Anemia, Emergency Medicine

Basics

Description

Reduction below normal in the mass of RBCs
Measured by 1 or more of the major RBC components:
- Hemoglobin (Hgb): Concentration of the major oxygen-carrying component in whole blood
- Hematocrit (Hct): Percent volume of whole blood occupied by intact RBCs
- RBC count: RBCs contained in a volume of whole blood
Adult female: Hgb <12 g/dL or Hct <37%
Adult male: Hgb <14 g/dL or Hct <42%
Normal blood count values depend on age:
- Birth: Hgb 16.5, Hct 51
- 1 yr: Hgb 12, Hct 36
- 6 yr: Hgb 12.5, Hct 37
- Adult male: Hgb 14, Hct 42
- Adult female: Hgb 12, Hct 37
Hgb/Hct depend on oxygen pressure:
- Increased in neonates and people living above 4,000 ft
Hgb, Hct, and RBC count are concentrations:
- Dependent on RBC mass and plasma volume
- Values decrease if RBC mass decreases or plasma volume increases.
Anemia is an indication of an underlying disorder or deficiency.

Etiology

Never a normal variant:
- May be the first manifestation of a systemic disorder
- Always seek a cause.
Excessive blood loss (most common cause):
- Trauma
- GI bleed
- Menstruation
Hemolysis (increased RBC destruction, RBC lifespan <100 days):
- Hypersplenism
- Autoimmune hemolytic anemia
- Mechanical trauma (prosthetic heart valves, vasculitis, thrombotic thrombocytopenic purpura [TTP], hemolytic uremic syndrome [HUS], or disseminated intravascular coagulation [DIC])
- Toxins
- Infections (malaria, babesiosis)
- Membrane abnormalities
- Intracellular RBC abnormalities (G6PD, sickle cell anemia, or thalassemia)
Decreased RBC synthesis:
- Classified by measurement of RBC size
- Hypochromic/microcytic:
  - Iron deficiency
  - Thalassemia
  - Sideroblastic
  - Chronic disease
- Normochromic/macrocytic:
  - Hypothyroidism
  - Folate deficiency
  - Vitamin B12 deficiency
  - Liver disease
  - Myelodysplasia
  - Certain leukemias
- Normochromic/normocytic:
  - Aplastic anemia
  - Chronic renal failure
  - Malignancy
  - Adrenal insufficiency
  - Hyperparathyroidism
  - Alcohol abuse
  - Acute blood loss

Diagnosis

Signs and Symptoms

Depends on: á

Rapidity of onset:
- Hypovolemia if acute
- Asymptomatic if mild and chronic

History

Underlying disease
Severity and type of anemia
Fatigue
Decreased exercise intolerance
Shortness of breath
Dyspnea on exertion
Chest pain/angina
Syncope
Blood in stool/tarry black stools
Irregular or heavy menses
Easy bruising or history of excessive bleeding

Physical Exam

Cardiovascular:
- Tachycardia, cardiomegaly, or murmurs
- Postural hypotension
Dermatologic:
- Skin:
  - Cool
  - Pallor
  - Jaundice
  - Purpura
  - Telangiectasia
  - Petechiae
  - Ecchymosis
- Spoon-shaped nails (koilonychia)
Neurologic:
- Neuropathy
- Altered mental status
Bone (especially sternal) or joint pain (sickle cell disease)
Hepatomegaly, splenomegaly
Lymphadenopathy
Findings reflect underlying disease

Essential Workup

CBC
Vital signs/orthostatics
Determine if:
- Bleeding
- Increased RBC destruction
- Bone marrow suppression
- Iron deficient

