BCSH haemoglobinopathy diagnosis guidelines (cid:27) www.bcshguidelines.com/pdf/bjh809.pdf 02-red cell disorders.qxd 10.12.2003 04.11 PM Page 93 Red cell disorders Hereditary persistence of fetal hemoglobin 93 Heterogeneous groups of disorders caused by deletions or cross-overs involving b and g chai n production, or non-deletional forms due to point mutations upstream of the g globin gene, with high levels of HbF produc- tion in adult life. There is 5 d and b chain production wi th enhanced g chain production. Globin chain imbalance is much less marked than in b thalas saemia, resulting in milder disorder. There are few clinical effects. May be pancellular (very high levels of HbF hemoglobin synthesis with uniform distribution in RBCs) or heterocellular (increased numbers of F cells). Mechanism Like db thalassaemia, HPFH frequently arises from deletions of DNA, which remove or inactivate the b globin gene (note: heterocellular HPFH may be result of mutations outsi de the b globin gene). Heterozygous HPFH Anemia may be mild or absent. Hematological indices are normal. There is balanced a/non-a globin chain synthesis. HbF level 25%. 02-red cell disorders.qxd 10.12.2003 04.11 PM Page 94 Hb patterns in hemoglobin disorders % Hemoglobin A F A2 S Other Normal 97 <1 2 \200\2233 b thalassaemia trait 80 \200\22395 b thalassaemia intermedia 30 \200\22350 b thalassaemia m ajor 0 \200\22320 1 \200\2235 50 \200\22370 80 \200\223100 3 \200\2237 0 \200\2235 0 \200\22313 94 HPFH (Black heterozygote) 60 \200\22385 HPFH (Black homozygote) 15 \200\22335 100 1 \200\2233 a thalassaemia trait HbH disease 85 \200\22395 60 \200\22395 Bart \200\231s 0 \200\22310% at birth H 5 \200\22330% Bart \200\231s 20 \200\22330% at birt h Bart \200\231s 80 \200\22390% HbBart \200\231s hydrops HbE trait HbE disease HbE/b thalassaemia HbE/a thalassaemia 60 \200\22365 0 0 13 1 \200\2232 5 \200\22310 30 \200\22340 2 \200\2233 5 \200\223 E 30 \200\22335 E 95 E 60 \200\22370 E 80 HbD trait HbD disease HbD/b thalassaemia 50 \200\22365 1-5 0-7 1-5 1-3 1-7 1 \200\2233 D 45 \200\22350 D 90 \200\22395 D 80 \200\22390 HbC trait HbC disease 60 \200\22370 C 30 \200\22340 C 95 slight 4 Sickle trait Sickle cell anemia Sickle/b+ thalassaemia Sickle/bo thalassaemia Sickle/D Sick le/C 55 \200\22370 0 5 \200\22330 0 0 0 1 7 5 \200\22315 5 \200\22330 1 \200\2235 1 3 3 \200\223 4 \200\2238 30 \200\22345 90 60 \200\22385 70 \200\22390 50 50 \200\22365 D 50% C 50% HbLepore trait 80 \200\22390 HbLepore disease HbLepore/b thalassaemia 1 \200\2233 0 2 \200\2232.5 70 \200\22390 70 \200\22390 Lepore 9 \200\22311% Lepore 8 \200\22330% Lepore 5 \200\22315% 0 2.5 02-red cell disorders.qxd 10.12.2003 04.11 PM Page 95 Red cell disorders 95 02-red cell disorders.qxd 10.12.2003 04.11 PM Page 96 Non-immune haemolysis 4 major groups 2 Infections. 2 Vascular (mechanical damage). 2 Chemical damage. 2 Physical damage. 96 Infection Malaria \200\224especially falciparum. Causes anemia through marrow suppression, hypersple nism and RBC sequestration. In addition there is haemolysis due to destruction of parasitis ed RBCs by RES and intravascular haemolysis when sporozoites released from infected RBCs. B lackwater fever refers to severe acute intravascular haemolysis with haemoglobinaemia, 5 Hb , haemoglobinuria and ARF. Babesiosis \200\224Babesia (RBC protozoan). Rapid onset of vomiting, diarrhea, rigors, jau ndice, 4T . Haemoglobinaemia, haemoglobinuria, ARF and death. Clostridium perfringens \200\224septicaemia and acute intravascular haemolysis. Viral \200\224especially viral haemorrhagic fevers e.g. dengue, yellow fever. Mechanical Cardiac \200\224turbulence and shear stress following mechanical valve replacement. Genera l feature of haemolysis: 4 reticulocytes, LDH, plasma Hb, with 5 haptoglobins platelets. Urinary haemosiderin +ve. MAHA \200\224see p112. HUS/TTP \200\224see p530. March haemoglobinuria \200\224with severe strenuous exercise e.g. running. Destruction of RBCs in soles of feet. Worse with hard soles and uneven hard ground. Mild anemia. No specif ic features on movie. May be associated GIT bleeding and 5 ferritin (lost in sweat). Chemical & physical Oxidative haemolysis \200\224chronic Heinz body intravascular haemolysis with dapsone or s alazopyrine in G6PD deficient people or unstable Hb (and normals if dose high enough). Movi e: bite cells (RBC). Heinz bodies not prominent if intact spleen. Haemolysis well compensat ed. MetHb \200\224see p110. Lead poisoning \200\224moderate 5 RBC lifespan. Anemia mainly due to block in haem synthesis although lead also inhibits 5 nucleotidase (NT). Basophilic st ippling on movie. Ring sideroblasts in BM. 02-red cell disorders.qxd 10.12.2003 04.11 PM Page 97 Red cell disorders O2 \200\224haemolysis in patients treated with hyperbaric O2. Insect bites \200\224e . g . spider, bee-sting (not common with snake bites). Heat \200 \224e . g . burns7severe haemolysis due to direct RBC damage. 