The relationship between urine creatinine levels and statin use primarily involves monitoring for muscle-related toxicity, especially rhabdomyolysis, which is a rare but serious adverse effect of statins.

🔬 Understanding Creatinine:

• Creatinine is a waste product from the normal breakdown of muscle tissue.

• It's usually excreted in the urine through the kidneys.

• Urine creatinine levels help assess kidney function and muscle breakdown.

🧪 Statins and Urine Creatinine — The Connection:

🔺 1. Rhabdomyolysis Risk (Severe Muscle Breakdown)

One of the most dangerous side effects of statins is rhabdomyolysis, where damaged muscle fibers release myoglobin and creatine kinase (CK) into the bloodstream.

➡️ This overwhelms the kidneys and can lead to acute kidney injury (AKI).
➡️ Myoglobin is toxic to kidneys and can lower urine output and change urine color (dark, cola-colored).

🔍 Lab Findings in Rhabdomyolysis:

• Serum CK: 🚀 Elevated (often >10x normal)

• Urine myoglobin: Positive (reddish-brown urine)

• Urine creatinine:

  • May drop if kidneys are failing (due to damage)

  • Creatinine clearance (via 24-hour urine test) may decline

  • Urine creatinine-to-albumin ratio (UACR) is sometimes used to assess kidney involvement

🧠 Summary:

✅ Clinical Tip:

If a patient on statins presents with:

• Unexplained muscle pain or weakness

• Dark-colored urine

• Fatigue or reduced urine output

👉 Immediately check:

• Serum creatinine

• Creatine kinase (CK)

• Urinalysis (for myoglobin)

• Urine creatinine (to assess kidney filtration)