Rouleaux Chronic inflammation, paraproteinaemia, myeloma 44 Reticulocytes Bleeding, haemolysis, marrow infiltration, severe hypoxia, response to haematinic therapy Heinz bodies Not seen in normals (removed by spleen), small numbers seen post-splenectomy, oxidant drugs , G6PD deficiency, sulphonamides, unstable Hb (Hb Zurich, K ln) Howell-Jolly bodies Made of DNA, generally removed by the spleen, dyserythropoietic states e.g. B12 deficiency, MDS, post-splenectomy, hyposplenism H bodies HbH inclusions, denatured HbH (b4 tetramer), stain with methylene blue, seen in HbH disease ( \200\223 \200\223/ \200\223 a), less prominent in a thalassaemia trait, not present in normals Hyposplenic blood movie Howell \200\223Jolly bodies, target cells, occasional nucleated RBC s, lymphocytosis, macrocytosis, acanthocytes 02-red cell disorders.qxd 10.12.2003 04.10 PM Page 45 Red cell disorders 45 02-red cell disorders.qxd 10.12.2003 04.10 PM Page 46 Anemia in renal disease Anemia is consistently found in the presence of chronic renal failure. Severity generally r elates to the degree of renal impairment. The domi- nant mechanism is inadequate production of erythropoietin. Other con- tributory factors include (i) suppressive effects of uraemia and (ii) 5 in RBC survival. Uraemia impairs platelet function leading to blood loss and Fe deficiency. Small amounts of blood are inevitably left in the tubing fol- lowing dialysis so that blood loss and Fe deficiency are further contribu- in dialysis and tory supplementa tion is required to avoid deficiency. Aluminum toxicity (from trace amounts in dialysis flu ids) and osteitis fibrosa from hyperparathy- roidism are rare contributory factors. 46 factors in dialysis patients. Folate is lost Laboratory features 2 Hb typically 5.0 \200\22310.0g/dL. 2 MCV 6. 2 Blood movie \200\224 m ostly normochromic RBCs; schistocytes and acantho- cytes present. No specific abnormalities in WBC or platelets. 2 Microangiopathic haemolytic changes present in vasculitic collagen dis- orders with renal failure and classically in HUS and TTP. Management 2 Short term treatment with RBC transfusion, based on symptoms (not Hb). 2 Corre ction of Fe and folic acid deficiencies. 2 Erythropoietin (Epo) will correct anemia in most patients. Start at 50 \200\223100units/kg SC 3/week. Give IV iron at same time. Response apparent <10 weeks; reduced doses required as mainte- nance. Renal Association guidelines have been produced for applica- tion and monitoring of Epo therapy. Although expensive it improves qu ality of life and avoids transfusion dependency and iron overload. Side effects of Epo 2 4 BP. 2 Pure red cell aplasia. 2 Thrombotic tendency. Blood movie: chronic renal failure with burr (irregular shaped) cells. (cid:27) www.nephronline.org/standards3/ 02-red cell disorders.qxd 10.12.2003 04.10 PM Page 47 Red cell disorders 47 Eschbach, J.W. et al. (1987) Correction of the anemia of end-stage renal disease with recom binant human erythropoietin. Results of a combined phase I and II clinical trial. N Engl J Med, 316, 73 \200\22378; Levin, N., et al. (1997) National Kidney Foundation: Dialysis Outc ome Quality Initiative develop- ment of methodology for clinical practice guidelines. Neph rol Dial Transplant, 12, 2060 \200\2232063. 02-red cell disorders.qxd 10.12.2003 04.10 PM Page 48 Anemia in endocrine disease Anemia and other hematological effects occur in various endocrine dis- orders. The abnormal ities will usually correct as the endocrine abnor- mality is corrected. Pituitary disorders 48 Deficiency/hypopituitarism is associated with normochromic, normo- cytic anemia; associated leucopenia may also occur. Abnormalities correct as normal function is restored, by replac ement therapy. Thyroid disorders Hypothyroidism may produce a mild degree of anemia; MCV usually 4 but may be normal. Corrects on restoration of normal thyroid function. Menorrhagia occurs in hypot hyroidism and can result in associated Fe deficiency. B12 levels should be checked because of the association with other autoimmune disorders (e.g. pernicious anemia). Thyrotoxicosis may be associated with mild degrees of normochromic anemia in 20% of cases w hich corrects as function is normalized. Erythroid activity is increased but a disproportio nate increase in plasma volume means either no change in Hb concentration or mild anemia. H aematinic deficiencies occur and should be excluded. Adrenal disorders Hypoadrenalism results in normochromic, normocytic anemia; the plasma volume is 5 which mas ks the true degree of associated anemia. The abnormalities are corrected by replacement min eralocorticoids. Hyperadrenalism (Cushing \200\231s) results in erythrocytosis with a typical net increase i n Hb (by 1 \200\2232g/dL). Occurs whether Cushing \200\231s is primary or iatrogenic. Mecha nism is unclear. Parathyroid disorders \200\224hyperparathyroidism may be