97 Liver disease \200\224reduced RBC lifespan in acute hepatitis, cirrhosis, Zieve \200\231s syndrome is an uncommon form of haemolysis \200\224intravascular associated with acute abd ominal pain ((cid:9) p54). Wilson \200\231s disease \200\224autosomally inherited disorder of copper metabolism, with hepatolenticular, hepatocerebral degeneration. PNH \200\224see p124. Hereditary acanthocytosis \200\224a-b-lipoproteinaemia. Rare, inherited. Associated with r etinitis pigmentosa, steatorrhoea, ataxia and mental retardation. 02-red cell disorders.qxd 10.12.2003 04.11 PM Page 98 Hereditary spherocytosis Most common inherited RBC membrane defect characterized by variable degrees of haemolysis, spherocytic RBCs with 4 osmotic fragility. Pathophysiology Abnormal RBC cytoskeleton: partial deficiency of spectrin, ankyrin, band 3 or protein 4.2 (leads to 5 binding to band 4.1 protein and ankyrin). Loss of lipid from RBC membrane7spherical (cf. biconcave) RBCs with reduced surface area7get trapped in splenic c ords and have reduced lifespan. RBCs use more energy than normal in attempt to maintain cel l shape. RBC membrane has 4 Na+ permeability (loses intracellular Na+) and energy required to restore Na+ balance. Red cells are less deformable than normal. 98 Epidemiology In Northern Europeans 1:5000 people are affected. In most cases inheri- tance is autosomal dominant although autosomal recessive inheritance has been reported. Clinical features Presents at any age. Highly variable from asymptomatic to severely anemic , but usually there are few symptoms. Well-compensated haemol- ysis; other features of haem olytic anemia may be present e.g. splenomegaly, gallstones, mild jaundice. Occasional aplas tic crises occur, e.g. with parvovirus B19 infection. Diagnosis 2 Positive family history of HS in many cases. 2 Blood movie shows 44 spherocytic RBCs. 2 Anemia, 4 reticulocytes, 4 LDH, unconjugated bilirubin, urinary urobilinogen with 5 haptoglobins. DAT \200\223ve. Osmotic fragility test \200\224RBCs incubated in saline at various concentrations. Results in cell expansion and eventually rupture. Normal RBCs can withstand greater volume increas es than spherocytic RBCs. Positive result (i.e. confirms HS) when RBCs lyse in saline at ne ar to isotonic concentration, i.e. 0.6 \200\2230.8g/dL (whereas normal RBCs will simply sho w swelling with little lysis). Osmotic fragility more marked in patients who have not under gone splenectomy, and if the RBCs are incubated at 37 C for 24h before performing the test . Autohaemolysis test \200\224since spherocytic RBCs use more glucose than normal RBCs (to m aintain normal shape) red cells incubated in buffer or serum for 48h show lysis and release of Hb into solution, which can be measured. In HS RBCs release greater amounts of Hb cf. n ormal RBCs (3% vs. 1% in normal). Complications 2 Aplastic crisis (e.g. parvovirus B19 infection, but may be any virus); see temporary 55 reticulocytes, Hb and Hct. 2 Megaloblastic changes in folate deficiency. 2 4 h aemolysis during intercurrent illness e.g. infections. 2 Gallstones (in 50% patients; occur even in mild disease). 02-red cell disorders.qxd 10.12.2003 04.11 PM Page 99 Red cell disorders 2 Leg ulceration. 2 Extramedullary haemopoiesis. 2 Iron overload if multiply transfused. 99 Exclude Other causes of haemolytic anemia e.g. immune-mediated, unstable Hbs and MAHA, whic h can give rise to spherocytic RBCs. Treatment Supportive treatment is usually all that is required, e.g. folic acid (5mg/d). In parvovirus crisis Hb drops significantly and blood transfusion may be required. Splenectom y is \200\230curative \200\231 but is reserved for patients who are severely anemic or who have symptomatic moderate anemia. Best avoided in patients <10 years old due to risk of 4 fatal infection post- splenectomy. (cid:2) Remember pre-splenectomy vaccines and post-splenectomy antibiotics ((cid:9) p582). 100 Patient Control 75 Normal range % RBC lysis 50 25 0 0 0.2 0.4 0.6 0.8 1.0 % Saline Osmotic fragility assay: note control red cells (red) lyse at lower % saline since they are able to take up more water than spherocytic red cells before lysis occurs. Blood movie in hereditary spherocytosis: note large numbers of dark spherical red cells. 02-red cell disorders.qxd 10.12.2003 04.11 PM Page 100 Hereditary elliptocytosis Heterogeneous group of disorders with elliptical RBCs. 3 major groups 2 Hereditary elliptocytosis. 2 Spherocytic HE. 2 South East Asian ovalocytos is. 100 Pathophysiology Mutations in a or b spectrin. There may be partial, complete deficiency, or structural abnormality of protein 4.1, or absence of glycophorin C. Epidemiology In Northern Europeans 1:2500 are affected. Inheritance is autosomal dominant. More common in areas where malaria is endemic. Clinical features Most are asymptomatic. Well-compensated haemolysis. A few patients have c hronic symptomatic anemia. Homozygote more severely affected. Diagnosis 2 May have positive family history. 