Non-radiographic axial spondyloarthritis of lumbar region

This code represents a chronic inflammatory arthritis primarily affecting the spine and sacroiliac joints in the lumbar region, where definitive radiographic evidence of sacroiliitis is absent. Patients typically present with inflammatory back pain, stiffness, and functional limitations, but imaging studies like X-rays do not show the characteristic structural damage seen in ankylosing spondylitis.

Use this code for patients diagnosed with non-radiographic axial spondyloarthritis (nr-AxSpA) specifically affecting the lumbar spine. Documentation should clearly indicate inflammatory back pain, negative or inconclusive X-ray findings for sacroiliitis, and often positive MRI findings or elevated inflammatory markers supporting the diagnosis.

• Ensure documentation explicitly states "non-radiographic" and specifies the "lumbar region" to support this granular code.
• Differentiate from M45.A0 (non-radiographic axial spondyloarthritis, unspecified site) when the lumbar region is clearly identified.
• Consider sequencing with codes for associated symptoms (e.g., inflammatory back pain) or related conditions (e.g., enthesitis, uveitis) if present.