Haematology Flashcards
What is anaemia
Insufficient oxygen carrying
capacity is due to reduced haemoglobin concentration as seen with insufficient RBC
Haemoglobin concentration below the accepted normal range. The normal range for haemoglobin is affected by sex, age, ethnic group and altitude.
The clinical features of anaemia are largely caused by compensatory measures mobilised to counteract hypoxia. Anaemia can be classified according to red cell morphology or aetiology. Red cell indices and morphology correlate with the underlying cause of anaemia. Wherever possible the cause of anaemia should be determined before treatment is started. Blood transfusion is only required in a minority of cases.
Describe iron deficiency anaemia
Iron is a constituent of haemoglobin and is essential for erythropoiesis.
Iron deficiency is most often caused by long-term blood loss.
Iron deficiency causes a hypochromic microcytic anaemia.
The anaemia is usually easily corrected with oral iron supplements.
It is important to establish the cause of iron deficiency-it may be the presenting feature of Gastrointestinal malignancy.
What is Hb
Iron containing oxygen transport metalloprotein
Within RBCs
Reduction in haemoglobin = anaemia
(reduction in oxygen carrying capacity)
What do maturation of RBC require
Vitamin B12 & folic acid; DNA synthesis
Iron; Haemoglobin synthesis
Vitamins
Cytokines (erythropoeitin)
Healthy bone marrow environment
What can cause anaemia
Failure of Production: hypoproliferation
Reticulocytopenic
Ineffective Erythropoiesis
Decreased Survival
Blood loss, haemolysis, reticulocytosis
Microcytic
-low Hb levels
Iron deficiency (heme deficiency)
Thalassaemia (globin deficiency)
Anaemia of chronic disease
Reticulocyte count then adds further clue as to failure of production or increased losses
Normocytic anaemia
Anaemia chronic disease Aplastic anaemia Chronic renal failure Bone marrow infiltration Sickle cell disease Reticulocyte count then adds further clue as to failure of production or increased losses
Macrocytic anaemia
B12 deficiency, folate deficiency
Myelodysplasia, alcohol induced, drug induced, liver disease, myxoedema.
Reticulocyte count then adds further clue as to failure of production or increased losses
What is nutritional anaemia
Reticulocyte count then adds further clue as to failure of production or increased losses
Reticulocyte count then adds further clue as to failure of production or increased losses
Iron
Essential for O2 transport
Most abundant trace element in body.
Daily requirement for iron for erythropoeisis varies depending on gender and physiolgical needs.
Iron is an essential component of cytochromes, oxygen-binding molecules (i.e., haemoglobin and myoglobin), and many enzymes.
Dietary iron is absorbed predominantly in the duodenum.
Fe+++ ions circulate bound to plasma transferrin and accumulate within cells in the form of ferritin. Stored iron can be mobilized for reuse.
Adult men normally have 35 to 45 mg of iron per kilogram of body weight. Premenopausal women have lower iron stores as a result of their recurrent blood loss through menstruation.
More than two thirds of the body’s iron content is incorporated into haemoglobin in developing erythroid precursors and mature red cells.
Most of the remaining body iron is found in hepatocytes and reticuloendothelial macrophages, which serve as storage deposits.
Reticuloendothelial macrophages ingest senescent red cells, catabolise haemoglobin to scavenge iron, and load the iron onto transferrin for reuse.
Iron metabolism is unusual in that it is controlled by absorption rather than excretion. Iron is only lost through blood loss or loss of cells as they slough.
Men and nonmenstruating women lose about 1 mg of iron per day. Menstruating women lose from 0.6 to 2.5 percent more per day.
An average 60-kg woman might lose an extra 10 mg of iron per menstruation cycle, but the loss could be more than 42 mg per cycle depending on how heavily she menstruates.
Daily dietary requirements
Daily dietary iron requirements differ at various stages of development, between men and women, and between pregnant and nonpregnant women.
The data reported in this table assume an average dietary iron absorption of 10%.