Diagnosis Tests & Interpretation

Lab

Type and crossmatch or type and screen
- Depends on severity
CBC
- RBC indices:
  - Mean corpuscular volume (MCV; normal: 80-100 ╬╝m3)
  - Mean corpuscular hemoglobin (MCH; normal: 27-34 pg/cell)
  - Mean corpuscular hemoglobin concentration (MCHC; normal: 33-36%)
- Platelet count
  - Thrombocytosis suggests:
    - Iron deficiency
    - Myeloproliferative disorders
    - Inflammation
    - Infection
    - Neoplasm
  - Thrombocytopenia suggests:
    - Bone marrow malignancy
    - Hypersplenism
    - Sepsis
    - Vitamin B12 or folate deficiency
    - Autoimmune disorders
Reticulocyte (retic) count:
- Normal 0.5-1.5% (retics/1,000 RBCs)
- Increased retic count: Increased erythropoietic response to continued blood loss or hemolysis
- Stable anemia with low retic count: Impaired RBC production
- Active hemolysis or blood loss with low retic count: Concurrent disorder
- Low retic count with pancytopenia: Aplastic anemia
- Low retic count with normal WBC and platelets: Pure RBC aplasia
Reticulocyte index (RI): Retic count (%) Ś (patient Hct/normal Hct):
- RI <2% implies inadequate RBC production.
- RI >2% implies increased RBC production with excessive RBC destruction or loss.
WBC with differential and peripheral smear:
- Leukopenia with anemia suggests bone marrow suppression, hypersplenism, or deficient vitamin B12/folate
Stool for occult blood
Electrolytes, BUN, creatinine, glucose:
- Chronic renal failure
Urinalysis:
- Hematuria
- Hemoglobinuria in hemolytic anemia
Workup strategy:
- Hypochromic/microcytic anemias:
  - Iron
  - Total iron-binding capacity
  - Transferrin saturation
  - Ferritin
- Macrocytic anemias:
  - Folate
  - Vitamin B12
  - LFT
  - Thyroid function tests
- Hemolytic anemia:
  - Rapid fall in Hgb
  - Reticulocytosis
  - Fragmented RBCs
  - Increased LDH
  - Increased indirect bilirubin
  - Decreased serum haptoglobin
  - Coombs positive
Special tests:
- Peripheral smear:
  - Helmet cells/schistocytes-microangiopathic hemolysis
  - Teardrop cells-myelofibrosis
  - Spherocytes-autoimmune hemolysis
  - Leukoerythroblastic pattern-bone marrow replacement
  - Bite cells-oxidative hemolysis
  - RBC parasites-malaria or babesiosis
  - Target cells-liver disease
  - Burr cells-uremia
  - Sideroblasts-alcoholism or myelodysplasia
  - Howell-Jolly bodies-asplenia
- Hgb electrophoresis for sickle cell/thalassemia
- Iron, iron-binding capacity, transferrin saturation, ferritin:
  - Iron deficiency
  - Iron-decreased
  - Iron-binding capacity-increased
  - Transferrin saturation-decreased
  - Ferritin-decreased
- Chronic disease:
  - Iron-decreased
  - Iron-binding capacity-decreased
  - Transferrin saturation-decreased/normal
  - Ferritin-normal/increased
- Thalassemia:
  - Iron-normal
  - Iron-binding capacity-normal
  - Ferritin-normal
- Sideroblastic anemia:
  - Iron-increased
  - Iron-binding capacity-normal
  - Ferritin-increased

Diagnostic Procedures/Surgery
Bone marrow biopsy evaluates: á

Aplastic anemia
Myelodysplasia
Bone marrow malignancy
Myeloproliferative disorders

Differential Diagnosis

Acquired versus inherited anemia
Anemia of chronic disease
Blood loss
CHF
Dilutional anemia
Hemolysis
Malignancy
Nutritional deficiency/malabsorption
Toxic bone marrow suppression

Hemolytic anemia of the newborn:
Rh antibody crosses placenta when Rh-negative mother has Rh-positive child.

Physiologic or dilutional anemia in 3rd-trimester pregnancy:
25% increase of RBC mass and 50% increase in plasma volume

Values for Hgb/Hct in healthy elderly are generally lower than in younger adults.
This lower "normal"Ł must be a diagnosis of exclusion.

