A
Here’s a quick clinical breakdown tying those together — Tubulointerstitial Nephritis (TIN), methylprednisolone treatment, and protein:creatinine ratio (PCR):
🧠 Tubulointerstitial Nephritis (TIN)
🔍 Definition:
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Inflammation of the renal tubules and interstitium
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Often sparing the glomeruli
🧾 Causes:
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Drugs (most common): NSAIDs, antibiotics (penicillins, cephalosporins, rifampin), PPIs
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Infections (e.g., EBV, mycoplasma)
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Autoimmune: SLE, Sjögren, TINU syndrome (Tubulointerstitial Nephritis and Uveitis)
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Idiopathic
🧪 Key Labs:
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Urinalysis: sterile pyuria, WBCs, WBC casts, mild proteinuria
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Eosinophiluria (in drug-induced)
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Elevated creatinine
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Sometimes hypokalemia, metabolic acidosis (RTA type 1 or 2)
💊 Methylprednisolone in TIN
When to use:
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For moderate to severe TIN, especially if:
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AKI is worsening
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Autoimmune or TINU suspected
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No response to drug withdrawal
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IV pulse methylprednisolone (e.g., 10–30 mg/kg/day for 3–5 days) → then oral pred taper
Goal:
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Reduce inflammation
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Preserve long-term renal function
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Prevent progression to chronic kidney disease (CKD)
💧 Urine Protein:Creatinine Ratio (uPCR)
🔬 Role in TIN:
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TIN typically causes low-grade proteinuria (tubular pattern)
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PCR <0.5 is common (reflects tubular dysfunction rather than glomerular damage)
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If PCR is elevated (>1):
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Consider coexisting glomerular pathology
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Or progression to more significant renal damage
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🧮 Interpretation (in mg/mg):
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<0.2 = Normal
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0.2–2 = Tubular or mild proteinuria
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2 = Suggests glomerular origin
💡 Summary Pearl:
"TIN typically presents with sterile pyuria, low-grade proteinuria, and AKI. Methylprednisolone is used when inflammation threatens long-term renal function. A rising urine PCR may signal evolving glomerular involvement or worsening disease."
Would you like an infographic pearl on this for your WhatsApp series? I can tailor it as a quick-reference card.
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