Anemia- Diagnosis
Hematological / Oncological
Context
- Anemia, or deficient or malfunctioning red blood cells (RBC), is the most common blood disorder that affects ~25% of people globally.
- Three mechanisms: Blood loss, decreased RBC production, and increased RBC destruction.
- Risk factors for anemia:
- Most commonly seen in children, females, chronically ill, and elderly
- Vegan diet -> Vit B12 deficiency anemia
- Alcoholism -> folate deficiency anemia
- Hereditary -> hemoglobinopathies
- Intestinal disorders (ie. IBD)
- Chronic diseases (ie. Kidney disease, Cancer, thyroid disease, liver disease, Rheumatoid arthritis or other autoimmune disease)
- Infections
- Menstruation
- Pregnancy
- Characterizing the anemia as microcytic, normocytic, or macrocytic using the MCV à helps to guide further investigations and management.
Diagnostic Criteria
Clinical Presentation
- Weakness, general fatigue, dyspnea, tachycardia, dizziness, cold hands/feet, pallor.
- Severity depends more on the rate of anemia development than the absolute Hemoglobin Hgb) value.
- Acute -> life-threatening symptoms.
- Chronic -> body compensates – greater loss of RBCs before symptoms appear.
Diagnostic Criteria:
- Adult non-pregnant females: Hgb < 120 g/L or Hct < 36% (0.36)
- Adult pregnant females:
- 1st trimester: Hgb < 110 g/L
- 2nd trimester: Hgb < 105 g/L
- 3rd trimester: Hgb < 110 g/L
- Adult males: < 130 g/L or Hct < 41% (0.41)
- Children and Adolescents:
- Birth (term infant): < 135 g/L
- 1 month: < 107g/L
- 2 months: < 94 g/L
- 3 – 6 months: < 95 g/L
- 6 months – 2 yrs: < 105 g/L
- 2 – 12 yrs: < 115 g/L
- 12 – 18 years:
- Males: < 130 g/L
- Females: <120 g/L
General laboratory Investigations
- CBC:
- Hemoglobin
- Hematocrit
- Complete WBC count
- Differential WBC count
- Platelet count
- MCV
- Mean corpuscular hemoglobin concentration (MCHC)
- RDW (RBC distribution width)
- Reticulocyte count
- Peripheral blood smear
Imaging
- Imaging modality depends on suspected source.
Characterize the Anemia
- Microcytic = MCV <80 fL
- Ddx:
- Iron deficiency
- Most common
- Bleeding is the leading cause
- Thalassemia
- Anemia of chronic disease
- Iron deficiency
- Additional Labs:
- Serum iron
- Total iron binding capacity (TIBC)
- Transferrin Saturation
- Serum ferritin
- Adults (ug/L):
- < 15 = diagnostic of iron deficiency
- 15-30 = probable
- >30 = unlikely
- >100 = normal
- ≥600 = consider iron overload
- Children (ug/L):
- < 12 diagnostic of iron deficiency
- 12-20 possible iron deficiency
- Adults (ug/L):
- Ddx:
- Normocytic = Normal MCV: 80-100 fL
- High reticulocyte count:
- DDx:
- Hemolytic Anemia – Inherited or Acquired
- Sickle cell disease, thalassemia, microangiopathic hemolytic anemias
- Blood loss
- Hemolytic Anemia – Inherited or Acquired
- Additional Labs:
- Serum Bilirubin
- Lactate Dehydrogenase
- Haptoglobin
- Low reticulocyte count:
- DDx:
- With Pancytopenia:
- Aplastic anemia
- Leukemia
- Bone marrow infiltration
- Myelodysplastic Syndromes (MDS)
- Myelofibrosis
- TB
- Amyloidosis
- Drugs –ie. Chemotherapy
- Non-Pancytopenia:
- Red cell aplasia
- Renal/Liver disease
- Anemia of chronic disease
- Additional Labs:
- Renal function tests
- Liver function tests
- Erythropoietin
- Bone marrow aspiration
- With Pancytopenia:
- DDx:
- DDx:
- High reticulocyte count:
- Macrocytic = MCV >100 fL
- Two types, megaloblastic (megaloblasts and hypersegmented neutrophils on peripheral smear) or non-megaloblastic.
- DDX:
- Non-megaloblastic:
- Liver disease
- Reticulocytosis
- Alcoholism
- Myelodysplasia
- Hypothyroidism
- Megaloblastic:
- B12 deficiency
- Folate deficiency
- Drugs that impair DNA synthesis (Methotrexate, chemotherapy, sulfa)
- Additional Labs:
- Serum Vit. B12
- Folate
- TSH
- Liver function panel
- Non-megaloblastic:
Quality Of Evidence?
High
We are highly confident that the true effect lies close to that of the estimate of the effect. There is a wide range of studies included in the analyses with no major limitations, there is little variation between studies, and the summary estimate has a narrow confidence interval.
Moderate
We consider that the true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different. There are only a few studies and some have limitations but not major flaws, there are some variations between studies, or the confidence interval of the summary estimate is wide.
Low
When the true effect may be substantially different from the estimate of the effect. The studies have major flaws, there is important variations between studies, of the confidence interval of the summary estimate is very wide.
Justification
Evidence comes from reliable sources, which are in relative agreement on the diagnosis and investigations of anemia.
Related Information
OTHER RELEVANT INFORMATION
Reference List
Therapeutics Initiative. Intravenous (IV) iron for severe iron deficiency. TI UBC. 2015.
Young MF, Oaks BM, Tandon S, Martorell R, Dewey KG, Wendt AS. Maternal hemoglobin concentrations across pregnancy and maternal and child health: a systematic review and meta-analysis. Ann N Y Acad Sci. 2019;1450(1):47-68.
Wang M. Iron deficiency and other types of anemia in infants and children. AFP. 2016;93(4):270-8.
Hayter J, Thomas A. Investigation and management of anaemia. Medicine. 2021 Feb 25.
Long B, Koyfman A. Emergency Medicine Evaluation and Management of Anemia. Emerg. Med. Clin. 2018;36(3):609-30.
Braunstein EM. Evaluation of Anemia. Merck Manual. 2020.
Government of Canada. First Nations and Inuit Health Branch (FNIHB) Clinical Practice Guidelines for Nurses in Primary Care – Chapter 10 Hematology, Metabolism and Endocrinology. GC. 2010.
Moses S. Anemia Chapter: Normocytic Anemia. Fpnotebook. 2020.
British Columbia Ministry of Health. Iron Deficiency- Diagnosis and Management. BC Guidelines. 2019.
RESOURCE AUTHOR(S)
DISCLAIMER
The purpose of this document is to provide health care professionals with key facts and recommendations for the diagnosis and treatment of patients in the emergency department. This summary was produced by Emergency Care BC (formerly the BC Emergency Medicine Network) and uses the best available knowledge at the time of publication. However, healthcare professionals should continue to use their own judgment and take into consideration context, resources and other relevant factors. Emergency Care BC is not liable for any damages, claims, liabilities, costs or obligations arising from the use of this document including loss or damages arising from any claims made by a third party. Emergency Care BC also assumes no responsibility or liability for changes made to this document without its consent.
Last Updated Sep 07, 2024
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