FX levels are low at birth and should be compared with gestationally age-matched normal ranges before a deficiency is diagnosed in the neonate. FX levels in healthy full-term infants average 0.40 (SD ± 0.14) IU/mL and do not approximate adult values until after age 6 months.38
Because FX is synthesized in the liver, liver disease may result in decreased FX levels, along with the other liver-produced factors including prothrombin, FV, FVII, and FIX.
Vitamin K deficiency and warfarin use also result in decreased levels of FX.
Acquired FX deficiency occurs in up to 5% of patients with amyloidosis due to adsorption into splenic amyloid fibrils.39 There have been reports of acquired FX deficiency with cancer, myeloma, infection, and use of sodium valproate. Acquired inhibitors to FX have been identified in burns, respiratory infections, and exposure to topical thrombin.40
Rare Coagulation Disorders Resource Room, an extension of the RBDD Registry (eu.rbdd.org), was developed in collaboration with the Indiana Hemophilia & Thrombosis Center (www.innovativehematology.org).
The Resource Room serves as a platform to promote international collaboration to increase knowledge of these very rare disorders and to improve the care of affected individuals. The international RBDD mission, under the leadership of Dr. Peyvandi, will continue to be expanded over time.
The Resource Room thanks all contributing authors of the website articles that have made this valuable information available to the global community of both individuals affected with rare coagulation disorders and their healthcare providers.