2 Blood movie shows 44 elliptical or oval RBC s. 2 Anemia, 4 reticulocytes, 4 LDH, unconjugated bilirubin, urinary urobilinogen with 5 haptoglobins. DAT is \200\223ve. 2 Osmotic fragility usually normal (unless spherocytic HE). 2 Transient increase in haemoly sis if intercurrent infection. Complications Usual complications of haemolytic anemia e.g. gallstones, folate defi- ciency , etc. Treatment Supportive care: folic acid (5mg/d). Most patients require no treatment. In more severe cases consider splenectomy. Remember pre-splenectomy vaccines and post-splenectomy a ntibiotics ((cid:9) p582). Spherocytic HE Elliptical and spherical \200\230sphero-ovalocytes \200\231 in peripheral b lood. Haemolysis and 4 osmotic fragility distinguish it from common hereditary elliptocy- t osis. Molecular basis is unknown. Southeast Asian ovalocytosis Caused by abnormal band 3 protein. RBCs are oval with 1 \200 \2232 transverse ridges. Cells have 4 rigidity and 5 osmotic fragility. RBCs are more resis - tant to malaria than normal RBCs. 02-red cell disorders.qxd 10.12.2003 04.11 PM Page 101 Red cell disorders 101 02-red cell disorders.qxd 10.12.2003 04.11 PM Page 102 Glucose-6-phosphate dehydrogenase de \201ciency G6PD is involved in pentose phosphate shun t 7generates NADP, NADPH and glutathione (for maintenance of Hb and RBC membrane integrity, and reverse oxidant damage to RBC membrane and RBC compo- nents). G6PD deficiency is X-lin ked and clinically important cause of oxidant haemolysis. Affects 9 predominantly; 3 carrie rs have 50% normal G6PD activity. Occurs in West Africa, Southern Europe, Middle East and S outh East Asia. 102 Features: 2 Haemolysis after exposure to oxidants or infection. 2 Chronic non-spherocytic h aemolytic anemia. 2 Acute episodes of haemolysis with fava beans (termed favism). 2 Methaem oglobinaemia. 2 Neonatal jaundice. Mechanism Oxidants7denatured Hb7methaemoglobin7Heinz bod ies7RBC less deformable7destroyed by spleen. 2 main forms of the enzyme: normal enzyme is G6PD-B, most prevalent form worldwide; 20% of Africans are type A. A and B differ by one amino acid. Mutant enzyme with normal activity = G6PD A(+), find only in Black individuals. G6PD A( \200\223) is main defect in African ori gin; 5 stability of enzyme in vivo; 5 \200\22315% normal activity. 400+ variants but only 2 are rele- vant clinically: type A( \200\223) = Africans (10% enzyme activity) and Mediterr anean (with 1 \200\2233% activity). Drug-induced haemolysis in G6PD deficiency 2 Begins 1 \200\2233d after ingestion of drug. 2 Anemia most severe 7 \200\22310d after ingestion. 2 Associated with low back and abdominal pain. 2 Urine becomes dark (black sometimes). 2 Red cells develop Heinz body inclusions (c leared later by spleen). 2 Haemolysis is typically self-limiting. 2 Implicated drugs shown in table (next page). 2 But heterogeneous; variable sensitivity to drugs. 2 Risk and severi ty are dose related. Haemolysis due to infection and fever 2 1 \200\2232d after onset of fever. 2 Mild anemia de velops. 2 Commonly seen in pneumonic illnesses. Favism 2 Hours/days after ingestion of fava beans (broad beans). 2 Beans contain oxidants v icine and convicine7free radicals7oxidize glutathione. 2 Urine becomes red or very dark. 2 Shock may develop \200\224may be fatal. 02-red cell disorders.qxd 10.12.2003 04.11 PM Page 103 Red cell disorders Risk of haemolysis in G6PD deficient individuals 103 Definite risk Possible risk Antimalarial drugs Primaquine Pamaquine (not available in UK) Aspirin (1g/d acceptable in most cases) Chloroquine Probenecid Quinine & quinidine (accepta ble in acute malaria) Analgesic drugs Aspirin Phenacetin Others Dapsone Methylthioninium chloride (methylene blue) Nitrofurantoin 4-quinolones (e.g. ciprofloxacin, nalidixic acid) Sulphonamides (e.g. cotrimoxazole) Neonatal jaundice 2 May develop kernicterus (possible permanent brain damage). 2 Rare in A( \200\223) variants. 2 More common in Mediterranean and Chinese variants. Laboratory investigation 2 In steady state (i.e. no haemolysis) the RBCs appear normal. 2 H einz bodies in drug-induced haemolysis (methyl violet stain). 2 Spherocytes and RBC fragmen ts on blood movie if severe haemolysis. 2 4 reticulocytes. 2 4 unconjugated bilirubin, LDH and urinary urobilinogen. 2 5 haptoglobins. 2 DAT \200\223ve. Diagnosis Demonstrate enzyme deficiency. In suspected RBC enzymopathy, assay G6PD and PK fi rst, then look for unstable Hb. Diagnosis is difficult during haemolytic episode since reti culocytes have 44 levels of enzyme and may get erroneously normal result; wait until steady state ( 6 weeks after episode of haemolysis). Family studies are helpful. Management 2 Avoid oxidant drugs \200\224see BNF. 2 Transfuse in severe haemolysis or symp tomatic anemia. 