Foods that are rich in iron include:
• Meats: Liver, Liverwurst, Beef, Lamb, Ham, Turkey, Chicken, Veal, Pork, Dried beef
• Seafood: Shrimp, Dried cod, Mackerel, Sardines, Oysters, Haddock, Clams, Scallops, Tuna
• Vegetables: Spinach, Beet greens, Dandelion greens, Sweet potatoes, Peas, Broccoli, String beans,Collards, Kale, Chard
• Breads & Cereals: White bread (enriched), Whole wheat bread, Enriched macaroni, Wheat products, Bran cereals, Corn meal, Oat cereal, Cream of Wheat, Rye bread, Enriched rice
• Fruits: Prunes, Watermelon, Dried apricots, Dried peaches, Strawberries, Prune juice, Raisins, Dates, Figs
• Other Foods: Eggs, Dried peas, Dried beans, Instant breakfast, Corn syrup, Maple Syrup, Lentils, Molasses
Iron metabolism
> 1 stable form of iron:
Ferric states (3+) and Ferrous states (2+)
Most iron is in body as circulating Hb
Hb: 4 haem groups, 4 globin chains able to bind 4 O2
Remainder as storage and transport proteins
ferritin and haemosiderin
Found in cells of liver, spleen and bone marrow
Iron absorption
Regulated by GI mucosal cells and hepcidin
Duodenum & proximal jejunum
Via ferroportin receptors on enterocytes
Transferred into plasma and binds to transferrin
Amount absorbed depends on type ingested
Heme, ferrous (red meat, > than non-heme, ferric forms Heme iron makes up 10-20% of dietary iron
Other foods, GI acidity, state of iron storage levels and bone marrow activity affect absorption
Iron Regulation: Hepcidin
“ the iron-regulatory hormone hepcidin and its receptor and iron channel ferroportin control the dietary absorption, storage, and tissue distribution of iron…
Hepcidin causes ferroportin internalization and degradation, thereby decreasing iron transfer into blood plasma from the duodenum, from macrophages involved in recycling senescent erythrocytes, and from iron-storing hepatocytes.
Hepcidin is feedback regulated by iron concentrations in plasma and the liver and by erythropoietic demand for iron.
Iron transport and storage
Iron transported from enterocytes and then either into plasma or if excess iron stored as ferritin
In plasma: attaches to transferrin
and then transported to bone marrow binds to transferrin receptors on RBC precursors
A state of iron deficiency will see reduced ferritin stores and then increased transferrin
Describe laboratory iron studies
Serum Fe-> hugely variable during the day
Ferritin->primary storage protein and providing reserve, water soluble.
Transferrin saturation->ratio of serum iron and total iron binding capacity-revealing % age of transferrin binding sites tat have been occupied by iron.
Describe transferrin
Made by liver, production inversely proportional to Fe stores. Vital for Fe transport.
Describe total iron binding capacity
Measurement of the capacity of transferrin to bind to iron. It is an indirect measurement of transferrin.
What are the laboratory results in deficiency anaemia
Ferritin-low
Saturation-low
TIBC-high
Serum iron-low/normal
Iron deficiency causes
NOT ENOUGH IN Poor Diet Malabsorption Increased physiological needs LOSING TOO MUCH Blood loss menstruation, GI tract loss, paraistes
Iron deficiency investigations
FBC: Hb, MCV, MCH, Reticulocyte count
Iron Studies: Ferritin, Transferrin Saturation
Blood film
?BMAT and Iron stores
Describe stages of IDA
Before anaemia develops, iron deficiency occurs in several stages.
Serum ferritin is the most sensitive laboratory indicators of mild iron deficiency. Stainable iron in tissue stores is equally sensitive, but is not performed in clinical practice.
The percentage saturation of transferrin with iron and free erythrocyte protoporphyrin values do not become abnormal until tissue stores are depleted of iron.
A decrease in the haemoglobin concentration occurs when iron is unavailable for haem synthesis.
MCV and MCH do not become abnormal for several months after tissue stores are depleted of iron
Iron deficiency anaemia-prevalence
World’s most common nutritional deficiency
2% in adult men (≤ 69 years old)
4% in adult men ≥ 70 years old*
10% in Caucasian, non-Hispanic women
19% in African-American women
Common cause of referral
Excessive menstrual losses 1st cause in premenopausal
women
Blood loss from the GI tract is the most common cause of IDA in adult men and postmenopausal women.
Iron deficiency is the most common nutritional deficiency as well as the most common cause of anaemia throughout the world and a common cause of referral.
