Hematology Flashcards
Reticulocyte count
1st step up in work-up in any anemia. Young RBC. Takes 24h -> mature one (biconcave). If low/inappropriate response, bone marrow problem. If high, not bone marrow problem b/c responding well. Takes 5-7 days for reticulocyte response.
Correct the reticulocyte count for the degree of anemia?
Corrected = HCT/45 * reticulocyte count. 3% or greater = good response
Reticulocyte
Still synthesizing Hgb. Black lines are RNA filament (w/ stain). POLYCHROMASIA (basophilic) = means that bone marrow is really responding and bringing out even younger cells. These cells take 2-3 days to mature. We don’t want polychromasia cells in our corrected reticulocyte count. DIVIDE by two if see polychromasia.
Rule of 3
Multiply hgb x 3 ~ HCT. BTW, transfusion of pRBC. For every unit of pRBC transfuse - hgb by 1 and HCT by 3%.
Fe deficiency anemia
Most common cause is GI bleed.
MCV
Mean corpuscular volume. MCV < 80 is microcytic. MCV > 100 is macrocytic (usu. B12 or folate). But what if dimorphic population, then MCV looks normal but you are not normal (RDW increased).
Fe, Folate, B12 absorption where?
Duodenum, jejunum, terminal ileum
RDW
Reports size distribution. Anemia doesn’t happen immediately. Developing microcytic anemia will give you a low MCV with higher RDW. Low MCV and higher RDW = Fe-deficiency. Can’t be thalassemia b/c genetic and congenital.
Spherocyte
Too little membrane. Spherocyte is an Anorexic cell. NO central pallor.
Target cell
Too MUCH membrane. Obese cell right in the middle more membrane and more hgb to be red. Markers for Alcoholics (Chol conc.) and hemoglobinopathy (thalassemia, sickle cell)
Microcytic anemia
GREATER area of pallor b/c less hgb.
Physical signs of anemia
Spoon nails (iron deficiency, koilonychia), cheilosis, pallor of conjunctiva, Lead line
Iron studies
4 studies: Serum Fe (100); Ferritin - soluble, circulating form of iron storage = iron stored in bone marrow; transferrin = carrying protein for Fe made in the liver;
Transferrin and TIBC
ARE THE SAME.
Fe storage and transferrin are related
When the Fe stores are deficient, signal for liver to make more TRANSFERRIN. TIBC increases in Fe-deficiency.
% Saturation
= Serum Fe / TIBC. Normal is 100/300 = 0.33.
Pathogenesis of microcytic anemia
Can’t make Hgb. Hb concentration in developing red blood cell that determines the # of cell division. If Hb is LOW, increases the number of mitoses. All 4 microcytic anemias have LOW Hb.
What makes hemoglobin is how you think of microcytic anemia?
Heme = Fe + protoporphyrin. HbA1 = alpha + beta. Alpha + Delta = A2. Alpha + gamma = Fetal.
Fe-deficiency anemia
No Fe to make Heme. Low hgb. Microcytic.
Anemia of chronic disease
Response to inflammation. Bacteria likes Fe, so decrease Fe availability. Fe is usually in MACROPHAGES in bone marrow. Lock away the Fe but lose the key. Serum Fe low. TIBC is LOW (high iron stores = dec. transferrin). %Sat = low. Serum ferritin = high.
Sideroblastic anemias
Sidero = Iron. Porphyrin synthesis begins in the mitochondria. 3 main causes: (1) EtOH (not the most common anemia in alcoholics) b/c it’s a mitochondrial poison that uncouples oxidative phosphorylation. Fe filled in mitochondria = RINGED sideroblast. And iron overload disease. (2) B6 deficiency (e.g. INH treatment) - no B6, no ALA-synthase. Fe can’t get out of mitochondria again = ringed sideroblast (3) Lead poisoning - lead denatures proteins, esp. FERROkelotase > ala dehydratase. And, again, Fe gets stuck in mitochondria.