2 IV fluids to maintain good urine output. 2 exchange transfusion in inf ants. 2 Splenectomy may be of value in severe recurrent haemolysis. 2 Folic acid supplement s (?proven value). 2 Avoid iron unless definite iron deficiency. 02-red cell disorders.qxd 10.12.2003 04.11 PM Page 104 Pyruvate kinase de \201ciency Congenital non-spherocytic haemolytic anemia, caused by deficiency of PK enzyme (involved i n glycolytic pathway), leading to unstable enzyme with reduction in ATP generation in RBCs. O2 curve is shifted to the right due to 4 2,3-DPG production. 104 Epidemiology Autosomal recessive. Affected persons are homozygous or double het- erozygotes . Clinical features Variable, with chronic haemolytic syndrome. May be apparent in neonate (i f severe) or may present in later life. Diagnosis 2 Variable anemia. 2 Reticulocytes 44. 2 DAT \200\223ve. 2 LDH 4. 2 Serum haptog lobin 5. 2 Definitive diagnosis requires assay of PK level. Complications Aplastic crisis may be seen in viral infection (e.g. parvovirus B19). Treatment Dependent on severity. General supportive measures include daily folic acid (5mg/ d). Transfusion may be required. Splenectomy may be of value if high transfusion requiremen ts. In aplastic crisis (e.g. viral infection) support measures should be used. Zanella, A. & Bianchi, P. (2000) Red cell pyruvate kinase deficiency: from genetics to clin ical mani- festations. Baillieres Best Pract Res Clin Haematol, 13, 57 \200\22381. 02-red cell disorders.qxd 10.12.2003 04.11 PM Page 105 Red cell disorders GLUCOSE ATP 105 Glucose 6-phosphate dehydrogenase ADP Glucose 6-phosphate Glucose 6-phosphogluconate NADP NADPH Hexose monophosphate shunt Fructose 6-phosphate ATP ADP GSSG G-SH Fructose 1,6-diphosphate Glyceraldehyde 3-phosphate Ribulose 5-phosphate NAD GLYCOLYSIS NADH 1,3-diphosphoglycerate Mutase ADP 2,3-diphosphoglycerate ATP 3-phosphoglycerate Phosphatase Luebering-Rappaport Shunt 2-phosphoglycerate Phosphoenolpyruvate ADP Pyruvate kinase ATP Pyruvate Glycolytic pathway showing key enzymes in red 02-red cell disorders.qxd 10.12.2003 04.11 PM Page 106 Other red cell enzymopathies Glycolytic pathway 2 Hexokinase deficiency. 2 Glucose phosphate isomerase deficiency. 2 Pho sphofructokinase deficiency. 2 Aldolase deficiency. 2 Triosephosphate isomerase deficiency. 2 Phosphoglycerate kinase deficiency. 106 Epidemiology Incidence <1 in 106. Inheritance is autosomal recessive (most double heterozyg ote) except for phosphoglycerate kinase deficiency (X-linked recessive). Clinical features Similar to PK deficiency although most are more severely affected for the degree of anemia (glycolytic block results in 5 2,3-DPG and left shift of O2 dissociation curve). PFK deficiency is associated with myopathy. TPI and PGK deficiencies are associated with progressive neurological deteri- oration. Diagnosis 2 See pyruvate kinase deficiency (p104). 2 Non-specific morphology with anisocyto sis, macrocytosis and polychromasia. 2 Definitive diagnosis requires assay of deficient enzyme (7reference lab). Complications 2 See pyruvate kinase deficiency (p104). Treatment Folic acid (5mg/d). Transfusion may be required (beware Fe overload if high trans fusion requirement). Role of splenectomy controversial. Natural history Similar to pyruvate kinase except TPI and PGK \200\223TPI present in childh ood and cause progressive paraparesis, most die <5 years old due to cardiac arrhythmias. PG K can cause exertional rhabdomyolysis and consequential renal failure. Those affected show progressive neurological deterioration. Nucleotide metabolism \200\224pyrimidine 5 nucleotidase deficiency Epidemiology Autosomal recessive. Note: lead poisoning causes acquired pyrimidine 5 nucleo tidase deficiency. Clinical features 2 Moderate anemia (Hb 10g/dL). 2 4 Reticulocytes. 2 4 bilirubin. 2 Splen omegaly. 02-red cell disorders.qxd 10.12.2003 04.11 PM Page 107 Red cell disorders Diagnosis 2 RBCs show prominent basophilic stippling. 2 Pyrimidine 5 nucleotidase assay. 107 Treatment Symptomatic, splenectomy is of limited value. 02-red cell disorders.qxd 10.12.2003 04.11 PM Page 108 Drug-induced haemolytic anemia Large number of drugs shown to cause haemolysis of RBCs. Mechanisms variable. May be immune or non-immune. 2 Some drugs interfere with lipid component of RBC membrane. 2 Oxidation an d denaturation of Hb: seen with e.g. sulphonamides, espe- cially in G6PD deficient subjects , but may occur in normal subjects if drugs given in large doses e.g. \200\223 Dapsone. \200\223 Sulfasalazine. 108 2 Hapten mechanism describes the interaction between certain drugs and the RBC membrane com ponents generating antigens that stimu- late antibody production. DAT +ve. \200\223 Penici llins. \200\223 Cephalosporins. \200\223 Tetracyclines. \200\223 Tolbutamide. 