Premenopausal women with excessive menstrual losses are particularly at risk of developing iron deficiency anaemia (IDA).
because of the
Iron deficiency anaemia symptoms and signs
Symptoms
fatigue, lethargy, and dizziness
Signs pallor of mucous membranes, Bounding pulse, systolic flow murmurs, Smooth tongue, koilonychias
B12 and Folate deficiency
Folate necessary for DNA Synthesis:
Adenosine, guanine and thymidine synthesis
Both have very similar laboratory finding and clinical symptoms
Can be found together or as isolated
pathologies
Macrocytic Anaemia
Low Hb and high MCV with normal MCHC
Macrocytic anaemia
Megaloblastic : Low reticulocyte count Vitamin B12/Folic acid deficiency Drug-related (interference with B12/FA metabolism) Nonmegaloblastic Alcoholism ++ Hypothyroidism Liver disease Myelodysplastic syndromes Reticulocytosis (haemolysis)
Megaloblastic vs non megaloblastic anaemia
Megaloblastic changes of blood cells are seen in B12 and Folic Acid deficiency. They are characterized on the peripheral smear by macroovalocytes and hypersegmented neutrophils.
What are the causes of folate deficiency
Increased demand:
- pregnancy/breast feeding
- infancy and growth spurts
- haemolysis and rapid cell turnover, eg Sickle Cell Disease
- Disseminated cancer
- Urinary losses (e.g heart failure)
Decreased intake:
- poor diet
- elderly
- chronic alcohol intake
Decreased absorption
- Medication (folate antagonists)
- Coeliac
- Jejunal resection
- Tropical Sprue
Folate comes from most foods with 60-90% lost in cooking. It is absorbed in the Jejunum and the body has enough stores usually for 3-5 months
What is Vitamin B12
Essential co-factor for methylation in DNA and cell metabolism
Intracellular conversion to 2 active coenzymes necessary for the homeostasis of methylmalonic acid (MMA) and homocysteine
Foods containing vit B12:
Animal sources: Fish, meat, dairy
UK intake recommendations are 1.5mcg/day
EU: 1mcg/day and USA: 2.4mcg/day
average western intake 5-30mcg/day
Body (liver) storage: 1-5mg so many years for deficiency.
Requires the presence of Intrinsic Factor for absoprtion in terminal ileum
IF made in Parietal Cells in stomach
Transcobalamin II and Transcobalamin I transport vitB12 to tissues
What are some of the causes of B12 deficiency
Impaired absorption:
- Pernicious anaemia
- Gastrectomy or ileal resection
- Zollinger-Ellison syndrome
- Parasites
Decreased intake:
- malnutrition
- Vegan diet
Congenital causes:
- intrinsic factor receptor deficiency
- Cobalamin mutation C-G-1 gene
Increased requirements
- Haemolysis
- HIV
- Pregnancy
- Growth spurts
Medication
- Alcohol
- NO
- PPI, H2 antagonists
- Metformin
Haematological consequences of B12 deficiency
MCV: normal or raised –>megaloblastic anaemia, ineffective erythropoiesis
Hb: Normal or low
Reticulocyte count: low
LDH: raised –>intramedullary haemolysis
Blood film: Macrocytes, ovalocytes, hypersegmented neutrophils
BMAT: Hypercellular, megaloblastic, giant metamyelocytes –>unusual to need.
MMA: increased, not standard lab test.
Clinical consequences of B12 deficiency
Brain: cognition, depression, psychosis Neurology: myelopathy, sensory changes, ataxia, spasticity (SACDC) Infertility Cardiac cardiomyopathy Tongue: glossitis, taste impairment Blood: Pancytopenia
What is pernicious anaemia
Autoimmune disorder
Lack of IF
Lack of
B12 absorption
Gastric Parietal cell antibodies
IF antibodies
What are the treatments for iron, folic acid, and B12 deficiency
Treat the underlying cause **
Iron – diet, oral, parenteral iron supplementatin, stopping the bleeding
Folic Acid – oral supplements
B12 – oral vs intramuscular treatment
What is included in a FBC
RED BLOOD CELL RESULTS Hb: concentration of Haemoglobin Hct: Percentage of blood volume as RBC MCV: Average size of RBC MCH: Average haemoglobin content of RBC RDW: Range of deviation around RBC size Reticulocyte count Blood film WHITE BLOOD CELL RESULTS Total WBC and differential Neutrophils, lymphocytes, monocytes, basophils, eosinophils
PLATELET RESULTS
Platelet count and size
OTHERS: WARNING FLAGS
What does a blood film show?
