28 - Anemia Flashcards
1
Q
What is anemia?
A
- Group of diseases characterized by decrease in either hemoglobin or volume of RBCs which results in decreased oxygen-carrying capacity of the blood
- Sign of underlying pathology rather than a disease
2
Q
How is anemia characterized?
A
- Can be characterized by RBC size (macrocytic, normocytic, or microcytic)
- Vitamin B12 & folate deficiencies are both macrocytic anemias
- Microcytic = iron deficiency
- Normocytic = recent blood loss or chronic disease
3
Q
Main causes of anemia
A
- Inadequate RBC production
- Ineffective RBC maturation (iron deficiency, vitamin B12 & folic acid deficiency)
- Increased RBC destruction
- Increased RBC loss
- More than 1 anemia & etiology can occur at the same time
4
Q
Describe the assessment for anemia
A
- 5 steps -> See How Many Red Cells (SHMRC)
- S = signs & sx (look for first)
- H = hemoglobin or hematocrit (if low = anemic)
- M = MCV (indication of average RBC size)
- R = RDW (or peripheral blood smear) – are all cells the same size? Do you believe the MCV? – normal RDW = 11-14%
- – If MCV is normocytic, might assume that RBC’s are normal w/o anemia
- – If RDW is high, means big difference between size of RBC’s => anemia
- – Iron deficiency anemia produces microcytic MCV, but may start off as normal & RDW will be high (above normal) b/c don’t have all the same size RBCs
- C = check reticulocytes & likely deficiencies
- – Reticulocytes = immature RBC’s released from bone marrow
- Be aware of mixed anemias
5
Q
General clinical presentation of anemia
A
- CNS = fatigue, headache, dizziness
- HEENT (head, eyes, ears, nose, throat) = pale skin, conjunctivae, & nail beds; vertigo
- Respiratory = dyspnea on exertion
- CVS = tachycardia, palpitations
- GI = anorexia
- Other = cold intolerance, loss of skin tone
6
Q
What labs are used to assess anemia?
A
- CBC (Hbg, Hct including RBC indices – MCV, MCHC, RDW)
- Iron indices (ferritin), vitamin B12, folate
- Reticulocyte index
- Stool sample for occult blood
7
Q
Lab definition of anemia
A
- Males = Hgb < 130 g/L
- Females = Hbg < 120 g/L
8
Q
What do the values of MCV and RDW mean in regards to anemia?
A
- Microcytic (MCV < 80 fL)
- Normal RDW = ACD (anemia of chronic disease)
- High RDW = iron deficiency (ferritin < 20 mcg/L)
- *Don’t use RDW to differentiate between IDA & ACD
- Normocytic (MCV 80-100 fL)
- Normal RDW = CKD; ACD; hypothyroidism
- High RDW = hemolytic anemia; sickle cell anemia
- *Check reticulocytes
- Macrocytic (MCV > 100 fL)
- Normal RDW = liver disease; EtOH
- High RDW = B12/folate deficiency
9
Q
What is the most common cause of anemia?
A
Iron deficiency
10
Q
Presentation of iron deficiency anemia
A
- Clinical presentation = dry rough skin, brittle nails, dry damaged hair or hair loss, restless leg syndrome (b/c epithelial cells that rapidly divide need iron, so w/ iron deficiency they can’t divide as quickly & will dry up)
- Signs of advanced tissue iron deficiency = cheilosis (cracking at corners of mouth) & koilonychia (spooning of fingernails)
11
Q
Describe how to determine severity of anemia sx
A
- Mild = little to no sx
- Moderate = sx affecting life; fatigue, weakness, difficulty concentrating
- Severe = unable to tolerate mild exercise, may be symptomatic at rest
12
Q
Describe the lab values measured in regards to iron
A
- Serum ferritin (20-300 mcg/L)
- Reflects tissue iron stores (liver, spleen, bone marrow)
- Acute phase reactant (may be elevated in infection, inflammation, malignancy)
- If ferritin is low (< 20) probably deficient in iron
- If ferritin high (> 100) likely have a chronic disease & must check TSAT
- TSAT (%) = serum iron/TIBC * 100%
- Amount of iron readily available (how much iron is in blood & available to bone marrow to make new RBCs)
- Normal = 14-50%
- Usually only measured if ferritin is normal (or in CKD)
- Basically, saying how much transferrin is bound to iron in the blood
- TIBC total iron binding capacity (47-72 umol/L) – indirect measure of iron-binding capacity of serum transferrin
- Serum iron (7-27 umol/L) – concentration of iron bound to transferrin
13
Q
What are the lab findings of iron deficiency anemia?