2 Autoantibody mediated haemolysis is associated with warm anti- body mediated AIHA. DAT +ve. \200\223 Cephalosporins. \200\223 Mefenamic acid. \200\223 Methyldopa. \200\223 Procainamide. \200\223 Ibuprofen. \200\223 Diclofenac. \200\223 IF N-a. 2 Innocent bystander mechanism occurs when drugs form immune complexes with antibody (IgM commonest) which then attach to RBC membrane. Complement fixat ion and RBC destruction occurs. \200\223 Quinine. \200\223 Quinidine. \200\223 Rifampici n. \200\223 Antihistamines. \200\223 Chlorpromazine. \200\223 Melphalan. \200\223 Tetra cycline. \200\223 Probenecid. \200\223 Cefotaxime. Laboratory features As for autoimmune haemolytic anemia, Hb 5, reticulocytes 4, etc. Differential diagnosis 2 Warm/cold autoimmune haemolytic anemia. 2 Congenital haemolytic di sorders, e.g. HS, G6PD deficiency, etc. Treatment 2 Discontinue offending drug. 2 Choose alternative if necessary. 2 If DAT +ve wit h methyldopa no need to stop unless haemolysis. 2 Corticosteroids generally unnecessary and of doubtful value. 2 Transfuse in severe or symptomatic cases only. 2 Outlook good with co mplete recovery usual. 02-red cell disorders.qxd 10.12.2003 04.11 PM Page 109 Red cell disorders 109 02-red cell disorders.qxd 10.12.2003 04.11 PM Page 110 Methaemoglobinaemia The normal O2 dissociation curve requires iron to be in the ferrous form (i.e. reduced, Fe2 +). Hb containing the ferric (oxidized, Fe3+) form is termed methaemoglobin (MetHb). MetHb binds O2 tightly leading to poor tissue oxygenation. May be congenital or acquired. 110 Methaemoglobinaemia Congenital HbM a or b globin mutation in vicinity of Fe Fe becomes stabilized in Fe3+ form Heterozygote ha s 25% HbM Due to deficiency of NADH-cytochrome b5 reductase. Autosomal recessive inheritanc e; symptoms mainly in homozygote Cyanosis from infancy. PaO2 is normal General health is go od MetHb reductase def. Clinical features Acquired Occurs when RBCs are exposed to oxidizing agents, producing HbM. Implicated agents include: phenacetin, local anesthetics (e.g. lignocaine), inorganic nitrates (NO2). Patients may ex perience severe tissue hypoxia. HbM binds O2 tightly and fails to release to tissues (cid:2)(cid:2) HbM \211 60% requires urgent medical attention. Diagnosis May be history of exposure to oxidant drugs or chemicals. Spectrophotometry or he moglobin electrophoresis will demonstrate HbM. Assays for MetHb reductase are available. Treatment In patients with congenital symptomatic HbM give ascorbate or methylth- ioninium chloride (methylene blue). In acquired disorder remove oxidant, if present, and administer methylthioninium chloride (methylene blue). (cid:2) If severely affected consider exchange blood transfusion. 02-red cell disorders.qxd 10.12.2003 04.11 PM Page 111 Red cell disorders 111 02-red cell disorders.qxd 10.12.2003 04.11 PM Page 112 Microangiopathic haemolytic anemia (MAHA) Definition Increased RBC destruction caused by mechanical red cell deformation. Caused by t rauma or vascular endothelial abnormalities. 112 Causes 2 TTP/HUS see p468, 530. 2 PET/HELLP (haemolysis, elevated liver enzymes and low pla telets). 2 Malignant tumor circulations. 2 Renal abnormalities e.g. acute glomerulonephriti s, transplant rejection, cyclosporin. 2 Vasculitides e.g. Wegener \200\231s, PAN, SLE. 2 DIC. 2 Prosthetic heart valves. 2 March haemoglobinuria. 2 A-V malformations. 2 Burns. Clinical 2 Varying degree of anemia \200\224most severe in DIC, TTP/HUS and HELLP. 2 Often associated with 5 platelets. 2 Blood movie shows marked RBC fragmentation, stomatocytes an d spherocytes. 2 Reticulocytosis often very marked. 2 Signs of underlying disease should be sought. Treatment 2 Diagnose and treat underlying disease. 2 Give folic acid and iron supplements i f deficient. Antman, K.H. et al. (1979) Microangiopathic hemolytic anemia and cancer: a review. Medicine (Baltimore), 58, 377 \200\223384. 02-red cell disorders.qxd 10.12.2003 04.11 PM Page 113 Red cell disorders 113 02-red cell disorders.qxd 10.12.2003 04.11 PM Page 114 Acanthocytosis Abnormal RBC shape (thorn-like surface protrusions) seen in a number of conditions, inherit ed or acquired, affecting RBC membrane lipid structure. RBCs develop normally in marrow but once in plasma adopt characteristic shape. RBCs lose membrane and become progressively les s elastic. 114 Inherited conditions resulting in significant acanthocytosis 2 A-b-lipoproteinaemia. 2 McLe od phenotype (lacking Kell antigen). 2 In(Lu) phenotype. 2 In association with abnormalitie s of band 3 protein. 2 Hereditary hypo- -lipoproteinaemia. Acquired conditions resulting in significant acanthocytosis 2 Severe liver disease. 2 Myelo dysplastic syndromes. 2 Neonatal vitamin E deficiency. Inherited conditions resulting in mild acanthocytosis 2 McLeod phenotype heterozygote. 2 Py ruvate kinase deficiency. Acquired conditions resulting in mild acanthocytosis 2 Post-splenectomy and hyposplenic sta tes. 2 Starvation including anorexia nervosa. 2 Hypothyroidism. 