26th May 2025

A 29-year-old male presents with a 3-month history of progressive back pain and stiffness.

A 29-year-old male presents with a 3-month history of progressive back pain and stiffness. He describes the pain as being worse first thing in the morning, with some improvement throughout the day and with exercise. He is otherwise well, but is currently being investigated for persistent loose stools and rectal bleeding. His mother has a history of psoriatic arthritis. On examination, he has reduced forward flexion of the spine. Blood test results showed the following:

• Hb 120 g/L (130-180)
• MCV 92fL (80-96)
• WCC 5.0 x 10⁹/L (4.0-11.0)
• CRP 32 mg/L (<10)
• Sodium 138 (133–146 mmol/L)
• Potassium 4.9 (3.5–5.3 mmol/L)
• Creatinine 68 (45–84 μmol/ L)
• EGFR >90 
• Serum iron 12 (11.6 – 35.0 μmol/​L)
• Serum b12 150 (180 – 1000 pg/mL)
• Serum folate 3.2 (> 4.0 ng/mL)
• ESR 3
• LFTs normal 
• Rheumatoid factor 8 (0-20 u/mL)
• Anti-CCP negative 
• Stool MC&S: negative

A spinal x-ray is performed, which shows the presence of right-sided sacroiliitis. 

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