revised

1. The Role of Hematology in the Diagnosis of a
Patient with Sickle Cell Anemia
Melissa Ward and Edmarie Velez-Rivera Terri Domenici | College of Southern Maryland
Hematology and Diagnosis
Sickle cell disease (SCD) is characterized by a point mutation that replaces
adenine with thymidine in the sixth codon of the β-globin gene.
The test for diagnosis is to test for the presence of HGB-S.
Newborns in the U.S. are automatically tested for sickle cell as part of the
newborn screening. Chorionic villus sampling can be performed at 8-12
weeks' gestation to obtain DNA.
If positive for HGB-S further testing, genetic testing, is needed to determine
if one or two genes are affected.
Hemoglobin electrophoresis differentiates individuals who are homozygous
for HbS from those who are heterozygous.
Pathophysiology
Sickle cell anemia is an inherited form of anemia, a condition in which there
aren't enough healthy red blood cells to carry adequate oxygen throughout your
body.
.The abnormal hemoglobin causes red blood cells to become rigid, sticky and
misshapen.
Organs affected: Spleen, Kidney, and Bone Marrow
•Effects: Slow blood flow, lack of oxygen circulating, autosplenectomy, pains,
infection, abnormal growth
•Population at risk: African descendant
Acceptable Specimen
Automated and Semi-Automated CBC Analyzer
Treatment
WBC differential
CBC Results
An automated analyser is a medical laboratory
instrument designed to measure different chemicals and
other characteristics in a number of biological samples
quickly, with minimal human assistance.
These measured properties of blood and other fluids may
be useful in the diagnosis of disease.
Multiple methods of introducing the sample, most will take
the whole tube to help prevent human error.
No experience is needed to operate this analyzer but a
medical technologist is needed to interpret the result.
Interfering Substances
• Red Blood Cells (RBCs) Transfusion
• Helps with oxygen delivery in the body since the donor’s RBCs have normal
hemoglobin in them
• Decreases vaso-occlusion so that the RBCs flow freely
• Longer RBC longevity
References
• Sickle cell anemia. (n.d.). Retrieved March 07, 2017, from
https://medlineplus.gov/ency/article/000527.htm
• Sickle cell disease. (2017, February 09). Retrieved March 07, 2017, from
http://sicklecelldisease.bloodjournal.org/
• Mayo Clinic Staff Print. (2016, December 29). Sickle cell anemia. Retrieved
March 08, 2017, from http://www.mayoclinic.org/diseases-conditions/sickle-
cell-anemia/home/ovc-20303267
• Gibbons, G. H., M.D. (2016, August 2). How is Sickle Cell Disease
Treated? Retrieved March 02, 2017,
from https://www.nhlbi.nih.gov/health/health-topics/topics/sca/treatment
• Stepwards. (2016, November 26). Sickle Cell Disease/Sickle Cell
Anemia. Retrieved March 02, 2017,
from http://www.stepwards.com/?page_id=792
• Thompson, G., MD. (2015, February 20). Blood Transfusions for Sickle
Cell Disease. Retrieved March 02, 2017, from http://www.webmd.com/a-
to-z-guides/blood-transfusions-for-sickle-cell-disease
Smear Review
In a peripheral smear review you may see sickle cells, target
cells, pappenheimer bodies, Howell-Jolly bodies, absence of polychromasia,
and polychromatophilic RBCs.
Sickle cells and target cells are in image 1 and pappenheimer bodies and sickle
cells in image 2
Image 1 Image 2
• Hemoglobin level is 5-9 g/dL
• Hematocrit is decreased to 17-29%
• Total leukocyte count is elevated to 12,000-20,000 cells/mm 3 (12-20 X 10
9/L), with a predominance of neutrophils
• Platelet count is increased
• Erythrocyte sedimentation rate is low
• The reticulocyte count is usually elevated, but it may vary depending on the
extent of baseline hemolysis
• Peripheral blood smears demonstrate target cells, elongated cells, and
characteristic sickle erythrocytes
• Presence of RBCs containing nuclear remnants (Howell-Jolly bodies)
indicates that the patient is asplenic
• Results of hemoglobin solubility testing are positive, but they do not
distinguish between sickle cell disease and sickle cell trait
Other testing
• Measurement of blood urea nitrogen, serum creatinine, and serum
electrolytes can be useful. Assays of lactic dehydrogenase and haptoglobin
are useful but not required. Elevated levels of lactic dehydrogenase support
the diagnosis of hemolysis being released from destroyed RBCs. Decreased
levels of haptoglobin confirm the presence of hemolysis.
• Hemoglobin electrophoresis
• •IEF (isoelectric focusing)
• HPLC (High performance liquid chromatography)
Semi-automated CBC analyzers have a higher risk of
human error.
Some analyzers require the sample to be placed into
another tube or cup for processing.
Less safe than the automated analyzers.
The types of tests required include enzyme levels, such
as many of the liver function tests, ion levels, and other
tell-tale chemicals, like glucose, serum albumin, or
creatinine.
Severity of disease increases with the leukocyte count
Sometimes the cause of a low white blood cell count can't be determined.
Known causes of a low white blood cell count (leukopenia) include:
Infections, such as viral infections and HIV, Autoimmune disorders, such as
lupus
Certain medications, especially those used in chemotherapy and some
antibiotics
Radiation therapy
Bone marrow disease, such as leukemia or myelodysplastic syndromes
White blood cells help fight infection in your body. A normal white blood cell
count ranges from 4,500 to 10,000 cells per microliter of blood. A mild decrease
in white blood cells below 4,500 cells per microliter doesn't necessarily indicate
a serious illness. However, a dangerously low white blood cell count increases
the risk of serious infection.
However Sickle cell full and trait only effect your red blood cells.
Blood collection procedure:
Venipuncture
Proper specimen tube: EDTA/Pink
Tube
No special preservatives or handling
instructions
The sickle cell test looks for the abnormal hemoglobin or HgbS, you can get a
false positive in those with the sickle cell trait because the have some of the
abnormal Hgb S
Having a blood transfusion within 4 months of the test can cause a
false negative result because of the normal Hgb A in the donors blood.