associated with anemia from impai rment of erythropoietin production, or in some cases from secondary marrow sclerosis. Sex hormones \200\224androgens are occasionally used to stimulate red cell production in a plastic anemia. The influence of androgens explains the higher Hb in adult 9 cf. 3. Diabete s mellitus when poorly controlled may be associated with anemia; however, the majority of h ematological abnormalities in diabetes mellitus result from secondary disease related compl ications e.g. renal failure. stimulate erythropoiesis and 02-red cell disorders.qxd 10.12.2003 04.10 PM Page 49 Red cell disorders 49 02-red cell disorders.qxd 10.12.2003 04.10 PM Page 50 Anemia in joint disease Rheumatoid arthritis, psoriatic arthropathy and osteoarthritis may be complicated by anemia . Various factors contribute to anemia, com- monly more than one is present, especially in rheumatoid arthritis. Some of the mechanisms that give rise to anemia in rheumatoid also ap ply in other connective tissue disease, e.g. SLE, polyarteritis nodosa, etc. 50 Anemia of chronic disorders (ACD) ACD is a cytokine-driven suppression of red cell producti on. The clinical problem is to being able to recognize the presence of other contributory f actors in pathogenesis of the anemia. Bone marrow macrophages fail to pass their stored iro n to developing RBCs and a lower than expected rise in erythropoietin suggesting some inhib ition in its pathway. Marrow also appears less responsive to Epo. 4 IL-1 has been identifie d. Detailed studies suggest a synergistic effect of IL-1 with T-cells to produce IFN-g whic h can suppress erythroid activity. May also be 4 levels of TNF-a which inhibits erythropoie sis through release of IFN-b from marrow stromal cells. Typical features of ACD 2 Hb range 7.0 \200\22311.0g/dL. 2 MCV is usually 6 but when longst anding the MCV is moderately 5 (may look like iron deficiency). 2 Ferritin usually 6 but may be 4. 2 Serum iron 6 or 5, TIBC 6 or 5. 2 Serum transferrin re ceptor levels normal. 2 Bone marrow Fe stores plentiful. Additional mechanisms of anemia in rheumatoid disease Autoimmune phenomena Warm antibody AIHA in association with rheumatoid and other collagen disorders; movie will show reticulocytosis and +ve DAT Red ce ll aplasia Drug related problems Chronic blood loss (caused by medication) Drug side effects e.g. macrocytosis from antimeta bolite immunosuppressives, e.g. azathioprine and methotrexate, oxidative haemolysis seconda ry to dapsone or sulfasalazine (occurs in normal individuals as well as those with G6PD def iciency) Anemia secondary to gold therapy for rheumatoid arthritis Idiosyncratic reactions, unexplained or unforeseeable reactions such as marrow aplasia Rare autoimmune haemolysis d ue to mefenamic acid, diclofenac or ibuprofen 2 to other organ problems Hypersplenism, Felty \200\231s syndrome in rheumatoid, renal failure in SLE or polyarteritis 02-red cell disorders.qxd 10.12.2003 04.10 PM Page 51 Red cell disorders Management Supportive transfusion in symptomatic patients; coexistent Fe deficiency should be excluded and treated. Minority may be suitable for/responsive to erythropoietin therapy. 51 Bleeding and iron deficiency Usually secondary to use of NSAIDs \200\224consider and exclu de other causes of blood loss which may occur in this patient group. Bron, D., Meuleman, N. & Mascaux, C. (2001) Biological basis of anemia. Semin Oncol, 28, 1 \200\2236. 02-red cell disorders.qxd 10.12.2003 04.10 PM Page 52 Anemia in gastrointestinal disease Anemia occurs in GIT disorders through mechanisms of blood loss, anemia of chronic disease (ACD), specific disease-related complications or drug side effects/idiosyncrasy occurring s ingly or in various combina- tions. 52 Blood loss in gastrointestinal disease Acute Immediately following acute hemorrhage \200\224RBC indices usually normal Normochromic anem ia RBC indices show low normal or marginally 5, especially MCV Movie shows mixture of normo chromic & hypochromic RBCs ( \200\230dimorphic \200\231) Acute on chronic Chronic RBC indices show established chronic Fe deficiency features 5 MCV, MCH, platelets often 4 Anemia in GIT disorders can be simply considered against some of the commoner problems aris ing through the GIT: Oesophageal \200\224bleeding oesophageal web and chronic Fe deficiency. from peptic oesophagitis, association of Gastric \200\224pernicious anemia and B12 deficiency, late effects of partial or total gas trectomy producing B12 and/or Fe deficiency. Microangiopathic haemolytic anemia from metast atic adenocarcinoma. Small bowel \200\224malabsorption states e.g. Fe and/or folate deficiency 2 to coeliac di sease, malabsorption including inflammatory bowel disease; hyposplenism secondary to coelia c with or without 4 platelets. Large bowel \200\224blood loss anemia from inflammatory bow el disorders. Note: these may also be associated with ACD. Rare occurrence of autoimmune ha emolysis associated with ulcerative colitis. from other problems Pancreas \200\224anemia of chronic disease associated with carcinoma or chronic pancreatit is, DIC associated with acute pancreatitis. Liver \200\224see p54. Drug related anemia arises through 2 Upper GIT irritation causing blood loss \200\224aspir in, NSAIDs, corticos- teroids. 