Creatinine

Routine annual

also cr

What it isCreatinine is a breakdown product of creatine, the energy-buffer molecule found in skeletal muscle. It is produced at a steady rate proportional to muscle mass and is cleared by the kidneys via glomerular filtration.

DoesActs as a workhorse marker of glomerular filtration; the kidneys must filter it continuously to keep blood levels stable.

GoodA stable mid-range creatinine relative to your muscle mass signals intact kidney filtration.

BadRising creatinine indicates failing kidney filtration. Very low creatinine in someone with normal kidneys often signals low muscle mass — a frailty signal.

Standard

Men 0.74–1.35 mg/dL; women 0.59–1.04 mg/dL.

Optimal

0.8–1.1 mg/dL men, 0.7–1.0 mg/dL women (narrow target)

Modifiers

Tracks muscle mass — bodybuilders run high without kidney disease; dehydration raises it transiently; high creatine supplementation raises it.

How to optimize

Lifestyle: Hydrate adequately, manage blood pressure, avoid chronic NSAIDs, Zone 2 cardio.
Diet: Moderate protein (not extreme); plenty of vegetables; lower sodium.
Supplements: Omega-3 EPA+DHA (2–4g/day), CoQ10 (100–200mg/day).
Peptides: —
Drugs: ACE inhibitors, ARBs, SGLT2 inhibitors protect kidney long-term.

within Kidney