Thread by @Rheumat_Aravind

🧵 How to Work Up a Suspected Connective Tissue Disease (CTD) in 15 Minutes

CTDs are complex, systemic, and often subtle.
A smart, stepwise approach saves time—and organs.
Let’s simplify the workup 👇
#Rheumatology #MedTwitter #Autoimmune

1/
🧍‍♀️ Step 1: Pattern Recognition
Start with syndromic clues:
🔹 Arthritis + rash → SLE
🔹 Raynaud + skin thickening → SSc
🔹 Sicca + parotid swelling → Sjögren’s
🔹 Proximal weakness + rash → Myositis
🔹 Inflammatory back pain + uveitis → SpA

✅ Clinical suspicion comes before antibody panels.

2/
📝 Step 2: Symptom Checklist (ROS)
Always ask about:
✔️ Fatigue, fever, weight loss
✔️ Photosensitivity, oral/nasal ulcers
✔️ Hair loss, rashes
✔️ Raynaud’s, digital ulcers
✔️ Dry eyes/mouth
✔️ Chest pain (pleuritis, pericarditis)
✔️ Dyspnea, hematuria
✔️ Neurologic symptoms
✔️ Arthralgia/arthritis
✔️ Muscle weakness

✅ Helps focus testing.

3/
🔬 Step 3: First-Line Labs
✔️ CBC, ESR, CRP
✔️ Creatinine, urine routine ± UPCR
✔️ AST/ALT, albumin
✔️ ANA (preferably IIF method)
✔️ RF if joint symptoms
✔️ C3, C4
📌 Ferritin if systemic symptoms or cytopenia

⚠️ Avoid shotgun ENAs on Day 1 unless suspicion is strong

4/
🧪 Step 4: Reflex Serology Based on Suspicion or ANA+
🔹 dsDNA, Sm → SLE
🔹 Ro/La → Sjögren’s, subacute cutaneous lupus
🔹 Scl-70, centromere → SSc
🔹 RNP → MCTD
🔹 Jo-1, Mi-2, TIF-1γ → Myositis
🔹 APL panel (LA, aCL, anti-β2 GP1) → APS

✅ ANA alone is not diagnostic—it must match the clinical picture.

5/
📷 Step 5: Imaging If Symptoms Guide You
🔸 CXR or HRCT → cough, crackles, ILD
🔸 MRI thigh → myositis suspicion
🔸 Echo → dyspnea, pericarditis
🔸 X-rays hands/SI → erosions, sacroiliitis
🔸 Nailfold capillaroscopy → Raynaud’s

✅ Imaging reveals subclinical organ involvement

6/
🧪 Step 6: Rule Out Mimics Before Calling It CTD
✔️ Infections (HIV, TB, hepatitis B/C, parvo)
✔️ Drug-induced lupus (hydralazine, INH, etc.)
✔️ Malignancy (cytopenia, weight loss)
✔️ Thyroid, B12/D deficiency
✔️ Fibromyalgia

⚠️ Avoid mislabeling functional or reactive illnesses as autoimmune

7/
🧠 Step 7: Evaluate Organ Involvement
🎯 Renal → proteinuria, RBC casts
🎯 Lung → crackles, dyspnea → HRCT
🎯 Skin → vasculitis, photosensitive rash
🎯 Neuro → seizures, mononeuritis
🎯 Hematologic → pancytopenia, Coombs+
📌 Do urine exam in all suspected SLE patients!

8/
📌 Final Rules
✔️ Don’t order everything—order intentionally
✔️ ANA ≥1:160 + clinical signs = worth pursuing
✔️ Don’t chase low-titer ANA in isolation
✔️ Don’t forget vaccination, infection screen, and family history

✅ CTD workup = smart history + targeted labs + context

💡 Smart medicine starts with questions, not test panels.

Clinical suspicion → focused testing → confirm pattern → refer/treat.

🔁 Share to help juniors demystify CTD workup
#RheumTwitter #Autoimmune #SLE #ClinicalReasoning #MedEd

@DrAkhilX @IhabFathiSulima