Why a normal creatinine result can miss early kidney damage

For people at higher risk of chronic kidney disease, eGFR alone may offer false reassurance. Pairing the blood test with a urine albumin-to-creatinine ratio can reveal early damage before kidney function falls.

A normal creatinine result can offer real reassurance, but it does not always tell the full story for people at higher risk of chronic kidney disease. In patients with diabetes, high blood pressure, cardiovascular disease, or a family history of kidney failure, a blood test that looks fine may still miss early damage if urine albumin has not been checked.

Creatinine is used to calculate estimated glomerular filtration rate, or eGFR, one of the main measures of how well the kidneys are filtering blood. Yet a preserved eGFR can exist alongside kidney injury. The urine albumin-to-creatinine ratio, known as uACR, looks for albumin, a protein that healthy kidneys normally keep out of the urine. When albumin begins to appear in urine, it can be an early warning sign even before kidney function declines.

That is why major guidance recommends pairing the two tests in at-risk people. The Kidney Disease: Improving Global Outcomes guideline published in 2024 advises assessing both filtration and urine albumin, while the American Diabetes Association’s 2026 standards recommend annual eGFR and uACR testing for people with type 2 diabetes and for those who have had type 1 diabetes for at least five years. Kidney organisations such as the National Kidney Foundation, Cleveland Clinic and the American Kidney Fund also describe uACR as a key tool for detecting early kidney damage and for estimating the risk of kidney failure and related cardiovascular complications.

The gap between what is recommended and what is actually done remains striking. An observational study published in 2022, drawing on data from 291,155 commercially insured and Medicare Advantage adults in the United States with laboratory-defined chronic kidney disease, found that 59% had no albuminuria measurement available in the study records. That does not prove the test was never done, but it does suggest that an important part of kidney risk assessment is often missing from the information available to clinicians.

The practical consequence is that “your kidney tests are normal” can be an oversimplification. A person may have a reassuring creatinine result and still have albumin spilling into the urine. For patients already known to be at elevated risk, the question should not be whether one number looks acceptable in isolation, but whether both filtration and urine albumin have been reviewed together.

At the same time, a single abnormal uACR result should not be treated as a diagnosis on its own. Albumin levels can rise temporarily after fever, infection or strenuous exercise, and chronic kidney disease generally requires evidence of persistent abnormality over at least three months. The point of testing is not to collect more laboratory values, but to clarify risk, guide blood pressure and medication decisions, and help determine whether closer monitoring or specialist referral is needed.

For patients, the most useful question may be straightforward: have both an eGFR blood test and a urine albumin test been done, and what do they show together? For clinicians, the more important step is to make sure the answer is clear before offering reassurance. In kidney disease, a normal blood test can be part of the picture without being the whole picture.