2 Bleeding due to specific drugs e.g. warfarin and heparin. 2 Drug-induced haemolysis e.g. oxidative (Heinz body) haemolysis due to sulphasalazine or dapsone. 2 Production impairment e.g. aplasia secondary to mesalazine. 02-red cell disorders.qxd 10.12.2003 04.10 PM Page 53 Red cell disorders 53 02-red cell disorders.qxd 10.12.2003 04.10 PM Page 54 Anemia in liver disease Anemia is common in chronic liver disorders. There are several possible causes including: 2 Anemia of chronic disease \200\224part of marrow response to chronic inflammatory processes. 54 2 Macrocytosis anemia: specific effects on membrane lipids cause 4 MCV. 2 Alcohol \200\224direct suppressive effect on erythropoiesis with 4 MCV. 2 Folate deficien cy: seen in alcoholic liver disease7nutritional deficiency and/or direct effect of alcohol on folate metabolism. 2 Blood loss from oesophageal varices7acute or chronic anemia. 2 Hypersplenism \200\224port al hypertension can produce marked splenic enlargement leading to hypersplenism. 2 Haemolytic anaemias e.g. \200\223 Autoimmune haemolytic anemia in association with chronic active hepatitis. \200\223 Zieve \200\231s syndrome (hypertriglyceridaemia + self-limiting haemolysis due to acute alcohol excess). \200\223 Viral hepatitis may provoke oxidative haemolysis in those with G6PD deficiency. \200\223 Acute liver failure \200\224DIC and MAHA may occur. \200\223 Acanthocytosis: acu te haemolytic anemia with acanthocytosis (spur cell anemia). Rare. Usually late stage liver disease, with poor prognosis. 02-red cell disorders.qxd 10.12.2003 04.10 PM Page 55 Red cell disorders 55 02-red cell disorders.qxd 10.12.2003 04.10 PM Page 56 Iron de \201ciency anemia Microcytic anemia is common and the commonest cause is chronic iron deficiency. Iron physiology and metabolism Normal (Western) diet provides @15mg of iron/d, of which 5 \200\22310% is absorbed in duodenum and upper jejunum. Ferrous (Fe2+) iron is better absorb ed than ferric (Fe3+) iron. Total body iron store @ 4g. Around 1mg of iron/d lost in urine, feces, sweat and cells shed from the skin and GIT. Iron deficiency is commoner in 3 of rep roductive age since menstrual losses account for 20mg Fe/month and in pregnancy an additio nal 500 \200\2231000mg Fe may be lost (transferred from mother7fetus). 56 Causes of iron deficiency Reproductive system Menorrhagia GI tract Oesophagitis, oesophageal varices, hiatus hernia (ulcerated), peptic ulcer, inflammatory bo wel disease, hemorrhoids, carcinoma: stomach, colorectal, (rarely angiodysplasia, hereditar y haemorrhagic telangiectasia) Malabsorption Coeliac disease, atrophic gastritis (note: may also result from Fe deficiency), gastrectomy Physiological Growth spurts, pregnancy Dietary Vegans, elderly Genitourinary system Haematuria (uncommon cause) Others PNH, frequent venesection e.g. blood donation Worldwide Commonest cause is hookworm infestation Assessment Clinical history \200\224review potential sources of blood loss, especially GIT loss. Menstrual loss \200\224 quantitation may be difficult; ask about number of tampons used per day, how often these require changing, and duration. Other sources of blood loss e.g. haematuria and haemoptysis (these are not common causes of iron deficiency). Ask patient if he/she has been a blood donor \200\224regular blood dona tion over many years may cause chronic iron store depletion. Drug therapy e.g. NSAIDs and corticosteroids may cause GI irritation and blood loss. Past m edical history e.g. previous gastric surgery (7malabsorption). Ask about previous episodes of anemia and treatments with iron. 02-red cell disorders.qxd 10.12.2003 04.10 PM Page 57 Red cell disorders In patients with iron deficiency assume underlying cause is blood loss until proved otherwi se. In developed countries pure dietary iron lack causing iron deficiency is almost unknown . 57 Examination 2 General examination including assessment of mucous membranes (e.g. hereditary haemorrhagic telangiectasia). 2 Seek possible sources of blood loss. 2 Abdominal examination, rectal examination and sigm oidoscopy mandatory. 2 Gynecological examination also required. Laboratory tests 2 Hb 5. 2 5 MCV (<76FLz) and 5 MCHC (note: 5 MCV in thalassaemia and ACD). 2 Red cell distribution width (RDW): 4 in iron deficiency states with a greater frequency than in ACD or thalassaemia trait. 2 Serum ferritin (measurement of iron/TIBC generally unhelpful). Ferritin assay preferred \200\224a low serum ferritin identifies the presence of iron defi ciency but as an acute phase protein it can be 4, masking iron deficiency. 