Transcript Anaemia of
Anaemia Oliver Rácz, 2015 Repetition of physiology and biochemistry • Red cell properties and function – Number, synthesis, life span, degradation • Haemoglobin structure and function – Structure, oxygen affinity and its regulation, variants, degradation • Iron metabolism – See trace element lecture • Vitamin B12 and folic acid Definition of anaemia Deficiency in the oxygen-carrying capacity of the blood due to diminished erythrocyte mass (THEORY) Low red cell count, Hb, HT (PRACTICAL MEDICINE) May be due to: Erythrocyte loss (bleeding, haemolysis) Decreased erythrocyte production Bone marrow dysfunction Low erythropoietin/high hepcidin Iron deficiency Vitamin B12, folic acid deficiency Indicators of anaemia • • • • • MEASURED ON AUTOMATIC ANALYZERS Haemoglobin, grams of Hb/liter of whole blood (or g/dL in USA) Hematocrit, ratio between cell and plasma volume RBC = millions/microliter (= mm3) of whole blood (or 1012/liter) MCV = Mean corpuscular volume (of 1 RBC) • > 100 femtoliter Macrocytes (1 fl = 10-15 liter) • 80 – 100 femtoliter Normocytes • < 80 femtoliter Microcytes • MCH = Mean corpuscular Hb (norm is 20 pg/cell; pico = 10-12) • RDW = Red blood cell distribution width – (Standard deviation of red cell volume/mean cell volume) × 100 – Normal value is 11-15% – If elevated, suggests large variability in sizes of RBCs Normal and decreased values • Hb (160) • Women: <120 • Men: < 135 severe <100 • Ht (0,45) • Women: < 0,36 • Men: < 0,41 severe < 0,30 Symptoms of Anaemia ? • Decreased oxygenation – – – – – Pallor Exertional dyspnea Dyspnea at rest Fatigue Decreased mental function • Decreased circulating volume – – – – Fatigue Muscle cramps Postural dizziness Syncope • Disease/condition specific, e.g. – Jaundice – Other FOR LONG TIME MOSTLY NOTHING, HIDDEN BEHIND THE BASIC DISEASE OR COMPENSATED NO CYANOSIS Special considerations • Acute Bleeding • Drop in Hb & Ht may not be shown until some time after acute blood loss (even though patient may be hypotensive) • WHY??? • Later reticulocytosis • Pregnancy • In third trimester, RBC and plasma volume are expanded but there is a bigger expansion of plasma volume than of red cell mass. • Lab values show reductions in Hb, Ht, and RBC count, often to pathological levels, but according to RBC mass this is a haemodilution and not anaemia. • BUT! Real anaemia is also frequent in gravidity • Volume Depletion • Patient’s who are severely volume depleted may have physiological Ht results and do not show anaemic values until rehydrated !!! RBC Life Cycle • In the bone marrow, erythropoietin enhances the growth of differentiation of burst forming unitserythroid (BFU-E) and colony forming units-erythroid (CFU-E) into reticulocytes. • Reticulocytes spend ≈ 3 days maturing in the marrow, and ≈ 1 day maturing in the peripheral blood (reticulocyte count ≈ 0,5% of RBCs). • After blood loss or haemolysis increased % of reticulocytes if bone marrow is OK • Mature RBCs circulate in the peripheral blood for 120 days. Under steady state conditions, the rate of RBC production equals the rate of RBC loss. (Around 1/120 ≈ 0,8 % of cells/day. Iron recycling!) Erythrocyte loss - bleeding • Acute/Haemodynamically significant (not a haematological problem in general practice) • • • • Injury (shock!) Gastrointestinal (ulcus, oesophagus, polyps…) Retroperitoneal Hemophilia and other coagulation disorders • Chronic • kidney, abnormal menstrual cycle, ulcer disease in the past • If not treated it can transform to iron deficiency anaemia Haemolysis • • • • • • • Osmotic – only in test tube (distilled water) Mechanical – artificial heart valves (past) Streptococcus haemolyticus ? ABO or Rh