Porphyrin synthesis
Succinyl-CoA + Glycine (btw inhibited by tetatnospasmin) -(ALA-synthase; pyridoxine)-> delta-aminolALA ->->->-(in mito)->protoporphyrin + Fe -(Ferrokelotase)-> Heme. Feedbacks against ALA-synthase.
Thalassemias
Genetic diseases AR.
Hb electrophoresis
HbA is 95%. HbA2 is 1-2%. HbF is 1%. PERCENTAGES.
Alpha-thalassemia
AR. Asian, Blacks. Problem in making alpha-globin chains. ALL hemoglobins are EQUALLY decreased. DOESNT show up on electrophoresis. 4 alpha-chain synthesis genes. Deletion of 1 = normal. 2 dels = minimal decrease; mild anemia; microcytic b/c the globin production is decreased (alpha-thalassemia minor). 3 dels = large decrease; 4 beta chains come together to make Hb H. (will show up on electrophoresis; Hb H disease). 4 dels = spontaneous abortion (usually). 4 Gammas = Hb Barts. In Asia, more spontaneous abortions -> more choriocarcinomas. Tx = NOT give Fe.
Beta-thalassemia
AR. Blacks, Greek, Italians. Beta chain decreased. B by itself = normal. B+ = not making a lot. B0= not making at all. SPLICING, STOP codons (most severe = Cooley’s anemia). Alpha, delta, gamma, okay. HbA DECREASES, HbA2 and HbF increase. WILL be on Hb electrophoresis. Tx = transfusion if most severe (but will die of Fe-overload).
Beta-delta thalassemia
Blacks. Only alpha and gammas are left. Hereditary Hb F disease. NO problems.
Causes of Fe-deficiency anemia
Prematurity = loses iron when NOT in utero. Preemies need Fe. Newborn = blood in stool (most of it usually mom’s). [e.g. bleeding Meckel’s diverticulum]. Woman < 50 = menorrhagia. Woman < 20 = anovulatory cycles. Men < 50: peptic ulcer disease. Men and women > 50: Colon Cancer. Fe low. TIBC is HIGH. %Sat = Fe/TIBC = LOW. Serum ferritin is low.
Fe studies in mild thalassemias
NORMAL
Ringed sideroblast
Prussian Blue in bone marrow. Not in smear.
Lead poisoning
“Coarse basophilic stippling.” B/c lead denatures ribonuclease -> persist ribosomes. VERY specific. On X-ray, deposits in epiphysis (failure to grow). Severe, abdominal colic, cerebral edema (increased vessel permeability and buildup of delta-ALA acid!) -> convulsion. Paint, cars, moonshine from radiators, pottery painter. Neuropathies.
Sideroblastic lab studies
Fe-overload (like hemochromatosis). Fe high. Fe stores are high. Transferrin/TIBC LOW. %Sat high. Ferritin high.
B12 and folate in DNA synthesis
dTMP. Not be able to mature the nucleus -> large cells (any of the nucleated cells - squamous, GI, etc.). Megaloblastic anemia.
B12 = cobalamin
B12 has cobalt.
Methyltetrahydrafolate
Circulating folate. B12 takes a methyl off of MTHF. THF and methylcobalamin. W/o B12, can’t get methyl off –> dec. DNA synthesis
Methylcobalamin does what?
Homocysteine + CH3 = methionine. Done by methylcobalamin. Methionine is used for 1C transfer reactions.
If you’re B12 or folate deficiency?
Homocysteine should be HIGH b/c it can’t be turned into methionine. Homocysteine produces thromboses 2/2 endothelial dmg. Folate deficiency is most common reason for high homocysteine.
Tetrahydrafolate
Thymidylate synthase makes dTMP.
Dihydrolate reductase
DHF -> THF. MTX, TMP, pyrimethamine.
Odd-chain fatty acid metabolism
B12 is involved with propionate metabolism. Cofactor for methylmalonyl CoA -> succinyl CoA (involved with myelin synthesis?). Methylmalonic acid is a very specific and sensitive test for B12 deficiency. Neurologic manifestations of B12 deficiency is due to build-up of FA metabolites -> myelin can’t be synthesized -> demyelination of lateral corticespinal and dorsal columns..