5iron and 4TIBC indicates iron deficiency. 2 The soluble transferrin assay (sTfR) is useful in cases where 4 ESR. sTfR is 4 in iron de ficiency but 6 in anemia in presence of 4 ESR (e.g. rheumatoid, other inflammatory states). This assay is not univer- sally available at present. 2 % hypochromic RBCs \200\224some modern analysers provide this para- meter. 4% hypo RBCs are seen in iron deficiency but also thalassaemia, CRF on Epo where ins ufficient iron given. 2 Zinc protoporphyrin (ZPP) \200\224in the absence of iron, zinc is incorpo- rated into protoporphyrin and can be measured. 2 Examination of BM aspirate (iron stain) is occasionally useful. 2 Theoretically FOB testi ng may be of value in iron deficiency but results can be misleading. False +ve results seen in high dietary meat intake. Blood movie in iron deficiency anemia: note pale red cells with pencil cell (top left). 02-red cell disorders.qxd 10.12.2003 04.10 PM Page 58 Treatment of iron deficiency Simplest, safest and cheapest treatment is oral ferrous salts, e.g. FeSO4 (Fe gluconate and fumarate equally acceptable). Provide an oral dose of ele- me ntal iron of 150 \200\223200mg/d. Side effects in 10 \200\22320% patients (e.g. abdom- inal distension, constipation and/or diarrhea) \200\224try 5 the daily dose to bd or od. Liqui d iron occasionally necessary, e.g. children or adults with swal- lowing difficulties. Incr easing dietary iron intake has no routine place in the management of iron deficiency except where intake is grossly deficient. 58 Response to replacement A rise of Hb of 2.0g/dL over 3 weeks is expected. MCV will 4 concom i- tantly with Hb. Reticulocytes may 4 in response to iron therapy but is not a reliable in dicator of response. Duration of treatment Generally 6 months. After Hb and MCV are normal continue iron for at least 3 months to replenish iron stores. Failure of response 2 Is the diagnosis of iron deficiency correct? \200\223 Consider anemia of chronic disorders or thalassaemia trait. 2 Is there an additional complicating illness? \200\223 Chronic infection, collagen disorder or neoplasm. 2 Is the patient complying with prescribed medication? 2 Is the preparation of iron adequate in dosage and/or formulation? 2 Is the patient continuing to bleed excessively? 2 Is there malabsorption? 2 Are there ot her haematinic deficiencies (e.g. B12 or folate) present? 2 Reassess patient: ?evidence of continued blood loss or malabsorption. Parenteral iron Occasionally of value in genuine iron intolerance, if compliance is a probl em, or if need to replace stores rapidly e.g. in pregnancy or prior to major surgery. Note: Hb will rise no faster than with oral iron. Intravenous iron Iron may be administered IV as iron hydroxide sucrose complex. Intramuscular iron e.g. iron sorbitol citrate. Usually 10 \200\22320 IM injections over se veral week period (note: injections painful and lead to long-term skin discoloration at the injection site). Best avoided. Andrews, N.C. (1999) Disorders of iron metabolism. N Engl J Med, 341, 1986 \200\2231995; Ku hn, L.C. & Hentze, M.W. (1992) Coordination of cellular iron metabolism by post-transcripti onal gene regu- lation. J Inorg Biochem, 47, 183 \200\223195; Tapiero, H., Gate, L. & Tew, K.D. (2001) Iron: deficiencies and requirements. Biomed Pharmacother, 55, 324 \200\223332. 02-red cell disorders.qxd 10.12.2003 04.10 PM Page 59 Red cell disorders 59 02-red cell disorders.qxd 10.12.2003 04.10 PM Page 60 Vitamin B12 de \201ciency B12 deficiency presents with macrocytic, megaloblastic anemia ra nging from mild to severe (Hb <6.0g/dL). Symptoms are those of chronic anemia, i.e. fatigue , dyspnoea on effort, etc. Neurological symptoms may also be present \200\224classically p eripheral paraesthesiae and disturbances of position and vibration sense. Occasionally neur ological symptoms occur with no/minimal hematological upset. If uncorrected, the patient ma y develop subacute combined degeneration of the spinal cord7perma- nently ataxic. 60 Pathophysiology B12 (along with folic acid) is required for DNA synthesis; B12 is also requ ired for neurological functioning. B12 is absorbed in terminal ileum after binding to intri nsic factor produced by gastric parietal cells. Body stores of B12 are 2 \200\2233mg (suffi cient for 3 years). B12 is found in meats, fish, eggs and dairy produce. Strictly vegetaria n (vegan) diets are low in B12 although not all vegans develop clinical evidence of deficie ncy. Presenting hematological abnormalities 2 Macrocytic anemia (MCV usually >110fL). In extreme cases RBC anisopoikilocytosis can result in MCV values lying just within normal range. 2 RBC changes include oval macrocytosis, poikilocytosis, basophilic stip- pling, Howell \200\223Jolly bodies, circulating megaloblasts. 2 Hypersegmented neutrophils. 