RBC Flashcards
4 causes of Heinz bodies
G6PD Deficiency
NADPH Deficiency
Oxidant drug-induced
Unstable hemoglobin variants
Thalassemia
Chronic liver disease
Hyposplenia/asplenia
Chemical induced
See on Supravital staining
Denatured hemoglobin
Pathophys of G6PD deficiency
G6PD normally restores NADPH levels which maintains levels of reduced glutathione in RBCs. Glutathione protects RBCs from oxidative damage. In G6PD deficiency, glutathione levels are depleted and so RBC are vulnerable to oxidizing agents.
Hexo-monophosphate pathway (PK is glycolytic pathway)
Reasons to initiate transfusions in a child with thalssemia
- Symptomatic anemia- fatigue, cardiopulmonary compromise, pHTN
- Delayed growth/no sexual characteristics
- Extramedullary hematopoiesis (cord compression, pathologic #, bone pain from tumor, symptomatic splenomegaly)
- Frequent hemolytic crises
- Thrombosis/stroke
Others:
leg ulcers
Poor school peformance/QoL
Name 4 causes of pure red cell aplasia
· Parvovirus B19 (virus binds to blood group p antigen)
· Thymoma
· Lymphoproliferative disorder (esp. LGL, CLL, MM)
· MDS
Solid tumors, breast, lung renal
· Autoimmune (hypothyroidism)
· Transient erythroblastopenia of childhood
· Drugs (rhEPO, post myeloablative chemotherapy eg busulphan, melphalan)
Meds that are contraindicated in G6PD deficiency; Inheritance pattern.
X-linked
Sulfamethoxazole-Trimethoprim.
Dapsone
Urate oxidase-rasburicase
Methylene blue
Nitrofurantoin
Ciprofloxacin
3 causes of a dual population on blood film in an anemic patient
Recently transfused microcytic/macrocytic anemic patient
Treated Iron Deficiency Anemia or any nutritional deficiency
Erythropoietin Therapy → reticulocytosis
MDS/RARS
Hemolytic processes involving a reticulocyte response
Mixed nutritional deficiency
Name 3 positive results of treating patients with SCD with HU
Reduced frequency of pain episodes
Reduced frequency of ACS
Reduced transfusions in adults with Hb SS
Increases HbF levels
Reduced mortality without an increased risk of malignancy
Chains that make up the following hemoglobins: Gower 1, Gower2, Portland, HgF, Hg A, HgA2.
Hb Gower 1 zeta2 epsilon2
Hb Portland zeta2 gamma2
Hb Gower 2 alpha2 epsilon2
Hb F alpha2 gamma2
Hb A alpha2 beta2
Hb A2 alpha2 delta2
Next to each of the following, write whether the patient has “a comparable” phenotype to HbSS by writing “sickler” or “non-sickler”.
Hb SC:
Hb beta0thal/S:
Hb SD:
Hb beta+thal/S:
Hb SLepore:
HbS-HPFH:
Hb SC: Sickler
Hb beta0thal/S: Sickler
Hb SD (Punjab): Sickler
Hb beta+thal/S: Sickler
Hb SLepore: Sickler
HbS-HPFH: No (if homo HPFH will not sickling, but if heter will sickling)
HbSO(arab) = sickler
HbES =Sickler (HgEbeta thal does hemolyze)
Name 2 hemolytic disorders associated with enzyme deficiencies. Describe the morphological changes for each
G6PD Deficiency: Heinz Bodies, bite cells, blister cells
PK Deficiency: Echinocytes, reticulocytosis (esp. after splenectomy), nRBCs, anisopoikilocytosis
Pathophys of PK deficiency.
Abnormality of glycolytic pathway (Embden-Meyerhof pathway) –> leads to decrease in ATP–>The lack of ATP disturbs the cation gradient across the erythrocytic cell membrane, causing the loss of potassium and water, which results in cell dehydration, contraction, and crenation (echinocytes) and leads to premature destruction of the erythrocyte. –> decreased deformability and hemolysis
Smear: (echinocytes or “prickle cells”), reticulocytosis (esp. after splenectomy), nRBCs, anisopoikilocytosis
AR, gene is PKLR gene
*high level of 2,3-diphosphoglycerate (2,3-DPG) increases the patient’s exercise tolerance by causing a rightward shift in the hemoglobin-oxygen dissociation curve.
