Morning stiffness in a 58-year-old with normal acute-phase markers
A 58-year-old woman presents with 9 months of bilateral hand pain. Morning stiffness lasts 90 minutes and improves with activity. Examination shows soft swelling of the MCP and PIP joints of both hands, a positive squeeze test across the MCP rows, and no DIP involvement. There are no rheumatoid nodules. Laboratory tests: CRP 4 mg/L (normal <5), ESR 12 mm/h, RF negative, anti-CCP negative, haemoglobin 128 g/L, ferritin normal. Hand radiographs show no erosions but mild periarticular osteopenia. She has hypertension and a history of treated pulmonary tuberculosis 20 years ago. She asks whether she has rheumatoid arthritis and whether she can start methotrexate today.
1. How should the clinician interpret the normal CRP, ESR, RF and anti-CCP results in the context of this presentation? What is the most likely diagnosis and what differential remains?
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Normal acute-phase markers and negative autoantibodies do not exclude inflammatory arthritis. Up to 30-40% of patients with early rheumatoid arthritis have normal CRP and ESR, and seronegative disease is well recognised, particularly in older-onset and smouldering presentations.
The clinical pattern is the strongest evidence: symmetrical small-joint synovitis, MCP/PIP distribution, prolonged morning stiffness and a positive MCP squeeze test all point to an inflammatory polyarthritis. The most likely diagnosis is seronegative rheumatoid arthritis or an early undifferentiated inflammatory arthritis that may evolve.
Differentials to keep active:
- Psoriatic arthritis - ask specifically about psoriasis, nail pitting, dactylitis, enthesitis; DIP sparing does not exclude it.
- Polymyalgia rheumatica / RS3PE - usually older, prominent shoulder/hip girdle involvement, dramatic response to low-dose steroids.
- Crystal arthropathy - usually episodic and mono/oligoarticular, but can mimic; consider ultrasound for double contour or synovial CPPD.
- Viral or paraneoplastic arthritis - consider if systemic features appear.
Ultrasound or MRI of the hands can demonstrate synovitis and tenosynovitis even when radiographs are normal, and should be used to support the diagnosis rather than to rule it out.
2. Assuming a diagnosis of rheumatoid arthritis is confirmed, outline your treatment plan, including the specific issue raised by her tuberculosis history.
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Step 1 - Baseline workup before DMARDs: full blood count, liver and renal function, hepatitis B and C serology, HIV where relevant, and latent tuberculosis screening (interferon-gamma release assay and chest radiograph). Her prior treated TB makes this mandatory before any biologic or JAK inhibitor and is prudent before methotrexate.
Step 2 - First-line therapy: methotrexate is the anchor drug, started at 10-15 mg once weekly orally or subcutaneously, escalating to 20-25 mg weekly as tolerated, with folic acid 5 mg weekly on a non-methotrexate day. Counsel on weekly (not daily) dosing, alcohol limits, teratogenicity and the need for contraception if relevant. Check FBC, ALT and creatinine at baseline, 2-4 weeks, then every 3-6 months once stable.
Step 3 - Bridging: short-course low-dose prednisolone (e.g. 10 mg daily tapering over 8-12 weeks) or an intra-articular depot steroid can control symptoms while methotrexate takes effect. If latent TB is confirmed, complete chemoprophylaxis before starting steroids at higher doses or biologics.
Step 4 - Escalation: at 3-6 months, if the target (remission or low disease activity by DAS28 or CDAI) is not met, add a second conventional DMARD (hydroxychloroquine, sulfasalazine, leflunomide) or move to a TNF inhibitor or other biologic. Any biologic or JAK inhibitor requires documented latent TB screening and treatment, and she should be monitored for TB reactivation.