Anemia Flashcards
What is anemia? What does it result in?
Decrease in the number of red blood cells or less than normal quantity of hemoglobin (Hgb) in the blood
Results in decreased oxygen carrying capacity in the blood
Anemia is…..
An objective sign of a disease
Etyiology of Anemia
Several etiologies
What dictates treatment of anemia?
Diagnosis is important to dictate tx
Where are RBC’s formed?
Bone Marrow
Termed erythropoiesis
Adults: spine, ribs, sternum, clavicle, pelvic crest, ends of long bones
Children: most bone marrow space
What do RBC contain? What makes it up?
RBCs contain hemoglobin:
–> protein component (2 alpha/2 beta chains)
–> heme (porphyrin ring + iron)
Is adult hemoglobin the same as a babies?
Two alpha and two gamma chains
Describe the process of Erythropoiesis
How long is the process of erthyropoiesis?
One week long (7 days)
What guides the process of erthropoiesis?
Works on a feedback loop
↓ tissue oxygen concentration signals the kidneys to ↑ production and release of EPO
What is the function of EPO?
stimulates stem cells to differentiate
↑ release of reticulocytes from bone marrow
induces Hb formation
What is the RBC turnover? Where does this occur?
120 Days
Mainly the spleen, some broken down by the bone marrow
Describe the normal cycle of erythropoiesis and turnover
Normally, this system is in balance
EPO matching new erythrocyte production to the natural rate of loss of RBCs
Anemia is a _______ of what?
A symptom of many pathological conditions
Anemia is associated with: (What may cause anemia?)
Nutritional deficiencies
Acute or chronic diseases
Drug induced
How can anemia be classified?
Pathophysiology or by morphology
What are the 3 main pathophysiological causes of anemia?
1) BLOOD LOSS
Trauma, ulcer, hemorrhoids etc. e.g. ASA
2) INADEQUATE RBC PRODUCTION
–> Nutritional deficiency: vitamin B12, folic acid iron
–> Erythroblast deficiency: bone marrow failure (aplastic anemia, irradiation, chemotherapy) or bone marrow infiltration (tumors, cancers)
–> Endocrine deficiencies
–> Chronic disease: ex renal, liver, infection
3) EXCESSIVE RBC DESTRUCTION
Autoimmune, drug, infection
How can anemia be classified by morphology?
Size
Microcytic
Normocytic
Macrocytic (to big)
–> megaloblastic
–> non-megaloblastic
Colour
Hypochromic (pale)
Normochromic
Hyperchromic (darker than normal)
How is the size of an RBC determined?
Size is reflected by the mean corpuscular volume (MCV)
Describe the specific sizes of RBC?
Microcytic: <80 fL (“small”)
Normocytic: 80-100 fL (“normal”)
Macrocytic: >100 fL (“big”)
How is the colour of an RBC determined?
Colour is reflected by the mean corpuscular Hb concentration (MCHC)
Describe the specific colours of RBC’s?
Hypochromic: pale
Normochromic: normally coloured
Hyperchromic: darker
What are the reasons why an anemia may be microcytic?
primarily a result of Hb synthesis failure or Hb insufficiency
can be due to issues with the “heme” portion or the “globin” portion
What are the reasons why an anemia may be normocytic?
anemia with normocytic cells means the RBC are normal-sized but there is a low # of them
↓ production or ↑ destruction or loss
What are the two types of macrocytic anemia? What is the difference?
Megaloblastic
Impaired DNA synthesis
Ex: B12, folate deficiency
Non-megaloblastic
Not caused by impaired DNA synthesis
Ex: liver disease
Megaloblastic anemia is due to…..
Impaired DNA synthesis
Non-megaloblastic anemia is due to……
Not caused by impaired DNA synthesis
Onset of Anemia
May be acute or develop slowly
What causes the signs and symptoms of anemia?
Signs & symptoms vary with degree of RBC reduction & how long it has been present
What is the end result of anemia?
End result is a decrease in the oxygen carrying capacity of the blood
Perfusion to nonvital tissues is compromised to sustain perfusion of vital organs
Initially patients be asymptomatic
What are the common symptoms of anemia?
Fatigue, dizziness, weakness, SOB, tachycardia
↓ mental acuity
Pallor, cold extremities
Diagnosis of anemia includes:
Medical History
Physical Examination
A medical history for the diagnosis of anemia depends on:
Past & current hgb & bloodwork if available
Comorbid conditions
Occupational, environmental & social history (menstrual cycle, alcohol, pregnancy)
Transfusion
Family history
Medications (antiretrovirals, immunosuppressants, cytotoxic, folate antagonists)
A physical examination for the diagnosis of anemia depends on:
Pallor
Postural hypotension, tachycardia (hypovolemia – acute blood loss)
Neurologic findings (B12 deficiency)
Jaundice? (hemolysis)
Bleeding gums, blood in stool, urine, epistaxis etc. (hemorrhage)
A complete blood count encompasses:
Hemoglobin (Hb)
Measures the amount of hemoglobin in the bloo
Hematocrit (Hct) – amount of packed red blood cells (%)
Packed cell volume
RBC count
RBC indices
MCV, MCH, MCHC
What does MCV mean?
MCV=mean corpuscular volume
Average RBC volume
What does MCH mean?
MCH=mean corpuscular hemoglobin
Ave mass of Hb/RBC
What does MCHC mean?
MCHC=mean corpuscular hemoglobin concentration
Average concentration of Hb within a volume of a packed volume of RBC. Shows colour
What is RDW?
RDW=Red blood cell distribution width
Measure in the variation of RBC width
What blood test informs one of RBC colour?