Normal metabolism of B12
Animal product. Pure vegetarians NEED B12 supplementation. Binds to R factor in saliva. Protect it from destruction by acid. Intrinsic factor made by parietal cells in the body-fundus. IF isn’t destroyed by acid. B12-R goes into duodenum where intrinsic factor around. R factor cleaved (requires Pancreas). B12 binds intrinsic factor –> terminal ileum -> receptors for intrinsic factor. (Same place where bile salts, Crohn’s disease). B12 has 6-9 yr supply
Etios of B12 deficiency
Most common is pernicious anemia. Destruction against parietal cells + other cells around = ATROPHIC gastritis. Achlorhidia -> predispose for gastric adenocarcinoma. Chronic alcoholics b/c of pancreatitis and can’t cleave R factor. Pure veg. Some tapeworm eats B12. Bacterial overgrowth (2/2 peristalsis problem; diverticular). Terminal ileal disease (aka Crohn’s). Will see hypersegmented neutrophil.
Folate
Animal AND plant products. In a polyglutamate form. Can’t be absorbed in jejunum. Enzyme converts (intestinal conjugase) turns it into mono-form. (Phenytoin blocks intestinal conjugase -> macrocytic anemia). Monoglutamate at jejunum. Two things prevent this absorption: (1) OCP (2) Alcohol. Main reason why alcoholics are folate deficient. Folate has 3-4 months supply. Hypersegmented neutrophils.
Why the anemia in B12/folate deficiency?
Cords of Bilroth in spleen. Fixed macrophages where RBC’s are caught. In BM, cells have to fit through small holes to get through sinusoids. Megaloblastic cells (b/c of DNA problems) have a HARD time getting out. Macrophages eat up the cells. Therefore, pancytopenia.
Schilling’s test
Test for localizing B12 deficiency. The cause. Give radioactive B12 by mouth. Urine 24h. If nothing came out, NO absorption of B12. NOW: Radioactive B12 + IF = urine + means pernicious anemia. If neg, 10-day broad spectrum. Try radioactive, if + in urine = bacterial overgrowth. If NEG, NOW get pancreatic extract + radioactive B12 = urine + means chronic pancreatitis. If Not, Crohn’s, tapeworm.
Normocytic anemias w/ low reticu count
Some etios - early Fe-deficiency and anemia of chronic disease. Still need to get a Ferritin (will detect before anemic). Etio - blood loss < 1 week. No reticulocyte up b/c it takes 5-7 days for BM to rev up. Etio - aplastic anemia = No Bone Marrow. Pancytopenia. Idiopathic. Etio - decreased EPO 2/2 chronic renal failure. Etio - malignancy
Etios of aplastic anemia
Drugs - chloramphenicol, indomethacin, phenylbutozone, thyroid drugs. Infections - HEPATITIS C, Parvovirus (if only RBC). Radiation.
Mechanisms of hemolysis
Two ways: Intravascular or Extravascular (outside of blood vessels). Extravascular = macrophage (usu. cords of Billroth in Spleen) kills IgG, C3b, out-of-shape, Howell-Jolley [tries to take it out and often kill the cell]. Autoimmune (IgG, C3b), Sickle cell disease. End product of phagocytosed RBC = unconjugated bilirubin –> lipid-soluble unconjugatrd bilirubin and binds to albumin and goes to the liver. Therefore, extravascular hemolytic anemias have jaundice. NONE of that bill gets into the urine (b/c albumin and lipid-soluble)
Intravascular hemolysis
Die within the vessel. Congenital bicuspid valve. IgM-mediated on surface of RBC -> all the way to C9 = MAC = hole. Releases hemoglobin. Haptoglobin is the Hb binder = complex that is phagocytosed by macrophage in order to retrieve the hemoglobin and don’t lose it. Haptoglobin decreases. Usually don’t get jaundice. Hemoglobunuria + Haptoglobin low.