2 Leucopenia and thrombocytopenia common. 2 Bone marrow shows megaloblastic change; marked erythroid hyper- plasia with predominance of early erythroid precursors, open atypical nuclear chromatin patterns, mitotic figures and \200\230giant \200\231 metamyelocytes. 2 Iron stores usually 4. 2 Serum B12 5. 2 Serum/red cell folate usually 6 or 4. 2 LDH level s markedly 4 reflecting ineffective erythropoiesis. 2 Autoantibody screen in pernicious ane mia: 80 \200\22390% show circulating gastric parietal cell antibodies, 55% have circulating intrinsic factor anti- bodies. Note: parietal cell antibodies are not diagnostic since found in normals; IFA is only found in 5 0% of patients with PA but is diagnostic. Causes of B12 deficiency Pernicious anemia Commonest, due to autoimmune gastric atrophy resulting in loss of intrinsic factor producti on required for absorp- tion of B12. Incidence increases >40 years and often associated wit h other autoimmune problems, e.g. hypothy- roidism. Following total gastrectomy May develop after major partial gastrec- tomy. Ileal disease Resection of ileum, Crohn \200\231s disease. 02-red cell disorders.qxd 10.12.2003 04.10 PM Page 61 Red cell disorders Blind loop syndromes E.g. diverticulae or localized inflamma- tory bowel changes allowing bacterial overgrowth w hich then competes for available B12. Diphyllobothrium latum. 61 Fish tapeworm Malabsorptive disorders Tropical sprue, coeliac disease. Dietary deficiency E.g. vegans. Management of B12 deficiency 1. 2. Above investigations are undertaken and a test of B12 ab sorption is carried out (e.g. Schilling test). Urinary excretion of a test dose of B12 labe led with trace amounts of radioactive cobalt is compared with excretion of B12 bound to int rinsic factor*; the test is done in two parts. B12 malabsorption corrected by intrinsic fac tor is diagnostic of pernicious anemia (in absence of previous gastric surgery). Identify and correct cause if possible. 3. Management \200\224hydroxocobalamin 1mg IM and folic acid PO should be given immediately. 4. Supportive measures \200\224bed rest, O2 and diuretics may be needed while awaiting res ponse. Transfusion is best avoided but 2 units of con- centrated RBCs may be used for patie nts severely compromised by anemia (risk of precipitating cardiac failure); hypokalaemia is occasion- ally observed during the immediate response to B12 and serum [K+] should be moni tored. 5. Response apparent in 3 \200\2235d with reticulocyte response of >10%; normoblastic conve rsion of marrow erythropoiesis in 12 \200\22324h. Patients frequently describe a subjective improvement within 24h. 6. B12 replacement therapy \200\224initially hydroxocobalamin 5 1mg IM should be given during the first 2 weeks, thereafter maintenance injec- tions are needed 3-monthly. If diet ary deficiency seems likely and B12 deficiency mild, worth trying oral B12 (cyanocobalamin 50 \200\223150mg or more, daily between meals) 8. Long term follow-up depends on the primar y cause. Pernicious anemia patients require lifelong treatment and should be checked annual ly with a full blood count and thyroid function; the incidence of gastric cancer is twice a s high in these patients compared to the normal population. 7. 9. Broad spectrum antibiotics should be given to suppress bacterial over- growth in blind l oop syndrome local surgery if appropriate. Long term IM B12 may be the pragmatic solutio n if blind loop cannot be cor- rected. Worldwide shortage of intrinsic factor at present, due to worries about human prion disease . This means that only part I Schilling test available in most centers. Guidelines on the investigation and diagnosis of cobalamin and folate deficiencies. A publi cation of the British Committee for Standards in Hematology. BCSH General Hematology Test F orce (1994). Clin Lab Haematol, 16, 101 \200\223115; Toh, B.H., van Driel, I.R. & Gleeson, P.A. (1997) Pernicious anemia. N Engl J Med, 337, 1441 \200\2231448. 02-red cell disorders.qxd 10.12.2003 04.10 PM Page 62 Folate de \201ciency Folate deficiency represents the other main deficiency cause of mega- loblastic anemia; hem atological features indistinguishable from those of B12 deficiency. Distinction is on basis of demonstration of reduced red cell and serum folate. 