Name 4 ways to decrease the complications of IV iron administration.
Provide test dose prior to full dose administration
Pretreatment with steroids
Slow infusion
Avoid high molecular weight dextran
Lower doses of Iron vs Dilution
Tylenol following administration
Avoid in patients with hx of rxn to IV Fe or severe allergy/asthma
Consider avoiding in setting of active infection.
Name 4 causes of refractory iron deficiency anemia
Active H. Pylori
Celiac Disease:
Autoimmune gastritis
Hereditary Iron-refractory iron deficiency anemia (IRIDA) = AR due to TMPRSS6 gene mutation (causes high hepcidin)
Ongoing bleeding
Non compliant
Inadequate iron dose
Mechanism and treatment for post-renal Tx polycythemia.
MOA- ?RAS dysregulation occurs @ 8-24 months post renal Tx. (Hg >170 or hct >51 x 6 mos)
Hormones involved in pathogenesis: RAS, EPO, IGF-1, androgens
Treatment
1. ACEi/ARB
2. Phlebotomy if >180 ( if >180 (or Hct>0.55), target 0.5.. unlike PV 0.45)
3. Native kidney nephrectomy (if elevated EPO)
Causes for high hepcidin
hepcidin HIGH → BLOCKS ferriportin = less iron in circulation
- Increased iron stores (non-pathological)
- inflammation/infection (TNFa , IL6)
- IRIDA due to TMPRSS6 mutation
- Iron replacement (transfusions, PO, IV)
- CKD
Causes for low hepcidin
hepcidin LOW → OPENS ferriportin =more iron in circulation
- Fe deficiency
- Hereditary hemochromatosis
- Increased erythroferrone - will be increased in any state of ineffective erythropoiesis ie Thalassemia
- ESA’s
- Liver disease
- Etoh
- HCV
- Estrogen and Testosterone
“sex, drugs and rock and roll (Iron Maiden)”
Non HFE gene mutations in HH
- hemojuvelin (low hepcidin)
2.hepcidin (loss of function)
3.ferroportin (classical: unable to export iron from macrophages, nonclassical: unable to bind hepcidin) - transferrin receptor (low hepcidin)
HFE (H63D, C282Y, S65C)
What are four proteins in the RBC membrane?
What are three disorders associated with cytoskeletal RBC defects?
- Ankyrin
- Band 3
- Alpha-spectrin
- Beta spectrin
- Protein 4.2
- Protein 4.1.
- Glyocophorin C
HE, HS, HPP, Southeast Asian Ovalocytosis
Causes of microcytosis aside from iron deficiency and hemoglobinopathy?
- LEAD poisioning
- Inherited sideroblastic anemia
- Cu deficiency
4 Zn excess
5.Anemia of chronic inflammation
6 Acquired sideroblastic disorder
-EtOH
-Lead poisoning
-Zn excess
-Cu def
-Drugs: INH, linezolid, chloramphenicol, cycloserine
Pearson syndrome - MDS with acquired thalassemia
- Pediatric Hereditary Elliptocytosis –> 2ry to fragments
What condition produces a “Hg F” only pattern on newborn screening?
Beta thal major!
Child with abrupt normocytic anemia, reticulocytopenia, N H & P and then spontaneous recovery with brisk reticulocytosis. What is the diagnosis?
Transient erythroblastopenia of childhood.
IgG Ab against erythroblasts.
Consequences of iron def in pregnancy?
- postpartum depression
- poor maternal-infant behavioral interaction
- impaired lactation
- low birth weight
- premature delivery
- intrauterine growth retardation
- increased fetal and neonatal mortality.
