A kidney function test groups blood and urine results that reflect how the kidneys filter and what they let through. Creatinine and eGFR describe filtration, urea adds context, uric acid answers a different question, and a urine albumin-to-creatinine ratio describes albumin loss. The report's printed range decides what is flagged.
The panel is a mixture of measured and calculated lines, and it draws on two sample types. Reading it well means knowing which line came from where, and which lines are derived from the others.
What the panel measures
Most of the lines come from a blood sample, and one comes from urine. The blood lines describe the concentration of substances the kidneys clear, which gives an indirect view of clearance. The urine line describes how much albumin is escaping into urine, corrected for how concentrated the sample is.
Creatinine is a waste product of muscle metabolism, produced at a fairly steady rate and cleared by the kidneys. Its blood concentration reflects the balance between production and clearance. eGFR is calculated from creatinine together with age and sex, and sometimes other factors, to estimate how much blood the kidneys filter per minute. It is an estimate, not a direct measurement of filtration.
Urea is another waste product, produced when protein is broken down. Uric acid comes from purine breakdown and is handled by the kidneys, but it is not a filtration marker. UACR compares urine albumin with urine creatinine in the same sample, which is how the report corrects for how dilute the urine is.
The tests inside it
| Test | Also printed as | Unit | What it reflects |
|---|---|---|---|
| Creatinine | Creat, Cr, serum creatinine | mg/dL, umol/L | A waste product of muscle metabolism cleared by the kidneys, and the main input to eGFR. |
| eGFR | Estimated glomerular filtration rate, eGFR-CKD-EPI | mL/min/1.73 m2 | A calculated estimate of how much blood the kidneys filter per minute, indexed to body surface area. |
| Urea | BUN, blood urea nitrogen, urea | mg/dL as BUN, mmol/L as urea | A waste product of protein breakdown, affected by hydration and protein intake. |
| Uric acid | Urate, serum uric acid | mg/dL, umol/L | A product of purine breakdown, handled by the kidneys but not a filtration marker. |
| Urine albumin-to-creatinine ratio | UACR, ACR, microalbumin/creatinine | mg/g, mg/mmol | The ratio of albumin to creatinine in a urine sample, reflecting albumin loss in urine. |
Some reports also print a urine albumin concentration and a urine creatinine value as separate lines. The ratio is calculated from those two numbers. eGFR may be printed in more than one form, and the unit tells you which one you are reading.
Why this page does not print a range
Kidney reference ranges depend on the laboratory, the assay, and the population. Creatinine values differ by sex and by muscle mass, and some laboratories print age-specific ranges. eGFR may be reported with a note about the equation used, and equations are revised from time to time. UACR ranges can depend on the sample and on how the urine was collected.
The range printed on the report that produced your value is the one that applies. Doctano keeps that printed range with the result and does not replace it with a general range from the internet. For eGFR, read the equation and the unit printed on the report alongside the number, because the same number can be produced by different equations.
What moves together
Creatinine is read with eGFR, and the two move in opposite directions. Creatinine is measured; eGFR is calculated from it, with age, sex, and sometimes other variables, so a higher creatinine usually produces a lower eGFR. Because eGFR is derived, it inherits the limits of creatinine. Muscle mass, recent strenuous exercise, and some medicines can affect creatinine without a change in filtration, and the estimate is less reliable at the extremes of body size and in people whose muscle mass is unusual for their age and sex.
Urea adds context but is not a filtration marker on its own. It is affected by hydration and by protein intake, so it can move when filtration has not changed. A higher urea with a stable creatinine can reflect low fluid intake or a high protein intake, and a lower urea can reflect a generous fluid intake or a low protein intake.
Uric acid is not a filtration marker. Its blood level can change with cell turnover, alcohol, and some medicines, but it does not measure how well the kidneys filter. It is often included in a kidney panel because it is measured alongside the other lines, not because it describes the same process.
UACR reflects urine albumin loss and is not the same as a blood test. It is a ratio between two urine measurements, so it describes what is escaping into urine rather than what is circulating in blood. Albumin can appear in urine for reasons that vary from day to day, including exercise, fever, and a urinary infection, so a single sample is a weaker signal than a pattern across samples.
None of these patterns is a diagnosis. Each describes a relationship between lines, not a condition.
How to read the report's own grouping
- Read the order. Most reports print creatinine and eGFR first, then urea and uric acid, then the urine ratio. Some laboratories put the calculated values in a separate section or print eGFR on a later page.
- Find the flags. A flag means the laboratory compared the value with its printed range, which may be age- or sex-specific. A flag is not a diagnosis.
- Check which values are calculated. eGFR and UACR are calculated, and some reports print urea as BUN while others print urea itself. The report may say which equation or conversion it used.
- Check the unit. mg/dL and umol/L describe creatinine on different scales, mL/min/1.73 m2 and mL/min are different ways of reporting eGFR, and mg/g and mg/mmol describe UACR on different scales. BUN and urea are different quantities, not two names for the same number.
- Read the remarks. A note about the sample, the collection, haemolysis, or a repeated test can explain a result that looks out of place.
What a flagged result means, and what it does not
A flag means the value sits outside the range the laboratory printed for that line. It does not diagnose a condition. Creatinine and eGFR are read together, and a single flagged value can follow a temporary change such as dehydration or a recent illness. A clinician reads it with the pattern across the panel, the person's history, and other results.
A value inside the printed range is not proof that the kidneys are unaffected, and a flag is not proof that they are. The panel is one part of an assessment. The useful question is what the lines are doing over time and how they sit with the rest of the report.
The cross-year view
Kidney results are more useful as a series than as a single panel. Compare the same line, in the same unit, from the same laboratory where possible. Creatinine can shift with muscle mass, hydration, and recent exercise, and eGFR inherits those shifts. UACR can vary between samples for reasons that have nothing to do with the kidney.
eGFR equations are revised over time. Two reports that use different equations are not automatically comparable even when the units match, and the report may name the equation. Urea printed as BUN and urea printed as urea are different quantities, so check which one the report uses before comparing across years.
Doctano keeps each result with its printed range and places it on the profile's timeline. Names and units are normalized across labs, so the same marker lines up across years, and every point still opens the report it came from. The trend is a prompt for a conversation, not a conclusion.
What this page is not
This page explains the panel in general. It does not interpret your result, diagnose a condition, or recommend treatment. It is not medical advice. Verify the values and units against the original report, and discuss the result with a qualified professional.