62 (cid:2)(cid:2) Megaloblastic anemia patients should never receive empirical treat- ment wit h folic acid alone. If they lack B12, folic acid is potentially capable of precipitating su bacute combined degeneration of the cord. Pathophysiology Adult body folate stores comprise 10 \200\22315mg; normal daily requirement s are 0.1 \200\2230.2mg, i.e. sufficient for 3 \200\2234 months in absence of exogenous fol ate intake. Folate absorption from dietary sources is rapid; proximal jejunum is main site of absorption. Main dietary sources of folate are liver, green vegetables, nuts and yeast. Western diets contain 0.5 \200\2230.7mg folate/d but availability may be lessened as folat e is readily destroyed by cooking, especially in large volumes of water. Folate coenzymes a re an essential part of DNA synthesis, hence the occurrence of megaloblastic change in defi ciency. Diagnosis Hematological findings are identical to those seen in B12 deficiency \200\224 ma crocytic, megaloblastic anemia. Other findings also similar to B12 except parietal cell and intrinsic factor autoantibodies usually \200\223ve. Reduced folate levels \200\224serum folate levels reflect recent intake, red cell folate levels give a more reliable indication of folate status. Causes of folate deficiency 55 intake Poor nutrition, e.g. poverty, old age, \200\230skid row \200\231 alcoholics. Pregnancy, 4 cell turnover, e.g. haemol- ysis, exfoliative dermatitis, renal dialysis. 4 requirements/losses Malabsorption Coeliac disease, tropical sprue, Crohn \200\231s and other malabsorptive states. Drugs Phenytoin, barbiturates, valproate, oral contraceptives, nitrofurantoin may induce folate m alabsorption. Antifolate drugs Methotrexate, trimethoprim, pentami- dine antagonize folate cf. induce defi- ciency. Alcohol Poor nutrition plus a direct depressant effect on folate levels which can precipi- tate cli nical folate deficiency. Management 1. Treatment and support of severe anemia as for B12 deficiency. 02-red cell disorders.qxd 10.12.2003 04.11 PM Page 63 Red cell disorders 2. Folic acid 5mg/d PO (never on its own \200\224see above), unless patient known to have normal B12 level. 3. Treatment of underlying cause e.g. in coeliac disease folate levels and absorption norma lize once patient established on gluten-free diet. Long term supplementation advised in chr onic haemolysis e.g. HbSS or HS. 4. Prophylactic folate supplements recommended in pregnanc y and other 63 states of increased demand e.g. prematurity. Blood movie: normal neutrophil: usually has <5 lobes. This one has 3 lobes. Hypersegmented neutrophils with 7 \200\2238 lobes: found in B12 or folate deficiency. Note: blood films and marrow appearances are identical in B12 and folate deficiencies. 02-red cell disorders.qxd 10.12.2003 04.11 PM Page 64 Other causes of megaloblastic anemia Megaloblastic anemia not due to actual deficiency of either B12 or folate is uncommon, but may occur in the following situations. 64 Congenital 2 Transcobalamin II deficiency \200\224absence of the key B12 transportation protein results in severe megaloblastic anemia (will correct with par- enteral B12). 2 Congenital intrinsic factor deficiency \200\224autosomal recessive, results in failure t o produce intrinsic factor. Presents as megaloblastic anemia up to age of 2 years and respo nds to parenteral B12. 2 Inborn errors of metabolism \200\224errors in folate pathways, also occurs in orotic aciduria and Lesch \200\223Nyhan syndrome. 2 Megaloblastosis commonly present in the congenital dyserythropoietic anaemias ((cid:9) p450). Acquired 2 MDS \200\224often present in sideroblastic anemia (RARS). 2 Acute leukemia \200\224megaloblastic-like erythroid dysplasia in AML M6. 2 Drug induced \200\224secondary to antimetabolite drugs including 6-mercap- topurine, cytosine arabinoside, zidovudine and hydroxyurea. 2 Anesthetic agents \200\224transient megaloblastic change after nitrous oxide. 2 Alcohol excess \200\224may result in megaloblastic change in absence of measurable folate deficiency. 2 Vitamin C deficiency \200\224occasionally results in megaloblastic change. 02-red cell disorders.qxd 10.12.2003 04.11 PM Page 65 Red cell disorders 65 02-red cell disorders.qxd 10.12.2003 04.11 PM Page 66 Anemia in other de \201ciency states Iron, folate or vitamin B12 deficiencies account for the majority of clinically significant deficiency syndromes resulting in anemia. Anemia is recog- nised as a complication in othe r vitamin deficiencies and in malnutrition. Vitamin A deficiency Produces chronic disorder like iron deficiency anemia with 5 MCV and M CH. 66 Vitamin B6 (pyridoxine) deficiency Can produce hypochromic microcytic anemia; sideroblastic change may occur. Pyridoxine is given to patients on antituberculous therapy with iso- nia zid which is known to interfere with vitamin B6 metabolism and cause sideroblastic anemia. Vitamin C deficiency Occasionally associated with macrocytic anemia ( megaloblastic chang e in 10%); since the main cause of vitamin C deficiency is inadequate diet or nutrition the re may be evidence of other deficiencies. Vitamin E deficiency Occasionally seen in the neonatal period in low birth weight infants \200\224 results in haemolytic anemia with abnormal RBC morphology. Starvation Normochromic anemia leucopenia occurs in anorexia nervosa; fea- tures are not associated with any specific deficiency; bone marrow is typi- cally hypocellular. 