Why is a Kidney Biopsy Needed?
May 5, 2026
Why is a Kidney Biopsy Needed? A kidney biopsy is a specialised medical procedure where a tiny piece of kidney tissue is removed for examination under a microscope. Whilsy many people worry when they ...
Understanding your kidney lab results can be overwhelming. Most kidney issues are “silent,” meaning you won’t feel symptoms until your function is quite low. Regular monitoring of blood and urine is the only way to catch Chronic Kidney Disease (CKD) early.
If your eGFR (estimated Glomerular Filtration Rate) is consistently under 60 mL/min, you may have CKD and should monitor the following markers closely.
| Test | What it Measures | Normal Range | When to See a Doctor (Action Level) |
| eGFR | Overall filtration power | 90–120 mL/min | < 60: Refer to specialist; < 15: Urgent |
| Creatinine | Muscle waste in blood | < 120 µmol/L | > 200 or rising rapidly |
| Urine ACR | Protein (Albumin) leak | < 3 mg/mmol | > 30: Indicates kidney damage |
| Potassium (K) | Heart/Muscle function | 3.5–5.3 mmol/L | < 3.0 or > 6.0: Emergency |
| Sodium (Na) | Fluid/Salt balance | 135–145 mmol/L | < 130 or > 150: Urgent |
| Urea | Protein waste | 3–7 mmol/L | > 15: Kidney function is struggling |
| Bicarbonate | Blood acidity | 22–28 mmol/L | < 18: Risk of metabolic acidosis |
| Haemoglobin | Oxygen in blood | 110–170 g/L | < 100: Indicates CKD-related anaemia |
| Calcium | Bone health | 2.2–2.6 mmol/L | < 1.8 or > 3.0: Urgent |
| Phosphate | Mineral balance | 0.8–1.4 mmol/L | > 2.0: Risk of bone disease |
Not every “abnormal” result requires an emergency room visit. Use this guide to determine your next steps:
🚨 Emergency (Call 999 or attend A&E)
Potassium > 6.0 mmol/L: High potassium can cause sudden, fatal heart rhythm changes.
eGFR < 15 mL/min: This indicates Stage 5 Kidney Failure; immediate specialist intervention is required.
⚠️ Urgent (Contact your GP/Doctor the same day)
Sodium < 130 or > 150: Can lead to confusion or seizures.
Calcium < 1.8 or > 3.0: Can cause severe muscle issues or heart problems.
📅 See Doctor Soon (Book an appointment within days/weeks)
Rising Creatinine: If your level is steadily increasing, your CKD may be progressing.
Urine ACR > 30: High protein leakage significantly increases the risk of heart disease and kidney failure.
Haemoglobin < 100: You may need iron supplements or EPO (Erythropoietin) injections.
The Heart Connection: Kidney health and heart health are linked. High cholesterol (> 6.0) or high blood sugar (Glucose > 7) puts extra strain on your kidneys.
Bone Health: If your Phosphate is high or Bicarbonate is low, your body may be pulling minerals from your bones to balance your blood, leading to “Renal Bone Disease.”
The “Silent” Factor: You can lose 50% of your kidney function and still feel perfectly fine. This is why the eGFR and Urine ACR tests are vital—they see what you cannot feel.
Are you hydrated? Dehydration can falsely worsen your results.
Are the results stable? A single bad result is less concerning than a “downward trend.”
Is your blood pressure controlled? High BP is the #1 cause of worsening kidney numbers.
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