From the Guidelines
Hemophilia testing should involve a combination of blood tests, including activated partial thromboplastin time (aPTT) and specific factor assays, to diagnose and determine the severity of this inherited bleeding disorder, as recommended by recent studies 1. The primary tests for hemophilia include:
- Activated partial thromboplastin time (aPTT), which is typically prolonged in hemophilia patients
- Specific factor assays that measure the exact levels of clotting factors VIII (hemophilia A) or IX (hemophilia B) Additional tests may include:
- Prothrombin time (PT)
- Complete blood count (CBC)
- Genetic testing to identify specific mutations and determine carrier status Testing should be performed in specialized coagulation laboratories with expertise in bleeding disorders, as emphasized by 1 and 1. Early diagnosis is crucial as it allows for appropriate prophylactic treatment to prevent joint damage and life-threatening bleeds, as highlighted by 1. Patients with a family history of hemophilia or those experiencing symptoms like easy bruising, prolonged bleeding, or spontaneous joint bleeds should undergo testing promptly. The severity of hemophilia is classified based on factor levels: severe (<1%), moderate (1-5%), or mild (5-40%), with treatment approaches varying accordingly, as discussed in 1 and 1.
From the Research
Hemophilia Test Overview
- Hemophilia is a genetic disorder that impairs the body's ability to make blood clots, a process needed to stop bleeding 2.
- The diagnosis of hemophilia involves a combination of clinical assessment, laboratory tests, and family history 2.
Laboratory Tests for Hemophilia
- Routine screening tests for hemophilia include a complete blood cell count, platelet count, prothrombin time, and activated partial thromboplastin time (aPTT) 2.
- An isolated prolongation of the aPTT may indicate low levels of factors VIII, IX, or XI 2.
- Accurate measurement of clotting factors VIII (FVIII) or IX (FIX) is vital for comprehensive diagnosis and management of patients with hemophilia A or B 3.
Factor VIII and Factor IX Activity Measurements
- The one-stage activated partial thromboplastin time (aPTT)-based clotting assay is the most commonly used method for testing FVIII or FIX activities 3.
- FVIII and FIX chromogenic substrate assays are alternative methods that assess the activation of factor X 3.
- The choice of reagent or methodology can strongly influence the resulting activity, and discrepancy between one-stage and chromogenic reagents has been demonstrated in some patients 3.