Separated serum or plasma may be stored up to 5 days at 2-8 C, otherwise please freeze.
For more information on the test refer to the link below:
Units: ug/L
Reference interval: 2.3 - 6.4 ug/L
In patients on methotrexate for psoriasis, a value less than 4.2 ug/L suggests liver fibrosis is unlikely.
Turnaround time is variable as samples are batched. My take up to 1 month.
Type 3 collagen is present in some soft tissues, and is the predominant collagen in granulation tissue.
P3NP is a peptide produced during type 3 collagen synthesis; the level in plasma reflects the rate of type 3 collagen synthesis in the whole body.
P3NP has been reported to be a useful marker of liver fibrosis in patients on methotrexate therapy for psoriasis.
Patients taking methotrexate long term are at risk for liver fibrosis and periodic liver biopsies have been recommended. Studies indicate that in such patients, periodic (3-monthly) screening with P3NP significantly reduces the need for liver biopsies as no patients with P3NP less than 4.2 ug/L had fibrosis on liver biopsy.
P3NP correlates well with ongoing fibrogenic activity in the liver and is therefore also elevated in other liver conditions such as primary biliary cirrhosis or alcoholic hepatitis.
There are numerous other causes of an increase in P3NP. The list includes exercise, psoriatic arthritis, soft tissue damage, supplementation with testosterone and/or growth hormone supplementation, myeloproliferative disorders, polycythema vera, malignancies and following myocardial infarction.
P3NP levels increase significantly during growth making it difficult to interpret levels in children. The significance of P3NP levels in patients over 70 years of age has not been determined.
The positive predictive value of an elevated P3NP level is low, and even if 50% of levels are >4.2 ug/L, most patients will not have cirrhosis.
When using the Manchester protocol, P3NP is measured 3 monthly. Indications for liver biopsy include:
- Elevation of pre-treatment P3NP above 8 ug/l
- Elevation of P3NP above 4.2 ug/l on at least three samples in a 12 month period.
- Elevation of P3NP above 8 ug/L on consecutive samples
References
1. Zachariae H et al., Br J Dermatol 2001;144(1):100-3
2. Maurice PD et al. Br J Dermatol 2005; 152(3):405-8
3. Chalmers RJ, Kirby B, Smith A et al. Replacement of routine liver biopsy by procollagen III aminopeptide for monitoring patients with psoriasis receiving long-term methotrexate: a multicentre audit and health economic analysis. Br J Dermatol. 2005;152:444-450
Emails to chemicalpathologist@adhb.govt.nz will receive priority attention from the on-call chemical pathologist.
If the query concerns a specific patient please include the NHI number in your email.
If email is not a suitable option, please contact the on-call chemical pathologist via Lablink (Auckland City Hospital ext. 22000 or 09-3078995).
Individual chemical pathologists may be contacted but will not be available at all times.
After-hours : contact Lablink (Auckland City Hospital ext. 22000 or 09-3078995) or hospital operator for on duty staff after hours.
Dr Samarina Musaad (Clinical Lead) : SamarinaM@adhb.govt.nz ext. 22402
Dr Cam Kyle: CampbellK@adhb.govt.nz ext 22052
Dr Weldon Chiu: WeldonC@adhb.govt.nz ext. 23427
Dr Campbell Heron: CHeron@adhb.govt.nz ext. 23427
Dr Sakunthala Jayasinghe: Sakunthala@adhb.govt.nz ext. 23427
P3NP
Sendaway to WAIKATO Health Laboratory
Plain serum
Please s end to Labplus Frozen (preferred), stable at 2-8 C for 5 days.