Alanine aminopeptidase, γ-glutamyl transferase and β2-microglobulin as diagnostic markers in patients with rheumatoid arthritis

Abstract

The purpose of this research is to evaluate the values of alanine aminopeptidase (AAP), γ-glutamyl transferase (γ-GT), and β2-Microglobulin in urine (β2-M), in untreated rheumatoid arthritis (RA) and to define the effect of untreated rheumatoid arthritis on the tubular function and brush border region. We used a kinetic assay for AAP, standard methods by the IFCC for γ-glutamyl transferase and MEIA for the determination of β2-Microglobulin in urine in 70 participants (35 untreated RA patients, 35 healthy individuals). From the total of 35 RA patients, 24 patients had AAP (sensitivity of the test 68.57%), 16 patients had γ-GT enzymuria (sensitivity of the test 45.71%), while the presence of β2-Microglobulin in urine was found in a very low percentage. Out of 18 RF negative patients, 14 patients are AAP positive, 10 patients were γ-GT positive, while the presence of β2-Microglobulin in urine was not detected. Among 17 RF positive RA patients, the presence of AAP was noticed in 10, the presence of γ-GT in 6 patients, while the presence of β2-Microglobulin in urine was not detected. AAP has higher sensitivity than γ-GT and β2-Microglobulin in the detection of asymptomatic renal lesions in untreated RA.

Keywords

• alanine aminopeptidase
• γ-glutamyl transferase
• β2-microglobulin
• rheumatoid arthritis
• rheumatoid factor