02-red cell disorders.qxd 10.12.2003 04.11 PM Page 67 Red cell disorders 67 02-red cell disorders.qxd 10.12.2003 04.11 PM Page 68 Haemolytic syndromes Definition Any situation in which there is a reduction in RBC life-span due to 4 RBC destru ction. Failure of compensatory marrow response results in anemia. Predominant site of RBC d estruction is red pulp of the spleen. 68 Classification \200\2243 major types Hereditary vs. acquired 1. Immune vs. non-immune 2. E xtravascular vs. intravascular 3. Hereditary cause suggested if history of anemia refractory to treatment in infancy FH e. g. other affected members, anemia, gallstones, jaundice, splenectomy. Acquired haemolytic a nemia is suggested by sudden onset of symptoms/signs in adulthood. Intravascular haemolysis \200\224takes place in peripheral circulation cf. extravascular haemolysis which occurs i n RES. Hereditary 2 Red cell membrane disorders e.g. HS and hereditary elliptocytosis. 2 Red cell enzymopathies e.g. G6PD and PK deficiencies. 2 Abnormal Hb e.g. thalassaemias and sickle ce ll disease, unstable Hbs. Acquired \200\223immune Alloimmune 2 HDN 2 RBC transfusion incompatibility Autoimmune 2 Warm AIHA \200\2231 or 2 to SLE, CLL, drugs 2 Cold \200\223Mycoplasma or E BV infection, 2 Cold haemagglutinin disease (CHAD) 2 Lymphoproliferative disorders 2 Paroxy smal cold haemoglobinuria (PCH) Acquired \200\223non-immune 2 MAHA 2 TTP/HUS 2 Hypersplenism 2 Prosthetic heart valves 2 Ma rch haemoglobinuria 2 Sepsis 2 Malaria 2 Paroxysmal nocturnal haemoglobinuria Clinical features Symptoms of anemia e.g. breathlessness, fatigue. Urinary changes e.g. red or dark brown of haemoglobinuria. Symptoms of underlying disorder. Confirm haemolysis is occurring 2 Check FBC. 2 Peripheral blood movie \200\224polychromasi a, spherocytosis, fragmentation (schistocytes), helmet cells, echinocytes. 2 4 reticulocytes. 2 4 serum bilirubin (unconjugated). 2 4 LDH. 02-red cell disorders.qxd 10.12.2003 04.11 PM Page 69 Red cell disorders 2 Low/absent serum haptoglobin (bind free Hb). 2 Schumm \200\231s test (for intravascular h aemolysis). 2 Urinary haemosiderin (implies chronic intravascular haemolysis e.g. 69 PNH). Discriminant diagnostic features Establish whether immune or non-immune \200\224check DAT ?Immune if DAT +ve check IgG and C3 specific reagents \200\224suggest warm and cold antibo dy respectively. Screen serum for red cell alloantibodies. ?Cold antibody present \200\224examine blood movie for agglutination, check MCV on initial FBC sample and again after incubation at 37 C for 2h. High MCV at room temperature due to agglutinates falls to normal at 37 C. Check anti-I and anti-i titres for confirmation. Ch eck Mycoplasma IgM and EBV serology, and for presence of Donath Landsteiner antibody (cold reacting IgG antibody with anti-P specificity). ?Warm antibody present \200\224IgG +ve DAT only suggestive \200\224examine movie for sphe rocytes (usually prominent), lymphocytosis or abnormal lymphs to suggest LPD. Examine patie nt for nodes. ?Intravascular haemolysis \200\224check for urinary haemosiderin, Schumm \200\231s test. ?Sepsis \200\224check blood cultures. ?Malaria \200\224examine thick and thin blood films for parasites. ?Renal/liver abnormality \200\224examine for hepatomegaly, splenomegaly, LFTs and U&E. ?Low platelets \200\224consider TTP/HUS. ?Haemoglobinopathy \200\224check Hb electrophoresis. ?Red cell membrane abnormality \200\224check family history and perform red cell fragility test. ?Red cell enzyme disorder \200\224check family history and do G6PD and PK assay. Note: enz ymes may be falsely normal if reticulocytosis. ?PNH \200\224check immunophenotyping for CD55 + CD59 (Ham \200\231s acid lysis test now la rgely obsolete). Treatment Treat underlying disorder. Give folic acid and iron supplements if low. 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 70 Genetic control of hemoglobin production Hb comprises 4 protein subunits (e.g. adult Hb = 2 a + 2 b chains, a2b2) each linked to a haem group. Production of different globin chains varies from embryo7adult to meet the particular environment at each stage. Globin genes are located on chromosomes 11 and 16. A ll globins related to a globin are located on chromosome 16; all those related to b globin are on chromosome 11. The sequence in which they are produced during development reflects t heir physical order on chromosomes such that z is the first a-like globin to be produced in life. After z expression stops, a production occurs (z7a switch). On chromosome 11 the arr angement of b-like globin genes follows the order (from left7right) e7g7d7b mirroring the b -like globin chains produced during devel- opment. As embryo develops into fetus, z product ion stops and a is pro- duced. The a globin combines with g chains and produces a2g2 (fetal Hb, HbF). After birth g production 5 and d and b chains are produced. Adults have predomin antly HbA (a2b2) although small amounts of HbA2 (a2d2) and HbF are produced. 