Recommended daily dose of elemental iron in pregnancy
30mg
(can give concurrently with Vitamin C to increase absorption)
Consider IV iron only after week 13
What is the generic name for monofer? Why is iron absorption increased?
- Ferric carboxymaltose, one-time infusion of 1,000 mg
2.Greater binding of the carbohydrate moiety to iron
What TSat should prompt screening for HH in women and men? What is the most commonly identified HFE gene mutation and which ethnicity is this seen most commonly in?
First repeat fasting! Then if still elevated:
- 0.50 men, 0.45 women
- C282Y (60-90%)
- Northern European, mainly male
What symptoms of HH will not improve with phlebotomy?
Arthralgias**, diabetes, and hypogonadism may not resolve, and cirrhosis or risk for hepatocellular carcinoma may not be reversed.
Fatigue, elevated liver enzymes and skin bronzing WILL improve.
Initiate phleb if ferritin >300 males, >200 females
How does juvenile hemochromatosis typically present?
- life-threatening heart failure
2.hypogonadotropic hypogonadism - impaired glucose tolerance or diabetes mellitus
(liver involvement rare, inheritance= AR)
Juvenile = more heart overload
Juvenile HH genes: hemojuvelin, hepcidin?
Two disadvantage of Deferiprone (Ferriprox)?
Disadvantage- can cause agranulocytosis, thrice daily dosing
What is the role of erthroferrone?
a protein hormone produced by erythroblasts, inhibits the action of hepcidin and thereby increases the amount of iron available for hemoglobin synthesis in times of stress erythropoiesis.
Encoded by the ERFE gene
What are 4 reasons that breastfeeding and/or cow’s milk diet in infants leads to IDA?
- Poor iron content in cows milk + breast milk
- Not eating other iron rich food (milk only diet)
- Occult GI blood loss from cow’s protein enteropathy
- Impaired absorption secondary to calcium + milk proteins in milk
How does soluble transferrin receptor (sTFr) help differentiate IDA from ACD?
Circulating protein derived from cleavage of the membrane transferrin receptor on erythroid precursor cells within the marrow. Combined with ferritin into sTfR-ferritin index.
In IDA, sTfR-ferritin index—> elevated (> 2) due to increased erythropoietic drive and low iron stores.
Low in ACD.
Ratio increased in IDA because high sTrR and low ferritin
Decreased in ACD because low erythropioetic drive so low sTrR but high ferritin
3 reasons for anemia in ESRD?
- Decreased EPO production 2nry to less renal cortical cells
- impaired RBC deformability and membrane permeability secondary to uremia and secondary hyperparathyroidism
- hemodialysis induced hemolysis
- Increased iron demand and utilization related to ESA therapy also contributes to anemia of CKD.
Serum folate levels are diurnal and fluctuate making the test not reliable. RBC folate can be measured instead, however may be affected by…
concurrent vitamin B12 deficiency… in which the RBC folate will be low.
Treatment of X-linked congenital sideroblastic anemia and alcohol induced sideroblastic anemia.
Vitamin B6 (Pyridoxine)
Describe the vertical protein interactions in RBC. These are disrupted in what disorder?
- Vertical interactions= perpendicular to the plane of the membrane
- spectrin-ankyrin–band 3 association facilitated by protein 4.2 and attachment of spectrin- actin–protein 4.1 junctional complexes to glycophorin C
- Disrupted in HS
Describe the Horizontal protein interactions in RBC. These are disrupted in what disorder?
- parallel to and underlying the plane of the membrane
- involve the assembly of α- and β-spectrin chains into heterodimers, which self-associate to form tetramers
- Disrupted in HE/HPP (spectrin-spectrin, spectrin-protein 4.1)
Most common mutations that lead to hereditary spherocytosis?
Most common–>least common
1. defect of the ankyrin molecule
2. both ankyrin and spectrin deficiency
3. spectrin only
4. band 3 mutations
Rare: β-spectrin, α-spectrin, protein 4.2
8 clinical manifestations of HS
- Pigmented gallstones
- Splenomegaly
- Iron overload (even w/o Tx)
- Aplastic crises
- Hyperhemolysis
- Extramedullary hematopoesis–> maxillary hyperplasia, masses
- Folic deficiency
- Leg ulcers
- Jaundice
- Symptomatic anemia
What are the 3 sub-types of HE?
