Patient Guide

Kidney Health Tests: Complete Guide

Q: Which tests show how well my kidneys work?

Creatinine and the calculated eGFR are the core measures of kidney function, while an urine albumin:creatinine ratio (ACR) detects early kidney damage before function declines.

Q: What is eGFR and what's a normal value?

eGFR estimates how well the kidneys filter blood. Above 90 is generally normal, while values below 60 for more than three months indicate chronic kidney disease.

Q: Can kidney damage be present with normal blood tests?

Yes. Early kidney damage often shows first as protein (albumin) leaking into the urine, which is why the urine ACR test is important alongside blood tests, especially in diabetes and high blood pressure.

Chronic kidney disease often has no symptoms until kidneys are significantly damaged. These blood and urine tests catch problems early: when treatment works best.¹

Written by Suman Konda, PharmD, Clinical Pharmacist · Editorial policy · Not medical advice

Last updated: 01 August 2026 · How we check our content

The complete kidney test panel

Test	Normal	What it checks
Serum Creatinine	Men: 0.74–1.35 mg/dL; Women: 0.59–1.04 mg/dL	Kidney filtering efficiency
eGFR	>90 mL/min	% of kidney function remaining
Blood Urea Nitrogen (BUN)	7–20 mg/dL	Protein waste in blood
BUN:Creatinine Ratio	10:1 – 20:1	Dehydration vs kidney damage
Urine Routine	No protein, no RBC	Kidney leakage
Urine Microalbumin	<30 mg/g creatinine	Earliest sign of kidney damage
Serum Electrolytes	Na 136–145, K 3.5–5.0 mEq/L	Fluid and salt balance
Uric Acid	Men: 3.5–7.2 mg/dL; Women: 2.6–6.0 mg/dL	Gout and kidney stones risk

Who should get regular kidney tests?

Diabetics: diabetes is the leading cause of kidney failure worldwide. Annual creatinine + urine microalbumin from diagnosis
Hypertensives: high blood pressure is the second leading cause. Annual KFT
People taking NSAIDs regularly: ibuprofen, diclofenac, naproxen all damage kidneys with prolonged use
People taking contrast dye for CT scans: contrast nephropathy risk
Anyone with recurrent kidney stones: 24-hour urine study + metabolic workup
Family history of kidney disease: polycystic kidney disease is hereditary

The most important early warning sign: urine microalbumin

Microalbuminuria: catch kidney damage years early

Normal kidneys do not let albumin (a large protein) escape into urine. The earliest sign of diabetic or hypertensive kidney damage is tiny amounts of albumin leaking through (microalbuminuria: 30–300 mg/g creatinine). This is detectable years before creatinine rises or eGFR drops. At the microalbuminuria stage, kidney damage is almost completely reversible with tight blood pressure and sugar control. Once creatinine rises significantly, damage is mostly irreversible, which is why early testing matters so much.

Questions to ask your doctor

What is my eGFR, and what does that mean for my kidney function percentage?
Should I test urine microalbumin given my diabetes/hypertension?
Which pain medications are safe for me to take?
Do I need a kidney ultrasound?

Frequently Asked Questions

Which tests show how well my kidneys work?

Creatinine and the calculated eGFR are the core measures of kidney function, while an urine albumin:creatinine ratio (ACR) detects early kidney damage before function declines.

What is eGFR and what's a normal value?

eGFR estimates how well the kidneys filter blood. Above 90 is generally normal, while values below 60 for more than three months indicate chronic kidney disease.

Can kidney damage be present with normal blood tests?

Yes. Early kidney damage often shows first as protein (albumin) leaking into the urine, which is why the urine ACR test is important alongside blood tests, especially in diabetes and high blood pressure.

References

Sources cited on this page. PubMed links open the original abstract.

Levey AS, Coresh J. Chronic kidney disease. Lancet. 2012;379(9811):165–180. PMID 21840587 · doi:10.1016/S0140-6736(11)60178-5

eGFR – what the number means and how it's calculated

Estimated glomerular filtration rate (eGFR) is the standard measure of overall kidney function. It estimates how much blood the kidneys filter per minute, per 1.73 m² of body surface area. The two main equations used in the UK:

CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration): Uses serum creatinine, age, and sex. More accurate at eGFR above 60 than the older MDRD equation. Replaced MDRD as the UK standard in 2021.
CKD-EPI with cystatin C: More accurate in patients where creatinine is unreliable – particularly very muscular athletes (overestimates kidney function with creatinine alone) or cachexic/elderly patients (underestimates impairment). NICE recommends cystatin C-based eGFR when creatinine-based results seem inconsistent with clinical status.

CKD staging by eGFR (alongside urine ACR): G1 ≥ 90, G2 60–89, G3a 45–59, G3b 30–44, G4 15–29, G5 below 15 (kidney failure – usually requiring renal replacement therapy). A diagnosis of CKD requires the eGFR abnormality to persist for more than 3 months.

Urine tests – albumin and protein leakage

Blood tests measure what the kidney fails to remove; urine tests measure what it fails to retain:

Urine albumin-to-creatinine ratio (ACR): The primary urine test for detecting early kidney damage. Even small amounts of albumin in urine (microalbuminuria, ACR 3–30 mg/mmol) indicate glomerular damage – seen earliest in diabetic nephropathy, hypertensive kidney disease, and lupus nephritis. ACR above 30 mg/mmol = macroalbuminuria (significant proteinuria). First morning urine gives the most reproducible result. ACR classifies albuminuria: A1 (below 3), A2 (3–30), A3 (above 30).
Urine protein-to-creatinine ratio (PCR): Measures all urinary proteins (not just albumin). PCR above 100–150 mg/mmol indicates clinically significant proteinuria warranting nephrology review. Nephrotic syndrome (PCR above 350 mg/mmol, hypoalbuminaemia, oedema) is a medical emergency requiring urgent renal biopsy to determine cause (minimal change disease, focal segmental glomerulosclerosis, membranous nephropathy).
Urine microscopy: Red cell casts in urine (red blood cells trapped in protein cylinders) are virtually pathognomonic of glomerulonephritis – an inflammatory kidney condition requiring urgent immunosuppression. White cell casts indicate pyelonephritis (kidney infection) rather than bladder infection.