Procollagen-3 N-Terminal Peptide (P3NP)
Biochemistry Overview / Directory
Purpose of the test
Collagen is formed initially with propeptides 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 propeptides 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. Assay is by radioimmunoassay.
Reference Range
The normal range for serum P3NP is less than 4.2 mg/L
Sample Requirements
Serum (500 µL).
Storage and Transport
Stable at 4°C for up to two days. Send by overnight first class post.
If possible, please complete the request form attached and send as a hard copy (do not send electronically) with the sample. This will ensure all relevant information is available and will aid us in processing your test.
PDF Request Form
Download Procollagen-3 N-Terminal Peptide (P3NP) Request Form
Turnaround Time
1 - 2 weeks
Price
Price available on application - please contact adrianturner1@nhs.net. Discounts could be available for significant workloads.
Contacts
Ms Tracy Dew
Tel: 020 3299 3726
e-mail: tracydew@nhs.net
or
Dr Hagosa Abraha
Tel: 020 3299 4134
e-mail: h.abraha@nhs.net