2 Panhypopituitarism. A-bb-lipoproteinaemia recessive. Congenital absence of b apolipoprotein. Autosomal Choleste rol:phospholipid ratio 4. RBC precursors normal. Usually obvious in early life with associa ted malabsorption of fat (including vita- mins A, D, E and K). Sphingomyelin accumulates. Hematological abnormalities 2 Mild haemolytic anemia. 2 50 \200\22390% circulating RBCs are acanthocytic. 2 Reticulocytes mildly 4. McLeod phenotype 2 5 expression of Kell antigen on RBC. 2 Mild (compensated) haemolytic ane mia. 2 10 \200\22385% acanthocytic RBCs in peripheral blood. 02-red cell disorders.qxd 10.12.2003 04.11 PM Page 115 Red cell disorders 115 02-red cell disorders.qxd 10.12.2003 04.11 PM Page 116 Autoimmune haemolytic anemia RBCs react with autoantibody complement7premature destructi on of RBCs by reticuloendothelial system. Mechanism IgG, recognized by Fc receptors on RES RBCs opsonised by macrophages7phagocytosis . incomplete remaining portion of RBC continues to circulate as spherocyte (note: phagocyto sis usually complete if complement involved). 116 If phagocytosis Seen in 2 Haemolytic blood transfusion reactions. 2 Autoimmune haemolytic anemia. 2 Drug-in duced haemolysis (some). Warm antibody induced Idiopathic 2 to lymphoproliferative disease e.g. CLL, NHL 2 to other autoimmune disease s e.g. SLE Cold antibody induced Idiopathic Cold haemagglutinin disease (CHAD) 2 to Mycoplasma infection Infectious mononu cleosis Lymphoma Paroxysmal cold haemoglobinuria Idiopathic 2 to viral infection Congenital or tertiary syphilis Warm antibody induced haemolysis Extravascular RBC destruction by RES mediated by warm-reac ting anti- body. Most cases are idiopathic with no underlying pathology, but may be 2 to lymphoid malignancies e.g. CLL, or autoimmune disease such as SLE. Epidemiology Affects predominantly individuals >50 years of age. Clinical features 2 Highly variable symptoms, asymptomatic or severely anemic. 2 Chronic co mpensated haemolysis. 2 Mild jaundice common. 2 Splenomegaly usual. Diagnosis 2 Anemia. 2 Spherocytes on peripheral blood movie. 2 Reticulocytes are 44. 2 Neut rophilia common. 2 RBC coated with IgG, complement or both (detect using DAT). 2 Autoantibo dy \200\224often pan-reacting but specificity in 10 \200\22315% (Rh, mainly anti-e, anti-D or anti-c). 02-red cell disorders.qxd 10.12.2003 04.11 PM Page 117 Red cell disorders 2 LDH 4. 2 Serum haptoglobin 5. 2 Exclude underlying lymphoma (BM, blood and marrow cell ma rkers). 2 Autoimmune profile \200\224to exclude SLE or other connective tissue dis- 117 order. Treatment Prednisolone 1mg/kg/d PO tailing off after response noted (usually 1 \200\2232 we eks). If no response consider immunosuppression e.g. azathioprine (suitable for elderly but not younger patients \200\224risk of 2 leukemia) or cyclophosphamide. Splenectomy shoul d be considered in selected cases. IVIg (0.4g/kg/d for 5d) useful in refractory cases, or w here rapid response required. Rituximab (anti-CD20) is emerging as a useful agent for a ran ge of refractory autoimmune disorders, including AIHA. Regular folic acid (5mg/d) is advise d. Gehrs, B.C. & Friedberg, R.C. (2002) Autoimmune hemolytic anemia. Am J Hematol, 69, 258 \200\223271. 02-red cell disorders.qxd 10.12.2003 04.11 PM Page 118 Cold haemagglutinin disease (CHAD) Describes syndrome associated with acrocyanosis in cold weather due to RBC agglutinates in blood vessels of skin. Caused by RBC antibody that reacts most strongly at temperatures <32 C. Complement is acti- vated 7RBC lysis7haemoglobinaemia and haemoglobinuria. May be idio pathic (1 ) or 2 to infection with Mycoplasma or EBV (infectious mononucleosis). 118 Clinical features 2 Elderly. 2 Acrocyanosis (blue discoloration of extremities e.g. fingers , toes) in cold conditions. 2 Chronic compensated haemolysis. 2 Splenomegaly usual. Diagnosis 2 Anemia. 2 Reticulocytes are 44. 2 Neutrophilia common. 2 Positive DAT \200\224 C3 only. 2 Autoantibodies \200\224IgG or IgM \200\223 Monoclonal in NHL. \200\223 Polyclonal in infection-related CHAD. 2 IgM antibodies react best at 4 C (thermal amplitude 4 \200\22332 C). 2 Specificity \200\223 Anti-I (Mycoplasma). \200\223 Anti-i (infectious mononucleosis) \200\224causes l ittle haemolysis in adults since RBCs have little anti-i (cf. newborn i >> I). 2 LDH 4. 2 Serum haptoglobin 5. 2 Exclude underlying lymphoma (BM, blood and marrow cell ma rkers). 2 Autoimmune profile to exclude SLE or other connective tissue dis- order. Treatment 2 Keep warm. 2 Corticosteroids generally of little value. 2 Chlorambucil or cyclo phosphamide (greatest value when there is underlying B-cell lymphoma, occasionally helpful in 1 CHAD). 2 Plasma exchange may help in some cases. 2 If blood transfusion required use in-line blood warmer. 2 Splenectomy occasionally useful (note: liver is main site of RBC seques- tration of C3b-coated RBCs). 