incompatibility Malaria, Babesiosis, and many others Autoimmune, toxic Inherited – Hb S and other Hbpathies, thalassemia, membranopathies, enzymopathies Some forms of haemolytic anaemia • • Hereditary spherocytosis Glucose-6-phosphate dehydrogenase (G6PD) Deficiency • Autoimmune Haemolytic Anaemia – • Most common enzyme defect in erythrocytes • X-linked • Brisk haemolysis when patients exposed to oxidative stress from drugs, infections or toxins. • Thrombotic Thrombocytopenic Purpura (TTP) • Thrombocytopenia and microangiopathic haemolytic Anaemia, fever, renal insufficiency, neurologic symptoms • Schistocytes on smear • Haemolytic Uremic Syndrome – • Infections – – – • Thrombocytopenia, Microangiopathic haemolytic Anaemia, renal insufficiency • Warm-antibody mediated • IgG antibody binds to erythrocyte surface • most common • Diagnosed by POSITIVE Coomb’s Test (detectgs IgG or complement on the cell surgace) • Can be caused drugs • Treated with corticosteroids or splenectomy if refractory Cold agglutinin Disease • IgM antibodies bind to erythrocyte surface • Does not respond to corticosteroids, but usually mild. Malaria Babesiosis Sepsis Trauma – Includes some snake, insect bites BABESIOSIS Anaemia due to Low erythropoietin • Kidney Disease (including diabetic nephropathy) – Normocytic – Low reticulocyte count – Target Hb for patients on dialysis: 110 -120 g/L • Administer erythropoietin • Good iron stores should be maintained – Peripheral smear in uraemic patients frequently show echinocytes Aplastic anaemia (bone marrow dysfunction) • • • • Radiation Toxic substances Drug side effects Leukaemias Iron deficiency • Iron Deficiency – Can result from: – – – – – – Pregnancy/lactation Normal growth Blood loss Intravascular haemolysis Gastric bypass Malabsorption » Iron is absorbed in proximal small bowel; decreased abosrption in celiac disease, inflammatory bowel disease – May manifest as „pica“ • Tendency to eat ice, clay, starch, crunchy materials – May have pallor, koilonychia of the nails, beeturia – Peripheral smear shows microcytic, hypochromic red cells with marked anisopoikilocytosis. Koilonychia Laboratory findings • Serum Iron • LOW • Total Iron Binding Capacity (TIBC) • HIGH • Soluble transferrin receptors • HIGH • Serum Ferritin • LOW • Can be “falsely”normal in inflammatory states Cobalamin deficiency • Macrocytic Anaemia (megaloblastic, in the past “pernicious” • Lab Values – Cobalamin level < 200 pg/mL – Elevated serum methylmalonic acid – Elevated serum homocysteine • Vit B12 binds to intrinsic factor in the small bowel in order to be absorbed – the pernicious form was an autoimmune condition blocking intrinsic factor • Vit. B12 is needed for DNA synthesis – The anaemia is only the tip of an “iceberg” • Deficiency can result in cardiac and neuropsychiatric symptoms – Spastic ataxia, psychosis, loss of vibratory sense, dementia – Dilated cardiomyiopathy • Smear shows macrocytosis and hypersegmentation of polymorphonuclear cells, with possible basophilic stippling. Folate deficiency • – Macrocytic Anaemia and a lot of other consequences (spina bifida) – Lab Values – Low folate – Increased serum homocystine – NORMAL methylmalonic acid – Often occurs with decreased oral intake, increased utilization, or impaired absorption of folate – Folate is normally absorbed in duodenum and proximal jejunum – deficiency found in celiac disease, regional enteritis, amyloidosis – Deficiency frequently in alcoholics, because enzyme required for deglutamation of folate is inhibited by alcohol. – Deficiency often found in pregnant women, persons with desquamating skin disorders, patients with sickle cell Anaemia (and other conditions associated with