A
- Hgb = low
- MCV = low (microcytic)
- MCH = low (microcytosis or hypochromia)
- MCHC = low (hypochromic = less pigment, so pale)
- Normochromic or hypochromic = Hgb content
- Independent of cell size, so more useful than MCH in distinguishing between microcytosis & hypochromia
- Low MCHC = hypochromia (microcyte w/ normal hemoglobin concentration will have low MCH but normal MCHC); most often seen in iron-deficiency anemia
- RDW = high (variation in size of RBCs)
- Reticulocytes = low-normal (impaired RBC production)
- Serum ferritin = low (< 20 mcg/L)
- Serum ferritin is proportional to total iron stores, so is the best indicator of iron deficiency or iron overload
- Low serum ferritin is basically diagnostic of IDA
14
Q
What is MCH and what is the most common cause of elevated MCH?
A
- Amount of hemoglobin in an RBC & usually increases or decreases w/ the MCV
- Most common cause of elevated MCH is macrocytosis (vit B12 or folate deficiency)
15
Q
What is MCHC?
A
Concentration of hemoglobin per volume of cells
16
Q
Risk factors for IDA
A
- Inadequate intake/increased requirements
- Adolescents (poor diet, rapid growth)
- Menorrhagia, pregnancy/lactation
- Vegetarians (especially vegans)
- Athletes (increased RBC production, iron loss, sweat)
- Chronic renal failure px
- Blood loss – regular blood donors, surgery, drugs (NSAIDs, ASA, anticoagulants; antacids can decrease iron absorption)
- Genetic – family history of hematologic disorders; ethnicity
17
Q
Goals of tx for IDA
A
- Improve clinical signs & sx of anemia
- Restore Hgb levels & MCV to normal & replenish iron stores
18
Q
Principles of tx for IDA
A
- Determine cause of iron deficiency & treat underlying disease if possible
- Fecal occult blood test (FOBT) to check for GI bleeding/colon cancer screening
- Replenish iron stores
- Options = increase dietary iron (very hard to get rid of deficiency w/ just dietary intake), oral iron supplementation, IV iron supplementation, blood transfusions
19
Q
Causes of IDA
A
- Increased iron loss (ex: menses, GI neoplasms, blood donation, peptic ulcer, hemorrhoids, drugs like ASA, NSAIDs, anticoagulants)
- Increased demand for iron (ex: rapid growth in infancy/adolescence, pregnancy, EPO deficiency)
- Decreased iron intake/absorption (ex: inadequate diet, gastric surgery, Crohn’s disease, celiac disease, achlorhydria/low gastric acid, acute or chronic inflammation, H. pylori infection)
20
Q
What is the difference between heme iron and non-heme iron and what are sources of each?
A
- Heme iron Fe2+ (ferrous iron)
- Meat, poultry, seafood
- 3x more absorbable vs. non-heme iron (has different receptor that it binds to in gut & less things block its absorption)
- Absorption decreased by content of calcium in meal (Ca2+ supplements, milk/dairy)
- Non-heme iron Fe3+ (ferric iron)
- Vegetables, fruits, dried beans, nuts, grains
- Absorption increased by gastric acid & ascorbic acid-rich foods
21
Q
What decreases non-heme iron absorption?
A
- Phytates (bran, oats, rye fiber)
- Tannins (herbal teas) – don’t recommend tea if trying to keep iron levels up
- Phosphates
- Polyphenols (tea/coffee)
- Calcium supplements
- Milk/dairy
- Antacids, PPIs, H2 blockers
22
Q
Recommended dose of oral iron for IDA? How should it be taken?
A
- Recommended dose for IDA = 150-200 mg elemental Fe/day (or 2-3 mg/kg/day)
- Elderly = 15-50 mg/day may be effective (especially if mild deficiency)
- Take on empty stomach or at least 1 h before meal or 2 h after meal
- May need to take w/ meals to decrease GI side effects (decreases absorption)
