How to Test for SCPCD
SCPCD diagnosis can be confirmed BY A COMBINATION OF:
PROTEIN C (PC) ACTIVITY ASSAY1,3
Protein S assay1 (low PC levels but normal Protein S levels are suggestive of SCPCD)4
Full blood count (Hemoglobin, White blood cells, Platelets)5,6
Prothrombin time (PT)2,5
Activated partial prothrombin time2,5
PC level testing in parents1
PC activity assay and PC antigen
MRI (to check for cerebral venous thrombosis)1
Given possible confounding factors, PC deficiency should be confirmed using multiple methods.2
PC testing in parents, as well as other family members, is recommended to determine if the deficiency is genetic and whether it is a homozygous or heterozygous mutation.2 A partial reduction in PC levels in both parents is highly suggestive of SCPCD in the affected child.1
PC activity levels are mostly undetectable in PC deficient-homozygote neonates, therefore the age-specific references below, according to Price et al., are relevant when interpreting results.
Levels of PC mature later than many other coagulation proteins, which explains why PC levels are lower in healthy term infants than adults.3
Clotting: 32% (24-40)
Clotting: 33% (24-51)
bData obtained using Stachrom Protein C and Staclot Protein C
Adapted from Price 20112
Chalmers E, et al. Purpura fulminans: recognition, diagnosis and management. Archives of Disease in Childhood. 2011;96(11):1066-1071.
Price VE, et al. Diagnosis and management of neonatal purpura fulminans. Semin Fetal Neonatal Med. 2011;16(6):318-22.
Goldenberg N, Manco-Johnson M. Protein C deficiency. Haemophilia. 2008;14(6):1214–1221.
Libourel EJ, et al. Protein C/S ratio, an accurate and simple tool to identify carriers of a protein C gene mutation. British Journal of Haematology. 2002;118:615–618.
Khor B, et al. Laboratory tests for protein C deficiency. Am. J. Hematol. 2010;85:440–442.
Tairaku S, et al. Prenatal genetic testing for familial severe congenital protein C deficiency. Hum Genome Var. 2015;2:15017.