plasma cell malignancies (B cell NHL, CLL, Waldenstrom macroglobulinemia) |
| How is dx of cold agglutinins AIHA? | • Evidence of hemolysis (eg, high reticulocyte count, high LDH, high indirect bilirubin, low haptoglobin)
• Positive direct antiglobulin (Coombs) test for C3d
• Cold agglutinin titer of ≥64 at 4°C
• Blood smear, RBC agglutination |
| How is management of AIHA? | • Cold-induced symptoms –avoidance of cold temperatures, if hospitalized (keep things warm) IVF fluid, blood transfusion etc..
• Anemia –if severe or symptomatic anemia, transfusions can be given.
• Underlying disorders –individualized according to the specific disorder and patient's clinical status. If lymphoproliferative disorder (clonal) Rituximab
• Glucocorticoids and splenectomy are not effective in the majority of patients |
| What is paroxysmal cold hemoglobinuria? | • Donath-Landsteiner hemolytic anemia
• Autoantibody (IgG) binds to the red blood cell (RBC) P antigen in the cold and fixes complement.
• Upon warming, the antibody dissociates and complement lyses the RBCs, leading to intravascular hemolysis.
• Induced by acute infections (often viral), chronic syphilis, or states of immune dysregulation |
| What is presentation of paroxysmal cold hemoglobinuria? | • Signs and symptoms related to intravascular hemolysis (back or abdominal pain, weakness, nausea or vomiting, fever or chills, and/or dark or red urine), typically are self-limited and correlate with cold exposure.
• Positive direct Coombs test for complement. Initial testing will show anemia, low haptoglobin, high (LDH) and bilirubin, and free hemoglobin in serum and urine.
• Patients with these findings can be tested for the Donath-Landsteiner antibody |
| How is management of paroxysmal cold hemoglobinuria? | • Management of the acute episode is supportive.
• It is important to avoid all cold exposures including cold ambient temperature, cold surfaces, ingestion of cold foods or beverages, and infusion of cold substances (fluids, blood transfusions).
• Some individuals may require transfusions for severe anemia and/or hydration to prevent acute kidney injury |
| What is drug-induced hemolytic anemia? | • Immune (antibody-mediated) hemolysis, which can be drug dependent or drug-independent
• Oxidative damage and Methemoglobinemia
• Thrombotic microangiopathy (TMA)
In drug-dependent reactions, the drug binds to the RBC surface and becomes part of the antigen with which the antibody interacts
• Penicillin type, drug remains on RBC, and is required for antibody binding
• Immune complex type, the drug causes formation of immune complexes that bind to the RBCs and cause complement activation
• Passive absorption administration of antibody preparations introduces antibodies that can react with the recipients RBCs. eg IVIG
• In drug-independent, It can cause immune hemolysis several weeks to months after drug initiation. drug alters RBC membrane |
| What is paroxysmal nocturnal hemoglobinuria (PNH)? | • Clonal deficiency in glycosyl phophatidyl inositol (GPI-linked protiens on RBCs, neutrophils, and platelets)
GPI-linked proteins; which neutralize complements attached to RBC, neutrophils, and platelets
- DAF, decay-accelerating factor (CD55)
- MIRL, membrane-inhibitor reactive lysis (CD59)
- In the absence of this protein, RBCs are susceptible to complementmediated intravascular hemolysis |
| How is the presentation of PNH? | • Episodic (paroxysmal) hemolysis when complement is activated by mild acidosis:
- Respiratory acidosis during sleep (nocturnal)
- Lactic acidosis during exercise
• Can lead to IDA (iron deficiency anemia) from chronic blood loss
• Hepatic vein – Hepatic vein thrombosis (Budd-Chiari syndrome) in the setting of a hemolytic episode
• Inferior vena cava, portal and splenic veins: Thrombosis of other intra-abdominal vessels
• Dermal veins – discrete areas of erythema, swelling, and pain or as a syndrome resembling purpura fulminans
• Hemolysis: related to anemia/hemolysis such as smooth muscle dystonia, pulmonary hypertension, and renal insufficiency.
• Thrombosis: is the leading cause of death in PNH. It is relatively rare as a presenting symptom but eventually occurs in up to 40 percent of patients, if not treated.
• Pancytopenia: could overlap with bone marrow disorders; eg.aplastic anemia (AA) or occasionally MDS. Other factors include iron deficiency and hypersplenism |
| What are labs of PNH? | • Laboratory:
- hemolytic anemia with Coombs-negative
- loss of glycosylphosphatidylinositol (GPI)-anchored proteins.
- findings of organ damage from hemolysis and/or thrombosis.
• Bone marrow examination; if significant pancytopenia
• imaging for thromboses: in patients with intractable headache or severe abdominal pain. |
| How is dx of PNH? | - Flow cytometry- to look for CD59 (MIRL) and CD55 (DAF), absence or reduced expression of both CD59 and CD55 on RBCs is diagnostic.
- FLuorescent AERolysin (FLAER) a reagent derived from the bacterial toxin aerolysin, which binds directly to the GPI anchor
- PNH leukocytes have a low leukocyte alkaline phosphatase (LAP) score, which is similar to that of CML |
| What is micro/macroangiopathic hemolytic anemia? | Mechanical damage to RBC (due to stenotic/mechanical heart valve [waring blender effect] or malignant HTA)
Diseased endothelium (microthrombus formation, DIC, TTP [thrombotic thrombocytopenia purpura], and HUS. |
| What is thrombocytopenia purpura? | inhibition of vWF-cleaving protease (ADAMTS-13) idiopathic/autoimmune form, lack of enzyme activity prevents breakdown of vWF.
Excess circulation multimers of vWF promote adhesion of plt to endothelium, causes formation of microthrombi, leading to thrombocytopenia.
secondary/acquired (cancer, pregnancy, bone marrow transplant, immunosuppressants, HIV-1 we get no ADAMTS-13 suppression)
Inherited (Upshaw-Schulman syndrome)
Classic pentad (fever, thrombocytopenia, microangiopathic hemolytic anemia, renal failure, altered mentation)
fatal if not treated, treatment is plasma exchange (remove offending Abs and replaces ADAMTS-13) may use corticosteroids |
| What is HUS? | hemolytic uremic syndrome, caused by sepsis (mainly E.coli O157:H7, bacterial toxins cause endothelial damage, leading to formation of plt microthrombi and thrombocytopenia
Mostly in children, similar to TTP but more renal involvement/failure. Tx supportive dialysis until renal function returns (most recover w/in few weeks, some develop chronic renal failure) |
| What is DIC? | • Sepsis, especially E.coli and Neisseria meningitis
• Malignancy- any cancer especially APL (promyrlocytic leukemia) M3
• Obstetrical complications (eg eclampsia)
• Trauma- especially crush injury and burns
• Snake bites
• Activation of coagulation system
• Leading to extensive thrombus formation in the microvaculature resulting in:
• Obstruction of flow → tissue hypoxia
• Consumption of clotting factors and plt → risk of bleeding
• Activation of the fibrinolytic system → production of FDP/D-dimer |
| How is dx and tx of DIC? | Diagnosis is based on clinical history +
• ↑ PT/INR and PTT,
• Thrombocytopenia (↓plt)
• Fibrinogen N ↓
• ↑ D-dimer
• Microangiopathic hemolytic anemia (schistocytes)
• Signs of bleeding, petechiae, purpura, mucosal bleeding, etc.
• Treatment is supportive, Rx underlying disease (may use FFP, plt, or cryoprecipitate transfusion)
• Poor prognosis |
