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Combination of tests to confirm the diagnosis of Severe Congenital Protein C Deficiency

How to Test for SCPCD

Diagnolic Test Desk

SCPCD diagnosis can be confirmed BY A COMBINATION OF:


Protein S assay(low PC levels but normal Protein S levels are suggestive of SCPCD)4

PC antigen5

Full blood count (Hemoglobin, White blood cells, Platelets)5,6



Prothrombin time (PT)2,5

Activated partial prothrombin time2,5

Genetic analysis2

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


Premature infantsa
Day 1
Antigen: 28% (12-44)
Day 5
Antigen: 31% (11-51)
Full-term infantsb
Day 1
Chromogenic: 36% (24-44)
Clotting: 32% (24-40)
Day 3
Chromogenic: 44% (28-54)
Clotting: 33% (24-51)
aData obtained using ELISA (Protein C) method

bData obtained using Stachrom Protein C and Staclot Protein C

Adapted from Price 20112


  1. Chalmers E, et al. Purpura fulminans: recognition, diagnosis and management. Archives of Disease in Childhood. 2011;96(11):1066-1071.

  2. Price VE, et al. Diagnosis and management of neonatal purpura fulminans. Semin Fetal Neonatal Med. 2011;16(6):318-22.

  3. Goldenberg N, Manco-Johnson M. Protein C deficiency. Haemophilia. 2008;14(6):1214–1221.

  4. 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.

  5. Khor B, et al. Laboratory tests for protein C deficiency. Am. J. Hematol. 2010;85:440–442.

  6. Tairaku S, et al. Prenatal genetic testing for familial severe congenital protein C deficiency. Hum Genome Var. 2015;2:15017.

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