Lab tests
Kidney function test explainer
Kidney tests mix measured values with a calculated estimate, and the report rarely says which is which. Add yours below to see creatinine, eGFR, urea and the electrolytes set out row by row with the ranges your laboratory printed.
Explain your kidney function test
- 1. Add itDrop a PDF, take a photo or paste the text.
- 2. Check itPersonal details are removed on your device. You approve what is sent.
- 3. Read itSummary, table of results, terms and questions to ask.
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What you get
- Each result on its own row with your report's units and range.
- A note that eGFR is an estimate, and what it is calculated from.
- Plain definitions of creatinine, urea or BUN, and each electrolyte.
- Questions to ask about results your report flags.
Lines you will usually see on a kidney panel
- CreatinineA waste product from muscle that the kidneys filter out
- eGFRAn estimate of how much blood the kidneys filter each minute
- Urea or BUNA waste product from the breakdown of protein
- Sodium, potassium, chloride and bicarbonateSalts the kidneys help keep in balance
- Urine albumin to creatinine ratio (ACR)How much of the protein albumin is passing into the urine
What this tool cannot tell you
eGFR is calculated from creatinine together with age and sex, so it is less reliable in people with unusually high or low muscle mass and it can move with hydration and recent illness. One result is a snapshot. MedicDecode explains the lines on your report and does not stage or diagnose kidney disease.
Common questions
Why does my eGFR say more than 60 or more than 90 instead of a number?
Many laboratories do not print an exact figure above a certain level because the estimate becomes less precise there.
Is BUN the same as urea?
They measure the same substance but are reported differently, so the numbers and units are not interchangeable. The explanation uses whichever your report gives.
Is eGFR measured directly?
No. It is worked out with a formula from your creatinine result, age and sex. Reports often name the formula used.
Words you may see on this report
Tap a word for its plain-English meaning, an example line and what it does not mean.
- Creatinine
Creatinine is a waste product from normal muscle activity that the kidneys filter out, so its blood level helps show how well the kidneys work.
- eGFR (Estimated Glomerular Filtration Rate)
eGFR is an estimate of how well your kidneys filter waste from your blood, calculated from a creatinine blood test plus details like age.
- Microalbumin
Microalbumin is a test for small amounts of a protein called albumin in urine, an early sign that the kidneys may be leaking protein.
- ALT (Alanine Aminotransferase)
ALT is an enzyme found mainly in the liver; when liver cells are irritated or damaged, more ALT leaks into the blood.
- AST (Aspartate Aminotransferase)
AST is an enzyme found in the liver, muscles, heart and other tissues; raised levels can signal stress or damage in one of these.
- Bilirubin
Bilirubin is a yellow substance made when old red blood cells break down; the liver processes it so it can leave the body.
- CRP (C-Reactive Protein)
CRP is a protein made by the liver that rises quickly when there is inflammation or infection in the body.
- Culture and Sensitivity
A culture and sensitivity test grows germs from a sample to identify them, then checks which antibiotics can stop them.
- Electrolytes
Electrolytes are minerals in the blood, such as sodium, potassium and chloride, that carry an electric charge and help the body work.
- ESR (Erythrocyte Sedimentation Rate)
ESR measures how fast red blood cells sink in a tube of blood over an hour; a faster rate can be a general sign of inflammation.
- Fasting Sample
A fasting sample is blood taken after you have had nothing to eat or drink except water for a set number of hours.
- Ferritin
Ferritin is a protein that stores iron; its blood level gives a good idea of how much iron the body has in reserve.
Medicines connected to this test
Their official labels mention this kind of test. Each is explained in plain English.
- Amlodipine
a calcium channel blocker, a type of medicine that relaxes blood vessels
- Atenolol
a beta-blocker (beta-adrenergic blocker). The label describes it as a beta 1-selective, or cardioselective, blocking agent.
- Bisoprolol Fumarate
a beta-blocker, which the label describes as a synthetic, beta 1-selective (cardioselective) adrenoceptor blocking agent
- Carvedilol
A beta-blocker. The FDA lists it as both an alpha-adrenergic blocker and a beta-adrenergic blocker.
- Empagliflozin
a sodium-glucose cotransporter 2 (SGLT2) inhibitor, a prescription medicine that works on sugar handling in the kidneys
- Enalapril
An angiotensin-converting enzyme (ACE) inhibitor
- Furosemide
A loop diuretic, a type of medicine that helps the body get rid of extra fluid through urine
- Hydrochlorothiazide
A thiazide diuretic, a type of medicine often called a 'water pill'