What brought you here
Your lab results flagged your kidneys
Most people meet their kidneys through a lab report. A number is highlighted, a note says to follow up with a specialist, and nobody has explained what the number is. Here's what it is.
What creatinine and eGFR actually measure
Creatinine is a waste product your muscles make every day. Healthy kidneys clear it steadily, so the level in your blood stays fairly flat. When filtering slows, creatinine builds up — so a rising creatinine is an indirect way of watching your kidneys work.
eGFR takes that creatinine level and estimates how much blood your kidneys filter per minute. The 'e' matters: it's an estimate, calculated from your creatinine, age, and sex. Muscle mass affects it. Being very muscular, or having lost a lot of muscle, can push the estimate off in either direction.
One result is not a diagnosis
A single low eGFR doesn't establish chronic kidney disease. The definition requires the change to persist for at least three months, which is why the next step after an abnormal result is usually to repeat it rather than to start treatment.
eGFR also moves for reasons that have nothing to do with lasting damage. Dehydration, a recent illness, a course of anti-inflammatory painkillers, and some antibiotics can all push it down temporarily. Part of the first visit is separating a real trend from a bad day.
What the stages mean
Kidney function is described in five stages, and the number of the stage is not a countdown. Most people with stage 3 stay at stage 3 for many years, and quite a few never progress further. What determines that is largely what happens next — blood pressure, blood sugar, which medications you take and which you avoid.
The useful question is not which stage you are at. It's which direction you're moving, and how fast.
Sooner rather than later
Call your doctor or come in promptly if, alongside the lab result, you have:
- A sharp drop in how much you're urinating.
- Swelling that came on quickly, or shortness of breath.
- Nausea, confusion, or unusual drowsiness.
- A creatinine that jumped substantially in a matter of days rather than drifting over years.
What happens next
What we do with the number
- We repeat and confirm, and look back at older results to see the trend rather than the snapshot.
- We check your urine for protein, which tells us more about risk than eGFR alone does.
- We review every medication and supplement you take, since some are hard on kidneys and doses of others need adjusting.
- We look for the cause — most often blood pressure or diabetes, sometimes something else entirely.
- We set a plan aimed at holding function steady, and we tell you what your own numbers should look like.
Questions people ask us about this
My eGFR is 55. Is that bad?
It's below the usual threshold of 60, which is why it was flagged — but on its own it's a reason to look further, not a diagnosis. It matters a great deal whether it has been 55 for six years or was 80 last spring, and whether there's protein in your urine. Bring your older lab results if you have them; the trend tells us more than the number.
Why do I feel completely normal?
Because kidneys are built with a lot of reserve. People generally feel well into the moderate stages, which is exactly why this gets found on a blood test rather than because someone felt unwell. Feeling fine is not evidence that the result was wrong.
Can kidney function come back up?
If the drop was caused by something temporary — dehydration, an illness, a medication — it often recovers once that's addressed. Long-standing damage generally doesn't reverse, but the rate of decline can very often be slowed, and that's what most of the treatment is aimed at.
Not sure whether you need a kidney specialist?
Call and ask. Our staff will tell you whether this is something we should see, what your plan requires, and what to bring. A real person answers, and the whole staff speaks Spanish.