Intrinsic vs. Extrinsic Hemolytics Anemia
Intrinsic = something wrong with RBC (spectrin, decay-accelerating factor to neutralize complement, sickle cell, G6PD, PNH); Extrinsic = nothing wrong with RBC (microangiopathic/macroangiopathic anemias; autoimmune hemolytic anemia)
Intrinsic hemolytic anemia
Reticulocyte count > 3%. MAD = Membrane-defect (spherocytosis, PNH), Abnormal Hgb (Sickle cell trait/disease), Deficient enzyme (G6PD def.)
Hereditary Spherocytosis
Removed extravascularly = jaundice (unconjugated). Spectrin. AD. Splenomegaly. Gall bladder disease 2/2 to Ca bilirubinate (pigment?) stones. Dx = osmotic fragility test. Tx = splenectomy
Paroxysmal Nocturnal Hemoglobinuria
Defect in DAF (Decay-accelerating factor). During sleep, mild resp. acidosis -> predisposes to complement attaching to cells (platelets, RBCs, WBCs). DAF -> inc. degradation of complement. Intravascular hemolysis. Morning urine red. Pancytopenia.
Sickle cell disease
AR. Sickle cells on smear. Trait will only have sickle cells in renal medulla and peritubular capillaries. 60%+ HbS in RBC —> sickling. Lowered O2 tension can induce sickling. Hemolytic anemia (extravascular) + occlusion of small blood vessels by sickled cells (vaso-occlusive crisis). Damaged organs over time (nonfunctional by age 2 [Howell-Jolley Body, Strep. pneumo sepsis] and autosplenectomy by 2nd decade). But can’t give Pneumovax till age 2. Newborns have HbF 70% and can inhibit sickling. By 6-9 mo, 1st crisis. Dactilytis. BONE infarction. Susceptible to osteomyelitis by SALMONELLA. Spleen. Hydroxyurea inc. HbF synthesis.
G6PD Deficiency
X-linked recessive (other enzyme X-linked = Lesch-Nyhan). G6P is used to make glutathione, ribose, glycogen. RBC’s don’t have catalase so rely on glutathione to get rid of peroxides. HEINZ bodies (hgb clumped up). Damages membranes -> mostly intravascular hemolysis. Precipitated by infections, drugs (primaquine, dapsone [leprosy]), fava beans. Black, mediterranean. BITE cells. Dx = Don’t use enzyme assays during hemolysis b/c only get bad enzyme. Confirm with a G6PD assay AFTER hemolytic episode.
Autoimmune hemolytic anemias
Warm = IgG. Cold = IgM. Most common is WARM and is SLE. IgG and C3b on surface of RBCs -> extravascular hemolytic anemia. Coomb’s Test (Direct, IgG, C3b for RBC) is POS. (Indirect Coomb’s is often used to screen pregnant women for ab’s).
Three types of drug-induced hemolytic anemia
Penicillin: BPO group attaches to red blood cell. IgG antibody develops against group (HS type II). Methyl-dopa (anti-HTN for pregnant women [hydralazine - drug-induced lupus and methyldopa]): alters Rh antigens -> autoAb’s against own Rh antigens. Immune-complex: Quinidine is classic. Acts as a haptan and a IgM attaches to drug = Immune-complex. (HS-3). Intravascular hemolysis via MAC -> hemoglobinuria and decreased Haptoglobin.
Microangiopathic hemolytic anemia
Schistocytes. AS is most common cause. Intravascular - low haptoglobin. Hemoglobinuria. Could also get Fe-deficiency anemia. Other causes = DIC, TTP, HUS 2/2 PLT plug damages, runner’s anemia, malaria. Falciparum (ring forms, multiple, any time fever)
Benign changes on cells
Leukomoid reaction: looks like leukemia but is benign. 2/2 TB, sepsis. >50k cells in the blood. Over-exagerrated response to infection = kids. Pertussis has WBC > 60k (scary b/c ?ALL).
Atypical lymphocyte
Large bluish cells. CMV, EBV, toxoplasmosis, any hepatitis, phenytoin. EBV infects B cell at CD21. [6-8 week contact sports. splenic rupture]