WHITE BLOOD CELL RESULTS
Total WBC and differential
Neutrophils, lymphocytes, monocytes,
basophils, eosinophils
PLATELET RESULTS
Platelet count and size
OTHERS: WARNING FLAGS
Red cells: -size/anisocytosis (big or small) -colour (Hb content) -shape (round, TDP, irregular, elliptocytes-poikylocytosis -Polychromasia -Inclusions White cells: -Numbers (too many/few) -Normal morphology -immature cells (myelocytes, precursors) -Abnormal cells (blasts, atypical lymphoid cells) Inclusions
What are the different colour coded tubes in laboratories and what are they used for?
Red lid=for serum= plain tube, no anticoagulant, so clot forms. Used generally.
Yellow lid=for serum=contains serum separator gel, known as Serum separator tube (SST)
Purple lid=for plasma=contains ethylene diamine tetra acetic acid (EDTA) anticoagulant, for whole blood analysis, red cell analysis and lipids and lipoproteins.
Green lid: lithium heparin anticoagulant, for plasma, general use.
Grey lid: for plasma, contains fluoride oxalate, for glucose, lactate and alcohol.
Blue lid: for serum, contains trace element, for copper and zinc
Heparinised syringe: for arterial blood sampling.
Symptoms of anaemia
Fatigue, weakness, dyspnoea, palpitations, headache, dizziness, tinnitus, and chest pains (due to exacerbation of angina)
Symptoms of leucopenia (particularly neutropenia) //low white cell count
Unusually severe or recurrent infections. It is usually a reduction in neutrophils (neutropenia) which will cause clinical problems. Serious blood diseases such as acute leukaemia can present as life threatening infections or as apparently trivial infections (eg sore throat) which are unusually refractory to normal treatment. Perineal sepsis can be a problem.
Symptoms of thrombocytopenia (low platelet count)
Thrombocytopenia leads to haemorrhagic tendency and common presentations include epistaxes (nose bleeds), bleeding from gums, menorrhagia, and excessive bleeding after trauma or surgery. Patients may also complain of easy bruising or petechial rash.
Symptoms attributable to abnormal coagulation
Patients with a defect in the coagulation cascade (low factor VIII in haemophilia A) bleed easily after surgery and trauma, but the pattern of spontaneous haemorrhage is normally different to that seen in platelet disoders. Excessive bleeding after trauma, spontaneous bleeds into joints and muscles.
symptoms of infiltration by malignancy
Malignant disorders of the blood such as leukaemia, and lumphomas, have the capacity to invade tissues. Lumps, caused by lymphadenopathy, pain, neurological symptoms.
Difference between anaemia and haemolytic anaemia
ANAEMIA = reduced haemoglobin level for the age and gender of the individual
HAEMOLYTIC ANAEMIA = anaemia due to shortened RBC survival
What is haemolysis
Shortened red cell survival 30 - 80 days
–>
Bone marrow compensates with increased red blood cell production
–>
Increased young cells in circulation = Reticulocytosis +/- nucleated RBC
–>
Compensated haemolysis: RBC production able to compensate for decreased RBC life span = normal Hb
Incompletely compensated haemolysis: RBC production
What are the clinical findings of haemolysis
Jaundice
Pallor/fatigue
Splenomegaly
Dark urine
Haemolytic crises-increased anaemia and jaundice with infections/ precipitants
Aplastic crises-anaemia, reticulocytopenia with parvovirus infection
Chronic clinical findings include:
Gallstones - pigment
Leg ulcers (NO scavenging)
Folate deficiency (increased use)
What are the haemolytic anaemia laboratory finings
Increased reticulocyte count Increased unconjugated bilirubin Increased LDH (lactate dehydrogenase) Low serum haptoglobin protein that binds free haemoglobin Increased urobilinogen Increased urinary haemosiderin Abnormal blood film
How do we classify haemolytic anaemias
- Inherited Hereditary spherocytosis
- Acquired Paroxysmal nocturnal haemoglobinuria
Site of RBC destruction - Intravascular Thrombotic thrombocytopenic purpura
- Extravascular Autoimmune haemolysis
Origin of RBC damage - Intrinsic G6PD deficiency
- Extrinsic Delayed haemolytic transfusion reaction
What is hereditary spherocytosis
Common hereditary haemolytic anemia
Inherited in autosomal dominant fashion (75%)
Defects in proteins involved in vertical interactions between the membrane skeleton and the lipid bilayer
Decreased membrane deformability
Bone marrow makes biconcave RBC, but as membrane is lost, the RBC become spherical.
