Methods for the measurement of protein c and activated protein c

A mass spectrometry-based method for screening or classifying a subject as being at risk of having disseminated intravascular coagulation (DIC), wherein the subject has been diagnosed with sepsis or septic shock, the method comprising the steps of:

• i) measuring the levels of Protein C (PROC), by carrying out a method comprising performing an enzymatic digestion of a plasma sample isolated from the subject, and measuring by using a mass spectrometer the levels of the peptide of SEQ ID NO:
• 1 (LGEYDLR), wherein the levels of SEQ ID NO:
• 1 (LGEYDLR) correspond to the levels of PROC, present in said plasma sample, and
• ii) comparing the levels obtained in step i) with a reference value,
• wherein the reference value is 600 ng/mL, and wherein a reduction of at least 20% relative to the reference value is indicative that the subject is at risk of having DIC,
• wherein the measurement of the peptide of SEQ ID NO:
• 1 (LGEYDLR) is carried out by spiking-in a labelled proteotypic peptide of SEQ ID NO:
• 1 (LGEYDLR), wherein the spike-in labelled proteotypic peptide of SEQ ID NO:
• 1 (LGEYDLR) is synthesized with at least one or more heavy amino acids.

A mass spectrometry-based method for screening or classifying a subject as being at risk of having sepsis or septic shock, the method comprising the steps of:

• i) measuring the levels of Protein C (PROC), by carrying out a method comprising performing an enzymatic digestion of a plasma sample isolated from the subject, and measuring by using a mass spectrometer the levels of the peptide of SEQ ID NO:
• 1 (LGEYDLR), wherein the levels of SEQ ID NO:
• 1 (LGEYDLR) correspond to the levels of PROC, present in said plasma sample, and
• ii) comparing the levels obtained in step i) with a reference value,
• wherein the reference value is 4000 ng/mL, and wherein a reduction of at least 30% relative to the reference value is indicative that the subject is at risk of having sepsis or septic shock,
• wherein the measurement of the peptide of SEQ ID NO:
• 1 (LGEYDLR) is carried out by spiking-in a labelled proteotypic peptide of SEQ ID NO:
• 1 (LGEYDLR), wherein the spike-in labelled proteotypic peptide of SEQ ID NO:
• 1 (LGEYDLR) is synthesized with at least one or more heavy amino acids.