Treatment

Pre-Hospital

Ongoing blood loss requires close assessment and rapid transport: á

Control bleeding to include wound packing and use of tourniquets if needed.
Two large-bore IVs

Initial Stabilization/Therapy

Airway, breathing, circulation (ABCs)
Oxygen
IV fluid resuscitation with 0.9% NS if ongoing loss/hypotension

Ed Treatment/Procedures

Depends on severity of anemia and acuteness of onset
Transfusion for hemorrhage with unstable vital signs not responding to crystalloid resuscitation.
Most anemias seen in ED are chronic and do not require immediate intervention.
Therapy for specific anemia:
- Iron deficiency:
  - FeSO4: 300 mg PO TID
  - Investigate underlying cause.
  - Increased Hgb expected in 2-3 wk
- Renal failure:
  - Endogenous erythropoietin is diminished.
  - Replace with recombinant erythropoietin
- Autoimmune hemolytic anemia:
  - Corticosteroids (prednisone 60 mg/day until response)
  - Immunosuppressive agents
  - Plasmapheresis
  - Splenectomy if splenic sequestration
- Drug-induced hemolytic anemia: Stop offending agent.
- Anemia of chronic disease: Treat underlying disease.
- Vitamin B12 deficiency:
  - Vitamin B12: 1,000 ╬╝g IM daily for 1 wk, then weekly for 1 mo, then monthly
  - Hematologic parameters normalize within 2 mo.
  - Neurologic symptoms present >6 mo may be permanent.
- Folate deficiency:
  - Folic acid: 1 mg PO daily
- Aplastic anemia
- Antithymocyte globulin
- Bone marrow transplantation:
  - Sickle cell anemia
  - Supportive care with oxygen, rehydration, analgesia
  - Treat precipitating cause.
- Leukemia:
  - Bone marrow replacement

Medication

Iron supplements
Erythropoietin for renal failure
Corticosteroids for autoimmune
Vitamin B12
Folic acid (B9)

Follow-Up

Disposition

Admission Criteria

Unstable vital signs
Ongoing blood loss
Symptomatic anemia-angina/dyspnea/syncope/neurologic symptoms
Need for transfusion
Need for aggressive evaluation
Severe anemia
- Initial, unexplained Hgb <8 g/dL
- Major difficulty in obtaining outpatient care for patients whose Hgb are significantly low or when comorbidity is present

Discharge Criteria
Discharge vast majority of stable patients for outpatient workup. á

Followup Recommendations

Newly diagnosed anemic patients need to be worked up: á

If stable for discharge from the ED, provide follow-up options for workup

Pearls and Pitfalls

Anemia is an indication of an underlying disorder or deficiency.
Severe or life-threatening cases require immediate correction via blood transfusion.
Most cases seen in the ED are chronic and do not require immediate intervention.

Additional Reading

Bryan áL, Zakai áN. Why is my patient anemic? Hematol Oncol Clin N. 2012;26:205-230.
Bunn áHF. Goldman: Goldmans Cecil Medicine. 24th ed. Philadelphia, PA: Saunders, an imprint of Elsevier Inc.; 2011.
Hoffman áR, Benz áEJ Jr, Silberstein áLE, et al. Hematology: Basic Principles and Practice. 6th ed. Philadelphia, PA: Saunders, an imprint of Elsevier Inc.; 2012.
Recht áM. Thrombocytopenia and anemia in infants and children. Emerg Med Clin North Am. 2009;27:505-523.
Rizack áT. Special hematologic issues in the pregnant patient. Hematol Oncol Clin N. 2012;26:409-432.

Codes

ICD9

280.0 Iron deficiency anemia secondary to blood loss (chronic)
285.1 Acute posthemorrhagic anemia
285.9 Anemia, unspecified
283.9 Acquired hemolytic anemia, unspecified
285.29 Anemia of other chronic disease

ICD10

D50.0 Iron deficiency anemia secondary to blood loss (chronic)
D62 Acute posthemorrhagic anemia
D64.9 Anemia, unspecified
D58.9 Hereditary hemolytic anemia, unspecified
D63.8 Anemia in other chronic diseases classified elsewhere

SNOMED

271737000 Anemia (disorder)
267530009 Acute posthemorrhagic anemia (disorder)
413533008 anemia due to chronic blood loss (disorder)
61261009 Hemolytic anemia (disorder)
234347009 Anemia of chronic disorder (disorder)

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