Understanding Lab Tests for Hypocomplementemic Urticarial Vasculitis
Written by Private MD Labs Medical Writing Team • Last Updated: September 8, 2025
Hypocomplementemic urticarial vasculitis (HUV) is a rare autoimmune disorder characterized by chronic hives (urticaria) and inflammation of small blood vessels (vasculitis). A key feature of this condition is abnormally low levels of complement proteins in the blood, which are essential components of the immune system.
Top Recommended Test
Complement Component C1q
This test measures C1q complement levels, which are persistently low in this rare autoimmune disorder. The reduced C1q levels are associated with the formation of anti-C1q antibodies that contribute to the blood vessel inflammation characteristic of this condition, making it a key diagnostic marker.
2907 reviews
Diagnosing Hypocomplementemic Urticarial Vasculitis
The diagnosis of HUV relies on both clinical presentation and specific blood tests that measure complement protein levels. These tests are fundamental for confirming the diagnosis, as persistently low complement levels distinguish this condition from other forms of chronic urticaria and vasculitis.
Other Relevant Tests
Complement Component C4c
This test measures C4c levels in the blood, which are characteristically low in hypocomplementemic urticarial vasculitis. The decreased levels occur due to consumption of complement proteins during the ongoing inflammatory process affecting small blood vessels, making this test essential for diagnosis.
2907 reviews
Understanding Your Test Results
Low levels of both C1q and C4c complement components, along with appropriate clinical symptoms, support the diagnosis of hypocomplementemic urticarial vasculitis. These tests may need to be repeated over time to monitor the condition and treatment response, as complement levels can fluctuate with disease activity.
Important Considerations
The information here is for educational purposes only and is not a substitute for professional medical advice. Always consult with a healthcare provider for diagnosis and treatment. Additional testing and clinical evaluation may be necessary for a complete assessment.