- Common HE or more severe HPP (MCV 50-60, but hemolysis usually mild and does not need Tx)
- spherocytic HE, a phenotypic hybrid between HE and HS
- Southeast Asian ovalocytosis (heterozygous band 3 mutation, asymptomatic)
*HE is AD, HPP mostly AR
What is dehydrated hereditary stomatocytosis, why is this important to rule out in a patient with suspected HS?
- perinatal edema and/or pseudohyperkalemia
due to mutations in the PIEZO1 gene - Splenectomy is contraindicated due to increased thrombosis risk!
What test can you do to distinguish HS from hereditary stomatocytosis?
Osmotic gradient ektacytometry–> measures deformability of whole RBCs as a function of osmolality.
EMA is usually normal in stomatocytosis and HE. Decreased in HPP.
Can also look at morphology, macrocytic anemia.
Normal metabolism of the mature RBC involves which 2 principal pathways of glucose catabolism…
- Glycolytic pathway
- Hexose-monophosphate shunt
What is one cause of falsely normal (negative) PK levels?
Post-splenectomy!
Reticulocytes have high levels of PK—> post spelenectomy leads to dramatic reticulocytosis—> normal or borderline low PK level.
If in doubt, measure G6PD and hexokinase. A disproportionately “normal” PK level suggests PK def.
G6PD A- variant has a more modest phenotype with hemolysis only observed after exposure to an oxidant drug, why is this?
an adequate reticulocyte response can result in restoration of the hemoglobin concentration even if the offending drug is continued because the newly formed reticulocytes are relatively resistant to oxidant stress given their higher G6PD levels.
Therefore, never test for G6PD after a hemolytic crises as may get a false negative due to increased retics or transfusion.
5 reasons for an elevated ferritin/Tsat other than HH?
- Iron overload from chronic transfusions (sickle, leukemia, aplastic, AA etc.)
- Thalassemia
- HLH
- Hereditary sideroblastic anemia
- Chronic hemin infusions (porphyria)
- Adult onset Still’s disease
- Benign hyperferritinemia
- Hereditary aceruloplasminemia (mimics HH)
What are the 3 factors that predict adverse transplantation outcomes in Beta-thal major patients?
- Hepatomegaly (>2cm below costal margin)
- Hepatic fibrosis
- Irregular iron chelation (started >18 mos after first transfusion and deferoxamine <5days/wk)
Class 1=0 factors
Class 2= 1 or 2 factors
Class 3= 3 factors
7 chelator side effects:
- High frequency hearing loss
- Retinopathy
- Nephrotoxicity
- Hepatoxicity (Increased ALT)
- GI side effects (nausea/diarrhea) in oral formulations
- Agranulocytosis (Deferiprone)
- Iron-related Yersinia/Vibrio vulnificus as chelators transfers iron to bacteria (Desferoxamine)
Eyes+ears, kidneys+liver, GI, neuts, infections
2 causes of elevated ferritin with N Tsat.
Classical Ferroportin disease (Type 4A)
Hereditary aceruloplasminemia (mimics HH)
List 10 long-term symptoms or consequences of beta thalassemia major other than iron overload.
- Jaundice
- Pigmented gallstones
- HSM
- Symptomatic anemia, including consequences of long-term transfusion (alloimmunization, Tx Rxn, iron overload)
- Skeletal abnormalities (masses, frontal bossing, pain)
- Growth delay
- Osteoporosis
- Dilated cardiomyopathy from anemia
- Leg ulcers
- Thrombosis
- Pulmonary HTN (restrictive pattern on PFTS, mechanism unknown)
- Increased risk of secondary malignancy.
