Creatine is a dietary supplement of a compound the body makes and obtains from meat and fish, taken to build and preserve muscle, strength and brain function. At a few grams daily alongside resistance training it reliably adds modest muscle and strength and improves repeated hard efforts. Without training, most of what it adds is water. Memory gains appear mainly in older adults. Safety at ordinary doses is reassuring. (Full Review)
| Marker | Target | Why |
|---|---|---|
| Serum creatinine | 0.6–1.0 mg/dL (women), 0.7–1.1 mg/dL (men) | Detects the expected supplement artefact and any real change |
| Cystatin C | 0.60–0.95 mg/L | Kidney filtration marker unaffected by creatine or muscle mass |
| eGFR | Above 90 mL/min/1.73 m² | Tracks true filtration capacity over years |
| BUN | 10–16 mg/dL | Second-line kidney and protein-turnover check |
| HbA1c | Below 5.4% | Captures the glucose-disposal benefit reported with training |
| Fasting glucose | 75–86 mg/dL | Early signal of the metabolic effect before HbA1c moves |
| ALT | 10–26 U/L | Confirms no liver strain, the second most common unfounded concern |
| Body weight | Rise of 0.5–1.5 kg in the first 2 weeks, then stable | Distinguishes expected water retention from fat gain |
| Lean body mass | No established target; track change from own baseline | The primary outcome creatine is taken for |
| Grip strength | Track change from own baseline; below 27 kg (men) or 16 kg (women) marks clinical weakness | Cheap, validated proxy for whole-body strength and function |
| Blood pressure | Below 120/80 mmHg | Confirms fluid shift is not raising pressure |
Cadence: Body weight weekly for the first month; kidney and liver panel at 3 months, then every 6–12 months; body composition and strength benchmarks at 3 months, then annually; every 3–6 months where kidney function is reduced or medication is kidney-cleared