MCHC
Other laboratory evaluations that may be used for diagnosis?
RBC morphology
Reticulocyte count
Iron studies
Ferritin, serum iron, TIBC (total iron-binding capacity)
Peripheral blood smear
Stool for occult blood (G.I. Bleed, Cancer, marker for bleeding)
Bone Marrow aspiration and biopsy
The WHO defines anemia by…..
Anemia: Definition by hemoglobin
Men: <130 g/L
Women: <120 g/L
What are some specific types of anemia?
Deficiency-related anemias
Iron
Vit B12
Folate
Hemolytic anemia
Sickle cell anemia
Anemia related to other diseases/conditions
Anemia of chronic disease, CKD, critical illness/blood loss
Aplastic anemia
What is the most common nutritional deficiency worldwide?
Iron Deficiency
What are the sx of iron deficiency anemia?
Associated with symptoms of pallor, cardiovascular, respiratory and cognitive complications & decreased quality of life
Describe the general process of iron deficiency anemia
A negative state of iron balance in which daily iron intake are unable to meet RBC and other body tissue needs
What are some causes of iron deficiency anemia?
Lack of dietary intake
–> Vegetarians/vegans, poor diet
Blood loss
–> Menstruation, gastrointestinal (e.g. peptic ulcer), trauma
Decreased absorption
–> Celiac disease, medication, gastrectomy, regional enteritis
Increased requirement
–> Infancy, pregnant/lactating women
Impaired Utilization
–> Hereditary, iron use
What acronym can be used to describe the causes of iron deficiency?
Need – increased need as in pregnancy, children during stages of rapid growth, etc.
Intake is low, e.g. in malnutrition
Malabsorption
Blood
Loss, e.g. GI bleeding
Excessive donation, e.g. in blood donors
What is the relationship between iron-deficiency anemia and mortality?
Rarely a direct cause of death
Moderate-severe iron deficiency anemia can cause hypoxia –> aggravate underlying pulmonary/CV disorders
What is the relationship between iron deficiency anemia and morbidity?
Symptoms can be disruptive, impair daily functioning, etc
Slowed growth rate in children, ↓ ability to learn, lower IQ
Splenomegaly may occur with severe, persistent, untreated iron deficiency anemia
What is iron-deficiency anemia associated with in the elderly?
Anemia is associated with:
↑ risk of hospitalization and mortality
↓ quality of life
↓ physical functioning
What is iron-deficiency anemia associated with in the pregnant?
During pregnancy, anemia increases risk for:
low birth weights
preterm delivery
perinatal mortality
May be associated with postpartum depression
Describe the distribution of iron in the body
Body contains ~ 3-5g, of which 2g are found in Hg
Significant amount is stored as ferritin or aggregated ferritin (hemosiderin) in the liver, spleen, bone marrow
Small fraction in plasma, of which most is bound to transferrin (transport protein)
Describe iron stores in the body in comparison to RBC lifespan
Despite constant turnover of rbc, iron stores are usually well preserved
What controls iron metabolism?
Iron metabolism is regulated by hepcidin (hormone produced by liver, promotes storage)
Describe iron absorption in the body
Fe3+ (ferric) iron is ingested in the diet
Ionization in the stomach and reduction to Fe2+
Fe2+ (ferrous) iron is absorbed from the duodenum and upper jejunum by active transport
Fe2+ binds to transferrin (transport protein)
Incorporation into hemoglobin or stored as ferritin
Describe serum iron lab value. What lab value measures it?
Concentration of iron bound to transferrin.
Best interpreted in context with TIBC; fluctuate, subject to individual diurnal variation & may remain in normal range when iron stores are dropping
Describe ferritin lab value. Is it beneficial or detrimental to lab values?
‘Storage iron’
Most sensitive but non-specific and is elevated in inflammatory conditions, liver disorders etc.
Describe the TIBC (total iron binding capacity).
Indirect measurement of iron-binding capacity of transferrin, performed by adding an excess of iron to plasma to saturate and then removing the excess
Serum transferrin receptor levels , which reflect the amount of RBC precursors available for active proliferation are increased in iron deficiency anemia
Describe tsat (% transferrin saturation)
A measure of how much serum iron is actually bound
Serum iron ÷ TIBC x 100
If someone had low iron stores, what is there TIBC?
Low iron stores, high TIBC
In Iron deficiency anemia, what changes in lab values are noted? RBC morphology?
See decreases in:
- Ferritin
–> most sensitive marker but also non-specific
- serum iron
- transferrin saturation
- Hb and Hct (decline later – takes time for this to happen)
See increases in:
- total iron-binding capacity (increase in TIBC)
RBC morphology (takes time)
- Microcytic (↓ MCV)
- Hypochromic (↓ MCHC)
What are the two types of iron? What is the difference between them?
Heme iron
Derived from animal proteins
Better absorbed, more consistent absorption (~23% more)
Less affected by dietary factors
Non-heme iron
Plant sources
Fruits and vegetables, nuts, beans, grains, iron-fortified foods/supplements
Requires acidic GI pH for absorption
What can decrease the absorption of iron?
Phytates (grains, brans)
Polyphenols/tannins (coffee/tea)
Calcium (others too)
H2RAs (antagonism), PPIs
Gastrectomy/bariatric surgery/achlorhydria
What can increase the absorption of iron?
Increased stomach acidity (increase conversion of form)
Eating heme and non-heme sources at the same time
Cook with cast-iron or stainless steel pots/pans (↑ the amount of non-heme iron)
What are some people who require more dietary intake of iron?
Endurance athletes, pregnant
What is the dietary intake of iron for pregnancy?
RDA - 27 mg/day
Vegetarian - 49 mg/day