Lab results explained
Kidney, Liver and Inflammation Tests Explained: eGFR, ALT, CRP and ESR
eGFR and ALT come from the chemistry part of a routine blood panel and show how your kidneys and liver are doing. CRP and ESR are separate tests that look for inflammation anywhere in the body. This page explains how they fit together. Each test has its own detailed guide.
Tests in this panel
- eGFR (kidney function)An estimate of how well your kidneys filter blood, calculated from creatinine, age and sex.Read the guide
- ALT liver enzymeA liver enzyme that leaks into the blood when liver cells are irritated or damaged.Read the guide
- C-reactive protein (CRP)A fast-moving marker of inflammation. Rises within hours and falls within days.Read the guide
- ESR (sed rate)A slower marker of inflammation, also affected by age and anemia.Read the guide
Where these tests come from
eGFR and ALT usually appear on a comprehensive metabolic panel (CMP), along with sodium, potassium, glucose, creatinine and other liver tests such as AST, ALP and bilirubin. CRP and ESR are ordered on their own, often when symptoms suggest an infection or an inflammatory condition, or to follow one over time.
Kidneys: eGFR with a urine test
eGFR shows filtering capacity, but kidney damage can show up first as protein in the urine. That is why people with diabetes or high blood pressure are usually checked with both eGFR and a urine albumin test. A low eGFR is confirmed on a repeat test, because dehydration, a large meat meal or intense exercise can lower it for a while.
Liver: ALT in context
A mildly raised ALT is common and often linked to fatty liver, alcohol, some medicines and supplements, or a recent hard workout. Clinicians read it with AST, ALP and bilirubin to see which part of the liver is involved, and usually recheck it before looking further.
Inflammation: CRP and ESR together
CRP and ESR both rise with inflammation but on different time scales. CRP moves within hours and falls quickly with recovery; ESR changes over days to weeks. Neither says where the inflammation is, so they are read with symptoms, an examination and other results, including the CBC.
Why these results connect
Organs affect each other's numbers. Inflammation can raise ferritin; a serious illness or dehydration can lower eGFR for a while; fatty liver often comes with high triglycerides and blood sugar; and long-term kidney disease can cause anemia. Looking at the whole picture over time, rather than one value, gives the most reliable view.
Frequently asked questions
Do I need to fast for these tests?
eGFR, ALT, CRP and ESR do not usually need fasting. If glucose or a lipid panel is drawn at the same time, you may be asked to fast. Avoid a very hard workout the day before, since it can raise ALT and CRP for a while.
What is a normal eGFR?
An eGFR of 90 or above is normal, and 60 to 89 can be normal for older adults when there are no other signs of kidney damage. A result below 60 for three months or more meets the definition of chronic kidney disease.
Is a high ALT serious?
Usually it is mild and has a common cause such as fatty liver, alcohol or a medicine. Very high values, or a raised ALT with yellowing of the skin or eyes, dark urine or belly pain, need prompt medical attention.
Should I get CRP or ESR?
Your clinician chooses. CRP is better for following a fast-changing problem such as an infection; ESR is often used for some long-term inflammatory conditions. Many clinicians order both.
Watch your kidneys, liver and inflammation over time
Add your results to VHT to follow eGFR, ALT, CRP and ESR side by side, and ECHNA, your AI health assistant, explains what changed in plain language.
