Last reviewed by Dr. Leena Joshi, MD, August 2026
Kidney lab results come down to four numbers: eGFR (how well your kidneys filter), creatinine (a waste product that rises when filtering drops), BUN (a second waste product), and urine ACR (how much albumin is leaking into the urine). An eGFR under 60 or an ACR of 30 mg/g or higher, on more than one test, is the usual signal to see a nephrologist. Dr. Leena Joshi, MD reviews these results with patients in Burlingame and Daly City and explains what each one means for you. Call (650) 355-5551.
What do the four main kidney tests mean?
| Test | What it measures | Typical reference range (adults) | What a result outside the range can mean |
|---|---|---|---|
| eGFR (estimated glomerular filtration rate) | How much blood the kidneys filter per minute, calculated from creatinine, age, and sex | 90 or higher normal; 60 to 89 mildly reduced; below 60 for 3+ months meets the definition of CKD | Lower numbers mean less filtering. Below 60 on two tests three months apart is chronic kidney disease. |
| Serum creatinine | A waste product from muscle that the kidneys clear | Roughly 0.6 to 1.3 mg/dL; varies by lab, sex, and muscle mass | Higher values suggest reduced filtering, dehydration, or a medication effect. Read with eGFR. |
| BUN (blood urea nitrogen) | A waste product from protein breakdown | Roughly 7 to 20 mg/dL; varies by lab | High with normal creatinine often means dehydration or high protein intake; high with high creatinine points to the kidneys. |
| Urine ACR (albumin-to-creatinine ratio) | How much albumin leaks into the urine | Below 30 mg/g normal; 30 to 300 moderately increased; above 300 severely increased | 30 or higher on two tests is albuminuria, an early sign of kidney damage, common in diabetes and high blood pressure. |
Reference ranges vary by laboratory. Use the range printed on your own report, and let Dr. Joshi interpret the pattern across tests rather than one value.
How do doctors use these numbers together?
eGFR sets the stage of kidney function; ACR shows whether damage is present even when eGFR looks fine. Diabetes and high blood pressure often show up as a rising ACR first. Creatinine and BUN add context: both high suggests the kidneys; BUN high alone suggests dehydration or diet. Dr. Joshi also looks at the trend over time. One low eGFR after a stomach virus is different from a slow decline over two years.
When do kidney lab results mean you should see a nephrologist?
- eGFR below 60 on two tests at least three months apart, or falling year over year
- ACR of 30 mg/g or higher on two tests
- Rising creatinine without a clear short-term cause
- Abnormal kidney labs plus diabetes or high blood pressure
- Blood in the urine that is not explained by infection or stones
What will Dr. Joshi do with your results?
She reviews your history and medications, repeats or adds tests to confirm the finding and find the cause, and tells you your stage in plain language. Then she sets a plan: blood pressure and blood sugar targets, kidney-protective medicines where they fit, diet matched to your labs, and a monitoring schedule so changes are caught early. She sends her notes to your primary care doctor after each visit.
Related reading: when to see a nephrologist, chronic kidney disease treatment, and protein in the urine (proteinuria).
Frequently asked questions
What is a normal eGFR?
90 or higher is normal for most adults, though eGFR declines slowly with age. 60 to 89 is mildly reduced and needs context. Below 60 for three months or longer meets the definition of chronic kidney disease.
What does high creatinine mean?
Creatinine is a waste product from muscle. When the kidneys filter less, creatinine rises. It also runs higher in people with more muscle mass and after dehydration or certain medications, so Dr. Joshi reads it alongside eGFR and your history.
What is the ACR test and why does it matter?
The urine albumin-to-creatinine ratio measures how much albumin is leaking into the urine. 30 mg/g or higher, on two tests, is albuminuria, an early sign of kidney damage that can appear before eGFR falls.
What is the BUN to creatinine ratio?
It compares two waste products. A high ratio often points to dehydration or bleeding in the gut rather than kidney disease itself; a normal ratio with both values high points to the kidneys. Dr. Joshi uses it as context, not as a diagnosis on its own.
How often should kidney labs be checked?
At least yearly if you have diabetes, high blood pressure, or a family history of kidney disease; every 3 to 6 months if you have known kidney disease. Dr. Joshi sets the schedule by your stage.
Can kidney lab results improve?
Yes when the cause is temporary: dehydration, a medication effect, or a recent illness. Lasting damage usually does not reverse, but treatment can stop the numbers from getting worse.
Schedule an appointment
Dr. Leena Joshi, MD is a board-certified nephrologist with offices at 1750 El Camino Real, Suite 301, Burlingame and 1800 Sullivan Ave, Suite 507, Daly City. New patient appointments are typically available within days. A referral from your doctor is required; visits are by appointment only. Call (650) 355-5551.
This page is for general education and is not a substitute for medical advice. Always consult your physician about your specific situation.
Medically reviewed by Leena Joshi, MD.