The Role of P1NP Measurement for Children with Juvenile Idiopathic Arthritis

Introduction: Type I collagen with N-terminal propeptides (PINP) is used to investigate bone formation in adult especially due to cancer disorders, but a lack of appropriate reference data has hampered use of P1NP in pediatrics.

Aim: Our aim was to determine the importance of P1NP for patients with Juvenile Idiopathic Arthritis (JIA).

Materials and methods: The study included 10 patients with JIA within 9 – 18 years old, there were 60% of female and 40 % of male. Assessment of children was based on physical, laboratory examination and instrumental tests. ECLIA method was used for the measurement of P1NP. For statistic processing of the material Stagraphics 3.0 and Student-Fischer test were done.

Results: Investigated patients had JIA, there were 50% of children with poliarthritis and negative rheumatoid factor (RF); 20 % of patients had poliarthritis with positive RF; another 20 % of cases were classified as oligoarticular form and 10 % - enthesitis-related arthritis. Disease duration ranged within 8 to 96 months. All patients has been treated with “basic” therapy, such as NSAID, its average duration of taking was (56.00±39.19) months; average duration of Methotrexate taking was (21.00±35.94) months. Some patients were treated with immunobiological preparation during (1.67±2.25) months. Despite treatment radiological changes III degree by Steinbrocker score in 50 % of cases and IV degree in 30 % of kids were determined. The rate of P1NP depended on age and gender; 77.8 % of patients represented normal range of P1NP, 11.1 % - with increased and 11.1 % of kids had decreased level of P1NP. The mean level of P1NP was ((378.78±370.80) ɲg/ml), serum calcium - (2.34±0.07) mmol/L and phosphorus (1.58±0.36) mmol/L, which were within normal range.

Conclusion: Measurement of P1NP is not sensitive for determination of osteoporosis in children with JIA.