Renal failure causes decreased creatinine clearance.

Creatinine clearance is a marker of glomerular filtration rate (GFR). In renal failure, nephron function declines, so the kidneys filter and clear creatinine from the blood less effectively. This leads to:

This inverse relationship is confirmed across multiple sources - for example, Smith and Tanagho's General Urology notes that "serum creatinine and blood urea nitrogen levels and creatinine clearance are the best indicators of the extent of renal failure" (elevated serum creatinine, reduced clearance), and Mulholland and Greenfield's Surgery describes acute kidney injury patients presenting with "oliguria and decreased creatinine clearance."

Caveat in acute renal failure: Henry's Clinical Diagnosis and Management by Laboratory Methods notes that during acute renal failure, serum creatinine rises rapidly as clearance falls, and then falls rapidly during recovery - so a single spot creatinine clearance measurement can be misleading in the acute (non-steady-state) setting, since the calculation assumes steady-state creatinine production and excretion.