C1- inhibitor


Included as part of the diagnosis in the investigation of angioedema.




The result is given as normal, elevated or lowered as percentage of normal sera.

Reference range

72-153% of normal sera.


C1-inhibitor is one of the six major protease inhibitors of blood; it inhibits clotting factors XIa, XIIa, plasmin and kallikrein.

C1-inhibitor results under the lower reference range limit suggests hereditary angioedema type 1 (HAE type 1) and should primarily lead to new tests for verification of the result, and then further investigation for the final determination of diagnosis (including additional investigation of other complement factors).

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Packages and other tests

View other packages Hereditary angioedema (HAE) (571). View other tests C1q, C3, C4, C3d, C4d

20 years experience