Complete kidney function test panel
| Test | Normal Range | What it measures |
|---|---|---|
| Creatinine | Men: 0.74–1.35 mg/dL; Women: 0.59–1.04 mg/dL | Waste product from muscle — rises as kidneys fail |
| eGFR | ≥60 mL/min/1.73m² | Estimated kidney filtering rate — most important kidney measure |
| Blood Urea / BUN | 7–20 mg/dL | Protein waste product — also raised in dehydration and bleeding |
| Uric Acid | Men: 3.5–7.2 mg/dL; Women: 2.6–6.0 mg/dL | Gout risk — also rises in kidney disease |
| Sodium | 136–145 mEq/L | Fluid balance — regulated by kidneys |
| Potassium | 3.5–5.0 mEq/L | Critical electrolyte — dangerously high in kidney failure |
| Bicarbonate | 22–29 mEq/L | Acid-base balance — low in CKD (metabolic acidosis) |
| Phosphorus | 2.5–4.5 mg/dL | Rises in CKD — causes bone disease |
| Calcium | 8.5–10.5 mg/dL | Bone and parathyroid — affected in CKD |
| Urine ACR | <30 mg/g | Kidney protein leakage — earliest sign of damage |
Why eGFR matters more than creatinine
The problem with creatinine alone
Creatinine depends on muscle mass — a young muscular man and an elderly frail woman with the same creatinine have vastly different kidney function. eGFR (estimated GFR) corrects for age, sex and race to give a more accurate kidney function estimate. eGFR below 60 on two tests at least 3 months apart = chronic kidney disease. eGFR can appear falsely normal even when significant kidney damage has occurred — urine ACR (protein test) is needed to detect early kidney disease when eGFR is still above 60.
Why potassium is critical in kidney disease
Healthy kidneys excrete excess potassium in urine. As kidneys fail, potassium accumulates in the blood (hyperkalaemia). Potassium above 6.0 mEq/L causes dangerous heart arrhythmias and can be fatal. People with CKD need to monitor potassium regularly and may need to limit high-potassium foods (bananas, potatoes, tomatoes, oranges) and avoid medications that raise potassium (ACE inhibitors, ARBs, potassium-sparing diuretics).
Questions to ask your kidney doctor
- What is my eGFR stage, and how quickly is it declining?
- Do I have significant proteinuria on my urine ACR?
- Is my potassium safe?
- Do I need dietary restrictions for my kidney disease?
- Am I on any medications that could harm my kidneys?