Kidney function is often tracked using creatinine and eGFR. Many kidney issues have no symptoms early, so labs matter.
Quick summary
- eGFR estimates kidney filtering function (calculated from creatinine and other factors).
- Hydration, muscle mass, illness, and other factors can affect results.
- Trends over time matter.
What can affect results
- Dehydration or recent illness
- Muscle mass and heavy exercise
- Certain substances or supplements
- Long-term conditions like diabetes or high blood pressure
When to follow up
- New abnormal results or rising creatinine trend
- Protein in urine
- Swelling, decreased urination
- Persistent vomiting/diarrhea
Electrolytes (potassium/sodium)
- Abnormal potassium or sodium levels can be important and should be reviewed promptly in the right clinical context.
Next step
More resources: Kidney & Electrolytes. Book an in-person visit to review abnormal kidney labs, possible causes, and the appropriate next steps.
Last reviewed: April 8, 2026