2 Infectious CHAD generally self-limiting. Natural history Prolonged survival, spontaneous remissions not unusual, with periodic relap ses. 02-red cell disorders.qxd 10.12.2003 04.11 PM Page 119 Red cell disorders 119 02-red cell disorders.qxd 10.12.2003 04.11 PM Page 120 Leucoerythroblastic anemia Definition A form of anemia characterized by the presence of immature white and red blood c ells in the peripheral blood. Mature white cells and platelets are also often reduced. 120 Causes Marrow infiltration by 2 2 malignancy: commonly breast, lung, prostate, thyroid, k idney, colon. 2 Myelofibrosis (a primary myeloproliferative disorder, see p256). 2 Other he matological malignancy e.g. myeloma and Hodgkin \200\231s disease. 2 Rarely, severe haemoly tic or megaloblastic anemia. Marrow stimulation by 2 Infection, inflammation, hypoxia, trauma (common in ITU patients). 2 Massive blood loss. When due to marrow infiltration, there is often associated neutropenia thrombocytopenia. Marrow stimulative causes often have neutrophilia and thrombocytosis. Investigations 2 FBC and blood movie. Typical movie appearances are of increased poly- chromasia due to reticulocytosis, nucleated RBCs, poikilocytosis (tear drop forms common in infiltrative causes), myelocytes and band forms, occasionally even promyelocytes and blast cells. 2 Clotting screen \200\224where cause is 2 malignancy or infective, DIC may occur. Bone marrow is usually diagnostic 2 Hypercellular BM with normal cell maturation, typical o f marrow stim- ulation causes. 2 Infiltration with neoplastic cells of a 2 malignancy may be identified as abnormal clum ps with characteristic morphology \200\224immunohistochem- istry may identify the primary source e.g. PSA for prostate. 2 Increase in reticulin fibers running in parallel bundles identifies fibrotic infiltrative cause \200\224usually myelofibrosis, but may occur with other hematological malignancy. Treatment 2 Diagnose and treat underlying cause if possible. 2 Supportive transfusions as r equired, management of bone marrow failure (see p562). Oster, W. et al. (1990) Erythropoietin for the treatment of anemia of malignancy associated with neoplastic bone marrow infiltration. J Clin Oncol, 8, 956 \200\223962. 02-red cell disorders.qxd 10.12.2003 04.11 PM Page 121 Red cell disorders 121 02-red cell disorders.qxd 10.12.2003 04.11 PM Page 122 Aplastic anemia Definition A gross reduction or absence of haemopoietic precursors in all 3 cell lin- eages in bone marrow resulting in pancytopenia in peripheral blood. Although this encompasses al l situations in which there is myelosuppres- sion, the term is generally used to describe t hose in which spontaneous marrow recovery is unusual. 122 Incidence Rare 5 cases per million population annually. Wide age range, slight increase ar ound age 25 years and >65 years. 10 more common in Orientals. Causes Divided into categories where aplasia is regarded as: 2 Inevitable \200\223 TBI dose of >1.5Gy (note: >8Gy always fatal in absence of graft rescue). \200\223 Chemotherapy e.g. high dose busulfan. 2 Hereditary \200\223 Fanconi syndrome \200\224stem cell repair defect resulting in abnormali- ties of skin, facies, musculo-skeletal system and urogenital systems. \200\223 BM failure often delayed until adulthood. 2 Idiosyncratic \200\223 Chronic benzene exposure. \200\223 Drug-induced, but not dose related \200\224ma inly gold, chloramphenicol, phenylbutazone, NSAIDs, carbamazepine, phenytoin, mesalazine. \200\223 Genetic predisposition demonstrated for chloramphenicol. 2 Post-viral \200\223 Parvoviral infections \200\224classically red cell aplasia but may be all ele- me nts. Devastating in conjunction with chronic haemolytic anemia e.g. aplastic sickle crisis. \200\223 Hepatitis viruses A, B and C, CMV and EBV. 2 Idiopathic \200\223 Constitute the majority of cases. Classification 2 According to severity most clinically useful. 2 Defines highest risk group s. Classification of severity in aplastic anemia neutrophils <0.5 109/L <20 109/L platelets reticulocytes <1% neutrophils <0.2 109/ L, and infection present Severe 2 of the following: Very severe 02-red cell disorders.qxd 10.12.2003 04.11 PM Page 123 Red cell disorders Clinical features Reflects the pancytopenia. Bleeding from mucosal sites common, with purpu ra, ecchymoses. Infections, particularly upper and lower respiratory tracts, skin, mouth, p eri-anal. Bacterial and fungal infections common. Anemic symptoms usually less severe due t o chronic onset. 123 Diagnosis and investigation 2 FBC and blood movie show pancytopenia, MCV may be 4, movie mo r- phology unremarkable. 2 Reticulocytes usually absent. 2 BM aspirate and trephine show gross reduction in all haemopoietic tissue replaced by fat spaces \200\224important to exclude hypocellular MDS or leukemia \200\224the main differential diagnoses. 2 Flow cytometry using anti-CD55 and anti-CD59 will show lack of both membrane proteins. Ham \200\231s acid lysis test is now largely obsolete. 