70 Hb switching is physiological but the mechanism is unclear. HbF (a2g2) binds O2 more tightl y than adult hemoglobin, ensuring adequate O2 delivery to the fetus which must extract its O2 from mother \200\231s circulation. After birth the lungs expand and the O2 is derived fr om the air, with b production replacing that of g, leading to an increase in adult hemoglob in (a2b2). Hemoglobin Globin chains Amount Embryo Hb Gower 1 Hb Gower 2 Hb Portland *by 5th week z2e2 a2e2 z2g2 42%* 24%* Fetus HbF HbA a2g2 a2b2 85% 5 \200\22310% Adult HbA HbA2 HbF a2b2 a2d2 a2g2 97% 2.5% 0.5% Hemoglobin abnormalities Fall into 2 major groups: structural abnormalities of Hb due to al terations in DNA coding for the globin protein leading to an abnormal amino acid in the glo bin molecule, e.g. sickle hemoglobin (bS). Second group of Hb dis- orders results from imba lanced globin chain production \200\224globins pro- 02-red cell disorders.qxd 10.12.2003 04.11 PM Page 71 Red cell disorders duced are structurally normal but their relative amounts are incorrect and lead to the thal assaemias. 71 Haemoglobinopathies result in significant morbidity and mortality on a world-wide scale. Pa tients with these disorders are also seen in Northern Europe and the UK, especially in area s with significant Greek, Italian, Afro- Caribbean and Asian populations. a-like genes on chromosome 16 z yz ya2 (cid:2)(cid:3)1 a2 a1 (cid:4)-like genes on chromosome 11 e Gg Ag yb d b Arrangement of a-like and b-like globin genes (y indicates pseudogene) a globin switching z yz ya2 ya1 a2 a1 b globin switching e Gg Ag yb d b Globin gene switching during development 02-red cell disorders.qxd 10.12.2003 04.11 PM Page 72 Sickling disorders Sickle cell anemia (homozygous SS, bSbS), HbSC (bSbC), HbS/b+ or b thalassaemia, and HbSD (bSbD) all produce significant symptoms but homozygous sickle cell anemia is generally the most severe. The gene has remained at high frequency due to conferred resistance to malari a in het- erozygotes. Inheritance is autosomal recessive. 72 Sickle cell anemia (SCA, HbSS) Pathogenesis Widespread throughout Africa, Middle East, part s of India and Mediterranean. Single base change in b globin gene, amino acid 6 (glu7val). In UK Afro-Caribbean population gene is found in 1:10. RBCs containing HbS deform (elongat e) under conditions of reduced oxy- genation, and form characteristic sickle cells \200 \224do not flow well through small vessels, and are more adherent than normal to vascular e ndothe- lium, leading to vascular occlusion and sickle cell crises. Patients with SCA are t he offspring of parents both of whom are carriers of the bS gene, i.e. they both have sickl e cell trait, and homozygotes for the abnormal bS gene demonstrate features of chronic red cell haemolysis and tissue infarction. Clinical features Highly variable. Many have few symptoms whilst others have severe and fre quent crises, marked haemolytic anemia and chronic organ damage. HbF level plays role in am eliorating symptoms (4 HbF7fewer and milder crises). History may reveal a +ve family histor y or past history of crises. 2 Infancy \200\224newborns have higher HbF level than normal adult, pro- tected during first 8 \200\22320 weeks of life. Symptoms start when HbF level falls. SCA of ten diagnosed <1 year. 2 Infection \200\224high morbidity and mortality due to bacterial and viral infection. Pneumococcal septicaemia (Streptococcus pneumoniae) well recognized. Other infec ting organisms: meningococcus (Neisseria menin- gitidis), Escherichia coli and Haemophilus influenzae (hyposplenic). 2 Anemia \200\224children and adults often severely anemic (Hb 6.0 \200\2239.0 g/dL). Ane mia is chronic and patients generally well-adapted until episode of decompensation (e.g. se vere infection) occurs. Sickle crises 2 Vaso-occlusive \200\224dactylitis, chest syndrome and girdle syndrome. Patients complain of severe bone, joint and abdominal pain. Bone pain affects long bones an d spine, and is due to occlusion of small vessels. Triggers: infection, dehydration, alcoho l, menstruation, cold and tem- perature changes \200\223 often no cause found. 2 Dactylitis \200\224mainly children. Metacarpals, metatarsals, backs of hands and feet sw ollen and tender (small vessel occlusion and infarction). Recurrent, can result in permanen t radiological abnormalities in bones of the hands and feet (rare). 2 Acute chest syndrome \200\224common cause of death. Chest wall pain, sometimes with pleu risy, fever and SOB. Resembles infection, infarc- tion or embolism. Requires prompt and vig orous treatment. Transfer to ITU if pO2 cannot be kept >70 mmHg on air. 10% mortality. Trea t infection vigorously, often due to S pneumoniae, H influenzae, Mycoplasma, Legionella. 02-red cell disorders.qxd 10.12.2003 04.11 PM Page 73 Red cell disorders 2 Aplastic crises \200\224sudden 5 in marrow production (esp. red cells).