FXII deficiency tends to be identified during presurgical laboratory screening for bleeding disorders.

[citation needed] There is concern that individuals with FXII deficiency are more prone to thrombophilic disease,[1] however, this is at variance with a long-term study from Switzerland.

[2] The diagnosis is confirmed by an assay detecting very low or absent FXII levels.

[2] In hereditary angioedema type III an increased activity of factor XII has been described.

[citation needed] The condition was first described in 1955 based by blood testing of a patient named John Hageman.