5 long-term consequences of iron overload
- Hypothyroidism
- Hypogonadism (delayed puberty)
- Diabetes
- Restrictive cardiomyopathy
- Cirrhosis
- Increased risk of viral hepatitis
4 non-hematologic conditions with inappropriately high EPO level and increase RBC?
- Hepatocellular carcinoma
- Uterine leiomyeoma
- Post renal cadaveric transplant
- Cerebellar hemangioblastoma
- Pheochromocytoma
- RCC
What are the 2 forms of hemoglobin H disease? What the the common ethnic groups associated with each type?
- “deletional” (ie, –/a-)–>asian/african
- “nondeletional: (ie, –/aat), in which the “t” stands for a mutant alpha chain such as Hb constant spring (HbCS)–>Mediterranean (tend to be more severe)
What is the clinical phenotype of hemoglobin H disease?
- Quite variable (asymptomatic to hydrops)
- Usually anemia Hg 90-110g/l, MCV 62-77. May require transfusion support in pregnancy, infxn (aplastic crises) or with exposure to oxidative drugs.
- May have ineffective/extramedullary erythropoiesis, iron overload, HSM
3 complications of splenectomy?
- Encapsulated organisms
- Arterial and venous thrombosis
- Pulmonary hypertension
Name 6 beta chain mutations that can pair with sickle cell disease.
- Beta thal +
- Beta thal 0
- Hemoglobin C
- Hemoglobin E
- Hemoglobin D
- Hemoglobin O-arab
- HPFH
Sickle cell disease is caused by what AA substitution?
abnormal sickle cell hemoglobin protein (HbS) β-globin chain revealed a mutation where glutamic acid is replaced with a valine (β6Glu→Val).
How much hemoglobin S, F, A2, and A do you make in hg SC?
In SC:
S:50%
F:<5%
A2:0%
A:0%
C:50%
Hemoglobin in 10-15% with mild microcytosis.
What is Crizanlizumab? What is the land mark trial? SE?
Monoclonal Ab that binds P-selectin which affects sickled RBC rolling/adhesion to the endothelium.
IV q4weeks
SUSTAIN TRIAL
- Reduced number of crises
– Improved prop with no crisis in the year (45%)
– Trend toward fewer hospital days
SE: Arthralgas, diarrhea, CP
L-glutamine MOA? Trial? SE?
Anti-oxidant that increases the proportion of reduced NAD in RBCs ie. oxidative stress on RBC.
Powder BID
No trial name:
– Fewer crises than placebo (3.0 vs 4.0)
– Fewer hospitalizations (2.0 vs 3.0)
SE: MSK pain, CP, nausea, fatigue
MOA Voxelotor? Trial? SE?
Stabilizes the OXYgenated Hg state, to prevent HbS polymerization
PO daily
Meant to increase Hg and decrease hemolysis
HOPE trial:
• Phase 3, double blind, randomized, placebo controlled trial.
• Higher percentage of individuals with a Hb response in voxelotor 1500 mg group (51%)
compared to placebo (7%).
SE: nil between 2 groups
What is a feature seen in Hg SC disease that is not as commonly seen in Hg SS disease?
50 percent lower rate of acute painful episodes
higher incidence of proliferative retinopathy
Osteonecrosis also common in both
C co‐migrates with E & A2 (CEA2) need acidic gel, crystals on smear
Indications for initiation of HU in SCD
-painful VOC >3x/yr
-chronic pain interfering with daily activities
-ACS
-severe chronic anemia interfering with daily activities
-for all infant >9 mon, children and adolescents to decrease complications
-weak recommendation for chronic kidney disease on EPO to improve anemia
. Treatment-induced alloantibodies (inhibitors) are much less frequent in severe hemophilia B (factor IX deficiency) than in severe hemophilia A (factor VIII deficiency). What are TWO possible explanations for this difference?
- Factor IX deficiency more due to missense mutations therefore their protein is more similar to the normal Factor IX, unlike FVIII which is more due to deletions/nonsense mutations.
- Factor VIII is a larger protein; highly mutatable protein (1/3 spontaneous case in hemophilia A; cannot rely on family history) and more immunogenic.