rapid cell division and turnover) – Smear shows macrocytosis with hypersegmented neutrophils – BE CAREFUL WITH FOLATE OVERDOSE Anaemia of „chronic disease“ • Usually normocytic, normochromic (but can become hypochromic, microcytic over time) • Occurs in people with inflammatory conditions such as collage vascular disease, malignancy or chronic infections • Iron replacement is not necessary • May benefit from erythropoietin supplementation. • HEPCIDIN BLOCKS RESORBTION – IRON IS A GROWTH FACTOR OF BACTERIA The anaemia of chronic disease the hepcidin story • Hepcidin – a 25 aminoacid peptide from liver discovered in 2001 • Ferroportin – a very specific transmembrane iron export system • Hepcidin injection: Serum Fe decrease by blocking the Fe export from cells storing iron • Hepcidin deficiency: High serum Fe – iron overload. • Inflammation – hepcidin elevated to block iron for microbes Normal peripheral „smear“ Echinocytes (“burr cells”) Iron deficiency anaemia MICROCYTIC Megaloblasts and hypersegmented neutrophil Spherocytosis TTP / HUS – microangiopathic haemolysis with schistocytes Malaria Babesiosis Sickle Cell Anaemia Lab Analysis in Haemolytic Anaemia • Increased indirect bilirubin • Increased LDH • Increased reticulocyte count • Normal reticulocyte count is 0.5 to 1.5% • > 3% is sign of increased reticulocyte production, suggestive of haemolysis • Reduced or absent haptoglobin • < 25 mg /dL suggests haemolysis • Haptoglobin binds to free haemoglobin released after haemolysis Evaluating the patient with Anaemia • Any history of medical problems that could cause Anaemia? – Sickle cell Disease? – Thalassemia? – Renal Disease? – Hereditary Spherocytosis? Evaluating the Patient with Anaemia • Are the other cell lines also low? – If WBC and platelets are both low, consider APLASTIC AnaemIA! – Check medication list » NSAIDS (phenylbutazone), Sulfonamides, Acyclovir, Gancyclovir, chloramphenicol, anti-epileptics (phenytoin, carbamazepine, valproic acid), nifedipine » Check parvovirus B19 IgG, IgM » Consider hepatitis viruses, HIV – If Platelets are low consider TTP or HUS! – Must check smear for schistocytes (for sign of microangiopathic haemolytic Anaemia) – If renal failure, E. Coli O157:H7 exposure → HUS – If renal failure, neurologic changes, fever → TTP Evaluating the Patient with Anaemia • Is the patient bleeding?! – Any bright red blood per rectum (hematochezia) or black tarry stools (melena)? • Check stool guaiac, may consider sigmoidoscopy or colonoscopy – Any abdominal pain, or recent faemoral vein/artery manipulation? • Consider retroperitoneal hematoma Evaluating the Patient with Anaemia • If other cell lines are okay, what is the MCV and RDW? – If MCV < 80, then it’s a microcytic Anaemia • Check serum iron, ferritin, TIBC – If iron-deficiency Anaemia, look for sources of chronic bleeding – heavy menstrual bleeding, consider colonoscopy • Consider lead poisoning, copper deficiency, thalassemias – If MCV 80-100, then it’s a normocytic Anaemia • Any inflammatory conditions that could result in Anaemia of chronic disease? • Consider checking indirect bili, LDH, haptoglobin, reticulocyte count – If MCV > 100, then it’s a macrocytic Anaemia • Check Vit. B 12, folate • Consider liver disease, alcoholism, myelodysplastic syndrome • Check medications: hydoxyurea, AZT, methotrexate Evaluating the Patient with Anaemia • Any jaundice, elevated bilirubin, suspicious for haemolysis? – Check for increased indirect bilirubin, increased LDH, decreased haptoglobin, increased reticulocyte count – Any sign of infection? Malaria? Babesiosis? – Is Coombs test positive? – If yes, may be warm antibody haemolytic Anaemia; Consider drug as cause