Defects in vertical interaction Spectrin Band 3 Protein 4.2 Ankyrin
What is hereditary elliptocytosis
Defects in horizontal interaction
Protein 4.1
Glycophorin C
(Spectrin – HPP)
Clinical features of hereditary spherocytosis
Asymptomatic to severe haemolysis
Neonatal jaundice
Jaundice, splenomegaly, pigment gallstones
Reduced eosin-5-maleimide (EMA) binding – binds to band 3
Positive family history
Negative direct antibody test
What happens if you have glucose 6 phosphate deficiency
Role of the HMP shunt:
Generates reduced glutathione
Protects the cell from oxidative stress
Effects of oxidative stress:
Oxidation of Hb by oxidant radicals
Resulting denatured Hb aggregates & forms Heinz bodies – bind to membrane
Oxidised membrane proteins – reduced RBC deformability.
Hereditary, X-linked disorder
Common in African, Asian, Mediterranean and Middle Eastern populations
Mild in African (type A), more severe in Mediterraneans (type B)
Clinical features range from asymptomatic to acute episodes to chronic haemolysis
Features: Haemolysis Film: Bite cells Blister cells & ghost cells Heinz bodies (methylene blue) Reduced G6PD activity on enzyme assay May be falsely normal if reticulocytosis
Describe pyruvate kinase deficiency
PK required to generate ATP Essential for membrane cation pumps (deformability) Autosomal recessive Chronic anaemia Mild to transfusion dependent Improves with splenectomy
What is thalassaemias
-describe also the diagnosis of thalassaemia traits
Imbalanced alpha and beta chain production
Excess unpaired globin chains are unstable
precipitate and damage RBC and their precursors
Ineffective erythropoiesis in bone marrow
Haemolytic anaemia
Diagnosis of thalassaemia trait:
Asymptomatic
Microcytic hypochromic anaemia
Low Hb, MCV, MCH
Increased RBC
Often confused with Fe deficiency
HbA2 increased in b-thal trait –(diagnostic)
a-thal trait often by exclusion
globin chain synthesis (rarely done now)
DNA studies (expensive)
What is beta thalassaemia major
Transfusion dependent in 1st year of life
If not transfused:
Failure to thrive
Progressive hepatosplenomegaly
Bone marrow expansion – skeletal abnormalities
Death in 1st 5 years of life from anaemia
Side effects of transfusion:
Iron overload
Endocrinopathies
Heart failure
Liver cirrhosis
Features of SCD
Clinical: Painful crises Aplastic crises Infections Acute sickling: Chest syndrome Splenic sequestration Stroke Chronic sickling effects: Renal failure Avascular necrosis bone
Laboratory: Anaemia Hb often 65-85 Reticulocytosis Increased NRBC Raised bilirubin Low creatinine
Describe immune haemolysis
Autoimmune: Idiopathic Usually warm IgG, IgM Drug-mediated Cancer associated LPDs
Alloimmune: Transplacental transfer: Haemolytic disease of the newborn: D, c, L ABO incompatability Transfusion related Acute haemolytic transfusion reaction ABO Delayed haemolytic transfusion reaction E.g Rh groups, Duffy
Describe non-immune acquired haemolysis
Paroxysmal nocturnal haemoglobinuria Fragmentation haemolysis: Mechanical Microangiopathic haemolysis Disseminated intravascular coagulation Thrombotic thrombocytopenic purpura Other: Severe burns Some infections: e.g. malaria
What is hereditary spherocytosis and hereditary elliptocytosis an example of?
Inherited red cell membrane disorder of haemolytic anaemias. They are caused by a deficiency in red cell membrane.