2 Specialized cyt ogenetics on blood to exclude Fanconi syndrome (see p456). Complications 2 Progression to more severe disease. 2 Evolution to PNH \200\224occurs in 7 %. 2 Transformation to acute leukemia occurs in 5 \200\22310%. Treatment 2 Mild cases need careful observation only. More severe will need sup- portive treatment with red cell and platelet transfusions and antibiotics as needed. Blood products should be CMV \200\223ve, and preferably leu- codepleted to reduce risk of sensit isation. 2 Specific treatment options are between allogeneic transplant and immunosuppression. 2 Sibling allogeneic transplant treatment of choice for those <50 with sibling donor. Shoul d go straight to transplant avoiding immunosup- pression and blood products if possible. 2 Matched unrelated donor transplant should be considered in <25 age group. 2 Immunosuppressive options include anti-lymphocyte globulin (ALG) cyclosporin. Response to ALG may take 3 months. Refractory or relapsing patients may respond to a second course of ALG from another animal. 2 Cyclosporin post-ALG looks promising. 2 Androgens or danazol may be useful in some cases. Abkowitz, J.L. (2001) Aplastic anemia: which treatment? Ann Intern Med, 135, 524 \200\22352 6; Young, N.S. & Barrett, A.J. (1995) The treatment of severe acquired aplastic anemia. Blo od, 85, 3367 \200\2233377. 02-red cell disorders.qxd 10.12.2003 04.11 PM Page 124 Paroxysmal nocturnal haemoglobinuria Definition Acquired clonal abnormality of cell membranes rendering them more sen- sitive to complement-mediated lysis, most noticeable in RBCs. Cells lack phosphatidylinositol glycop roteins (PIG) transmembrane anchors. 124 Incidence Rare. Aplastic anemia is closely related. Clinical features 2 Chronic intravascular haemolytic anemia particularly overnight (?due to lower blood pH). Infections trigger acceleration of haemolysis. 2 WBC and platelet production also often 5. 2 Chronic haemolysis may induce nephropathy. 2 Haemoglobinuria usually results in iron deficiency. 2 44 tendency to venous thrombosis part icularly at atypical sites e.g. hepatic vein (Budd \200\223Chiari syndrome), sagittal sinus thrombosis. 2 Fatigue, dysphagia and impotence occasionally seen. Diagnosis and treatment 2 FBC, blood movie \200\224polychromasia and reticulocytosis (cf. AA). 2 BM aspirate and trephine biopsy \200\224usually hypoplastic with increased fat spac e but with erythropoietic nests or islands distinct from AA. 2 Ham \200\231s test (acidifie d serum lysis) is invariably +ve though seldom used now. 2 Cellular immunophenotype shows altered PIG proteins, CD55 and CD59. 2 Urinary haemosiderin +ve. Complications 2 May progress to more severe aplasia. 2 Transforms to acute leukemia in 5%. 2 Serious thromboses in up to 20%. Treatment: 2 Chronic disease \200\224supportive care may be satisfactory in mild cases. 2 Iron replacement usually required. 2 Trial of steroid/androgens/danazol may 5 symptoms and transfusion need. 2 ALG/cyclosporin may be indicated for more severe cases as for aplastic anemia. 2 Acute major thromboses should be treated aggressively with urgent thrombolysis and 10 day s heparin. Long-term warfarin mandatory. Consider warfarin prophylaxis after any one clotti ng episode. 2 Severe cases <50 years should be considered for sibling allogeneic transplant if they have a donor \200\224consider MUD in <25 age group if no sibling donor. 02-red cell disorders.qxd 10.12.2003 04.11 PM Page 125 Red cell disorders Prognosis: Median survival from diagnosis is 9 years. Major cause of mortality is thrombosi s and marrow failure. Molecular genetic basis now established \200\224could be a candidate disease for gene transplantation. 125 Hillmen, P. et al. (1995) Natural history of paroxysmal nocturnal hemoglobinuria. N Engl J Med, 333, 1253 \200\2231258; Rosse, W.F. (1997) Paroxysmal nocturnal hemoglobinuria as a mo lecular disease. Medicine (Baltimore), 76, 63 \200\22393. 02-red cell disorders.qxd 10.12.2003 04.11 PM Page 126 Pure red cell aplasia Definition A severe anemia characterized by reticulocytes <1% in PB, <0.5% mature erythrobl asts in BM but with normal WBC and platelets. 126 Incidence Rare. Classification of red cell aplasia Congenital Diamond \200\223Blackfan anemia (DBA), see p452 Acquired Childhood: Transient erythroblastopenia of childhood (TEC) Adults: Primary: autoimmune or idiopathic Secondary chronic: thymoma, hematological malignancies es pecially CLL, pernicious anemia, some solid tumors, SLE, RA, malnutrition with riboflavin d eficiency Secondary transient: infections especially Parvovirus B19, CMV, HIV, many drugs R ecent interest following red cell aplasia in renal patients treated with subcutaneous Epo Clinical features 2 Lethargy usually only symptom of the anemia since slow onset. 2 No abno rmal physical signs except of any underlying disease.