If you came here asking “is my kidney function getting worse”, “creatinine normal but eGFR low”, “how much salt with kidney disease” — you are in the right place. Start with the next box, then keep reading.
None of those? Then nothing below is an emergency, and you can read the rest calmly.
The frail eighty-year-old with the beautiful creatinine.
A result that looks steady may not be.
A steady Creatinine result here is not the reassurance it looks like. It has barely moved — but Lean Body Mass is down 2% over the same stretch, and muscle makes creatinine.
Worth asking: “Would Cystatin C tell us something different? It does not depend on Lean Body Mass.”
A steady CK result here is not the reassurance it looks like. It has barely moved — but Lean Body Mass is down 2% over the same stretch, and CK is a muscle enzyme.
Muscle makes creatinine. The kidney clears it. Lose muscle and you make less of it. Lose kidney and you clear less of it. The number sits still while both are going wrong.
The kidney estimate assumes your muscle is average for your age and sex. When it isn't, the estimate carries that error forward. The fix is a marker your muscles don't make. Cystatin C is the usual one. The same trap turns up wherever a marker's source is fading. Albumin drops when someone stops eating well, not only when the kidney leaks. CK drops as muscle disappears, not only when injury stops. Urea depends on how much protein went in.
Before you read any trend, ask what makes this substance and whether that thing is changing too. If it is, a flat line means nothing and you need a second marker with a different source.
Baxmann AC et al. Influence of muscle mass and physical activity on serum and
urinary creatinine and serum cystatin C. Clin J Am Soc Nephrol. 2008.
Shlipak MG et al. Cystatin C versus creatinine in determining risk based on
kidney function. N Engl J Med. 2013.
Her liver numbers improved when she changed hospitals. Her liver didn't.
Some of your results may not be comparable with each other.
AST came back 200.0 from Tufts on 2024-11-18, and 370.0 from SVMC on 2024-11-22 — 85% apart, days apart.
AST came back 24.0 from SVMC on 2023-06-24, and 21.0 from Tufts on 2023-06-26 — 12% apart, days apart.
AST came back 21.0 from Tufts on 2023-06-26, and 27.0 from SVMC on 2023-06-29 — 29% apart, days apart.
AST came back 25.0 from SVMC on 2023-07-03, and 19.0 from Tufts on 2023-07-05 — 24% apart, days apart.
AST came back 23.0 from Tufts on 2023-09-12, and 28.0 from SVMC on 2023-09-14 — 22% apart, days apart.
AST came back 31.0 from SVMC on 2024-04-18, and 24.0 from Tufts on 2024-04-22 — 23% apart, days apart.
AST came back 25.0 from UIMC on 2024-10-04, and 39.0 from SVMC on 2024-10-07 — 56% apart, days apart.
Albumin came back 3.9 from Tufts on 2024-04-22, and 4.49 from DHMC on 2024-04-22 — 15% apart, days apart.
Albumin came back 3.9 from SVMC on 2024-11-22, and 3.4 from Tufts on 2024-11-25 — 13% apart, days apart.
Albumin came back 3.4 from Tufts on 2024-11-25, and 3.8 from SVMC on 2024-11-27 — 12% apart, days apart.
Albumin came back 3.9 from RRMC on 2026-03-26, and 4.4 from DHMC on 2026-03-27 — 13% apart, days apart.
CK came back 4650.0 from Tufts on 2024-11-18, and 6650.0 from SVMC on 2024-11-22 — 43% apart, days apart.
Creatinine came back 1.66 from Tufts on 2023-06-26, and 2.1 from SVMC on 2023-06-28 — 27% apart, days apart.
Creatinine came back 1.5 from SVMC on 2023-06-24, and 1.66 from Tufts on 2023-06-26 — 11% apart, days apart.
Creatinine came back 1.66 from Tufts on 2023-06-26, and 1.9 from SVMC on 2023-06-29 — 14% apart, days apart.
Creatinine came back 1.22 from UIMC on 2024-10-04, and 1.4 from SVMC on 2024-10-07 — 15% apart, days apart.
Creatinine came back 1.2 from SVMC on 2024-11-22, and 1.32 from Tufts on 2024-11-23 — 10% apart, days apart.
Creatinine came back 1.2 from SVMC on 2024-11-22, and 1.05 from Tufts on 2024-11-25 — 12% apart, days apart.
Creatinine came back 1.05 from Tufts on 2024-11-25, and 1.2 from SVMC on 2024-11-27 — 14% apart, days apart.
Worth asking: “Are these comparable, or should I treat them as separate records?”
Two labs can run the same test on the same blood and get different answers. They use different machines, calibrated differently, with their own idea of normal. Nobody reconciles them, because no single lab ever sees the other one's numbers.
Each lab is internally consistent, so each one looks trustworthy on its own. The error only appears when you line them up, and lining them up is something only the patient is in a position to do. Watch for two shapes. A step in the level exactly where care moved. And two results days apart from different labs that disagree by more than the body could possibly move in that time.
A series is only a series if the same ruler measured all of it. Where the ruler changes, treat the step as an artefact until something proves otherwise.
Standardisation of body composition parameters between GE Lunar iDXA and
Hologic Horizon A and their clinical impact. 2024.
Direct observation: in one longitudinal record, AST averaged 38.7 at one
hospital and 19.8 at another over overlapping years, same patient.
Normal every year for nine years. Then stage four. Nothing was ever abnormal — it was just always a little worse than last time.
Every one of these was normal, and every one of them was moving.
Every one of your Albumin results from DHMC came back inside the normal range (3.50 - 5.10 g/dL) — 30 of them. Over that stretch the number went from 3.87 to 4.6.
Worth knowing: DHMC did not use one range across those results. It used 3.50 - 5.10 g/dL and then 3.2 - 5.2 g/dL. The same number can sit inside one and outside the other.
Which direction is the worrying one for this test has not been settled here, so this is movement, not bad news.
Worth asking: “Could we look at these in date order rather than one at a time?”
A normal range is built from a crowd. It says whether you look like other people. It cannot say whether you are moving, or how fast, or which way. Someone whose usual number is at the low end can lose a third of their function and still land inside the range every single time.
Almost every alert in medicine fires on a threshold. Cross the line, something happens. Stay inside it and nothing does. So a person sliding steadily downhill inside the range triggers nothing, year after year, and each visit ends with good news that was true and useless. The direction and the speed carry the information. The position carries almost none.
Ask of any result: compared with this person's own past, which way and how fast? A number is a dot. Two dots are a difference. Only many dots are a direction.
KDIGO defines chronic kidney disease by abnormality persisting over three
months — the criterion is duration, not a single value.
Roughly nine in ten adults with chronic kidney disease do not know they have it.
When to worry
What you can do yourself
What your results mean
The things that are awkward to ask
Print this, or post it to your portal the night before. It is not a diagnosis and it does not ask anyone to accept anything.
What I noticed
my rings don't fit
What I would like to ask
This may not belong to one person
Swelling can come from the kidney, the heart or the liver, and each one makes the others worse. Whoever sees it first is the right person to start asking.
Could matter to: kidney, heart, liver
Muscle loss makes kidney results look better than they are, and it changes how drugs should be dosed. It matters to more than one of my doctors.
Could matter to: kidney, cancer care, nutrition, physical therapy
This page does not diagnose anything and does not replace your doctor. It reads your own records back to you and suggests questions. Nothing you type here leaves your device.