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PTD - 273

Test Directory -  Procollagen III N-terminal peptide


Procollagen, PIIINP, P3NP

Clinical Indications

Monitoring for hepatic fibrosis, particularly in patients receiving methotrexate treatment who should be checked at three to six month intervals.

Request Form 

Combined Pathology Blood form (Yellow/Black)


Analysed by Protein Reference Unit, Sheffield, if specific criteria met.

Specific Criteria

Patient on methotrexate therapy

Patient Preparation

None required.



The usefulness of P3NP as an indicator of fibrosis is limited in children as levels are variable and may be physiologically raised due to growth spurts.

Turnaround Time

Two to three weeks




2 mL


Yellow top (SST) tube

Causes for Rejection

Unlabelled sample; delay in reaching the laboratory; sample in SST tube; assay performed within the previous three months

Reference Range


Age Range

Procollagen Type III Peptide ug/L

Birth - 2 years

10.0 - 50.0

2 - 4 years

5.0 - 15.0

5 - 10 years

5.0 - 10.0

11 - 14 years (Male)

5.0 - 10.0

11 - 14 years (Female)

8.0 - 15.0

15 - 19 years (Male)

8.0 - 20.0

15 - 19 years (Female)

2.0 - 8.0

20 - 65 years

1.7 - 4.2

Reference; Protein Reference Unit Handbook, 9th Edition 2007


PIIINP is a sensitive indicator of hepatic fibrosis, but may be raised in other conditions, particularly active connective tissue disease.

A liver biopsy should be considered if there are three PIIINP levels above 4.2 ug/L or two levels above 8.0 ug/L over a 12 month period. A liver biopsy should also be considered if the pre-treatment level is above 8.0 ug/L.

Indications for considering withdrawal of methotrexate are elevation of P3NP above 10 ug/L in at least 3 samples in one 12 month period.

Lab. Handling

Processing: Aliquot and store at 4C in separating fridge (CB39).
Referral:  P3NP and send or BPRO and save at -20C in separating freezer (CB40)


Version 1.0 / July 2014                                                                                                           Approved by: Consultant Biochemist