1. The Role of Hematology in the Diagnosis of
Hemophilia A
Brianna McKenna and Kimberly Campbell | MLT-1042 Hematology l Terri Domenici | 11/05/2018
Hematology and Diagnosis
Hemophilia A can be inherited and in rare instances can be an
acquired clotting disorder. It causes the patient’s blood to not clot
properly. Hemophilia A can be seen as early as infancy. Symptoms
depend on the severity of the disorder, which ranges from mild to
moderate to severe. Mild Hemophilia A has 5-40% working clotting
factors in the blood, moderate has 1-5%, and severe has less then
1%. Hematology will perform a CBC on an automatic hematology
analyzer using an EDTA whole blood specimen. They will also
perform PT, aPTT, Fibrinogen, and clotting factor tests on a semi-
automated coagulation analyzer using 3.2% sodium citrate whole
blood specimen. An increased time in the aPTT test helps the doctor
diagnose Hemophilia A.
Pathophysiology
Hemophilia A is an X-linked recessive gene mutation resulting in a
factor VIII deficiency. This disorder prevents the blood from clotting
properly, which can lead to prolonged bleeding. The deficiency stops
the clotting cascade before a clot can form.
• Organs and systems affected: muscles, joints, kidneys, the GI
tract, and the brain
• Effects: Acute pain, swelling, restriction on movements, arthritis,
blood in urine, black and bloody stool, changes in mental status,
seizures
• Population at risk: More common in men than women
Required Specimen
• Proper collection procedure: Venipuncture
• Proper specimen container or tube: EDTA whole blood tube and
3.2% sodium citrate whole blood tube
Instrument Methodology
Specimen Analysis Procedure
Diagnostic Results
• Automated CBC: Is normal unless the patient has heavy bleeding
or had bled for a long period of time. If there is heavy blood loss
the hematocrit, hemoglobin, and red blood cell count can be low
• Activated Partial Thromboplastin Time (APTT) Test: The time will
be longer with patients with hemophilia A because factor VIII is
measured here.
• Prothrombin Time (PT) Test: Normal
Interfering Substances
Smear Review
This would be a smear of a patient that had/has heavy bleeding or
has experienced prolong bleeding. The normal smear will be
normochromic/normocytic. A smear with blood loss is hypochromic.
References
Hemophilia. (2011, September 13). Retrieved from
https://www.cdc.gov/ncbddd/hemophilia/diagnosis.html
Hemophilia A. (n.d.). Retrieved from https://rarediseases.org/rare-
diseases/hemophilia-a/
Kamal, A. H., Tefferi, A., & Pruthi, R. K. (2007). How to Interpret and
Pursue an Abnormal Prothrombin Time, Activated Partial
Thromboplastin Time, and Bleeding Time in Adults. Mayo Clinic
Proceedings,82(7), 864-873. doi:10.4065/82.7.864
Klatt, E. C. (n.d.). CBC. Retrieved from
https://library.med.utah.edu/WebPath/HEMEHTML/HEME024.html
Magazine, L. (2018, May 17). Haemophilia: What To Eat And What
To Avoid. Retrieved from https://www.longevitylive.com/anti-aging-
beauty/haemophilia-eat-avoid-nutrition-bleed/
Pippard, M. J. (2017). Microcytic anaemias in childhood and iron-
refractory iron deficiency anaemia. British Journal of
Haematology,177(2), 167-168. doi:10.1111/bjh.14558
Preanalytical: Specimen is checked for label and correct volume along
with looking for clotting. Whole blood is used. The barcode or patient
info is scanned or manually entered into the system.
Analytical: Patient specimen in an EDTA tube is loaded into an
analyzer such as the Sysmex XN 550 to obtain a CBC. The plasma
from a sodium citrate tube is loaded in a KC1 Delta to get the APTT
results. If there is heavy blood loss with a low hematocrit and an
abnormal CBC, then a smear review is required.
Post Analytical: Abnormal CBC results are flagged in the computer
and printout. The APTT must be reviewed and determined if normal or
abnormal. The smear is reviewed for abnormal morphology and
manually entered into the LIS.
• The fasting state of the patient can affect
plasma turbidity. This can interfere with PT
and aPPT optical systems and cause false
results.
• Time between collection and testing can
interfere with results. Waiting more than 4
hours after collection to perform an aPTT
can cause inaccurate results.
• A high hematocrit can interfere with results
due to the ratio of plasma to anticoagulant
being altered.
KC1 Delta is one of many semi-
automatic coagulation instruments
used to detect clots. The time
required for plasma to clot is
recorded.
This is used to determine
concentration of clotting factors.
prothrombin times (PT), Activation
partial thromboplastic times
(aPTT), and fibrinogen
SysmexXN-550 is one example
of an automated hematology
analyzer used to obtain a CBC
on a patient.
