Preferred Sample Type
Suitable Specimen Types
- Serum
Specimen Transport
First class post to Ref Lab.
Sample Processing in Laboratory
Usual to BHH.
Sample Preparation
Centrifuge and separate serum, store serum at -20 deg/celcius if not sent same day.
Transport to Ref Lab only on Monday-Thursday. i.e AVOID the weekend.
Turnaround Time
10 working daysSample Stability
Store separated serum at -20 ºC if not sent to referral laboratory same day
Procollagen peptide Type 3 (P3NP or PIIINP)
General Information
Collagen is formed initially with pro-peptides at both ends. In the liver the majority of collagen is either type 1 or type 3. The removal of the propeptides promotes development of collagen fibrils. The pro-peptides may either be retained in the matrix or released into the circulation. Fibrosis occuring in the liver results in the deposition of collagen and release of propeptides, predominantly P3NP. Increased P3NP is seen in various liver diseases in which fibrosis/cirrhosis is a major feature e.g. alcoholic liver disease, primary sclerosing cholangitis and also in non-liver diseases where fibrosis is a feature e.g. myelofibrosis, systemic sclerosis etc.
Methotrexate is a successful form of treatment for psoriasis and rheumatoid arthritis (RA). It has, however, been noted that prolonged exposure can result in irreversible hepatic fibrosis the risk of which is idiopathic but associated with cumulative doses of more than 1.5g (usually encountered in psoriasis as lower doses are used in RA). Previously it was advised that a liver biopsy be considered after each cumulative 1.5g methotrexate. In 1996 it was shown that serum P3NP concentrations were predictive of the development of hepatic fibrosis. Continually raised P3NP concentrations were found to be associated with fibrosis in 78-100% of cases, but were only seen in 15-18% of subjects with a normal liver on biopsy. Current guidelines on the use of methotrexate in psoriasis suggest P3NP measurements be carried out annually and three monthly after a raised value.
Patient Preparation
Haemolysed samples are not acceptable.
Serum from red top or SST tubes is suitable for analysis.
Notes
Reference Range
P3NP references ranges in use from 1st April 2014
Paediatric reference ranges
MALE:
|
4 – 11 years |
11.9 – 29.4 µg/L |
|
12- 16 years |
11.9 – 51.8 µg/L |
|
17- 18 years |
6.6 – 42.1 µg/L |
FEMALE:
|
4 – 10 years |
12.7 – 33.5 µg/L |
|
11 – 12 years |
13.7 – 52.5 µg/L |
|
13 – 14 years |
10.1 – 37.3 µg/L |
|
15 – 18 years |
6.6 – 18.8 µg/L |
Adult reference ranges:
Green (safe) <10.4 µg/L
Amber (warning) 10.4 – 12.9 µg/L
Red (action) >12.9 µg/L
Adult patients on methotrexate:
3.3 – 9.6 µg/L
Source of Reference Range
Provided by Reference LaboratorySpecifications
- EQA Scheme?: Yes
- EQA Status: Sample exchange scheme in place