Your liver and kidneys work all day to clean your blood and keep your body in balance. Problems with these organs often have no symptoms until they are advanced. Two simple blood tests, LFT and KFT, can show how well they are working.
Liver function test (LFT)
The liver processes food, stores energy, makes proteins and removes toxins and medicines from the body. An LFT is a group of tests that check liver health.
What an LFT checks
- SGPT (ALT): an enzyme found mainly in the liver. High levels often mean the liver cells are irritated or damaged. A common upper limit is about 40 to 55 U/L.
- SGOT (AST): an enzyme found in the liver, heart and muscles. A common upper limit is about 40 U/L.
- Alkaline phosphatase (ALP): can rise with liver or bile duct problems, and also with bone growth in children.
- GGT: another liver enzyme, often raised with alcohol use or bile duct problems.
- Bilirubin (total and direct): a yellow pigment from the breakdown of red blood cells. High bilirubin can cause jaundice (piliya). Total bilirubin is commonly up to about 1.2 mg/dL.
- Total protein, albumin and globulin: proteins made by the liver. Low albumin can be seen in long-term liver disease or poor nutrition.
Common reasons for abnormal LFT
- Fatty liver, which is very common in people with belly fat, diabetes or high triglycerides
- Alcohol use
- Viral hepatitis (such as hepatitis A, B, C or E)
- Some medicines and supplements
- Gallstones or bile duct problems
A small rise in SGPT or SGOT is common and is not always serious. Your doctor will look at the pattern of results and may suggest more tests or an ultrasound.
Kidney function test (KFT)
The kidneys filter waste from the blood and remove it in urine. They also control water, salts and blood pressure. A KFT, also called RFT (renal function test), checks how well they are filtering.
What a KFT checks
- Creatinine: a waste product from muscles. High creatinine can mean the kidneys are not filtering well. Common adult range is about 0.7 to 1.3 mg/dL in men and 0.6 to 1.1 mg/dL in women.
- eGFR: an estimate of kidney filtering, calculated from creatinine, age and sex. A value of 90 or above is usually normal. Lower values may suggest reduced kidney function, especially if they stay low over months.
- Blood urea or BUN: another waste product. It can rise with kidney problems, dehydration or a high-protein diet.
- Uric acid: high levels can cause gout (painful joints, often the big toe) and kidney stones. A common range is about 3.5 to 7.2 mg/dL in men and 2.6 to 6.0 mg/dL in women.
- Electrolytes (sodium, potassium, chloride): salts that keep nerves, muscles and the heart working properly.
- Calcium and phosphorus: sometimes included.
Who should check kidney function?
- People with diabetes
- People with high blood pressure
- People with a family history of kidney disease
- People who take painkillers often or for a long time
- Older adults
- People with swelling in the feet or face, or changes in urination
Diabetes and high blood pressure are leading causes of kidney disease, so regular checks are important if you have either.
About reference ranges
The ranges above are common examples. Ranges differ between labs and depend on age, sex and body size. Always use the reference range printed on your report, and discuss any abnormal values with your doctor.
How to prepare
- Fasting is not always needed for LFT or KFT. Some labs advise 8 to 12 hours of fasting, especially when these tests are part of a package.
- Avoid alcohol for at least 24 hours before an LFT.
- Avoid heavy exercise the day before, as it can raise creatinine and some enzymes.
- Drink normal amounts of water.
- Tell your doctor about all medicines and supplements you take.
Frequently asked questions
Is SGPT of 60 dangerous?
An SGPT of 60 U/L is mildly raised. It is often due to fatty liver, alcohol or medicines, and is usually not an emergency. Your doctor may repeat the test or suggest an ultrasound.
Can drinking more water lower creatinine?
Being dehydrated can raise creatinine a little, so drinking enough water helps you get an accurate result. But if your kidneys are not working well, water alone will not fix it. Talk to your doctor.
Is uric acid part of the kidney test?
Many KFT panels include uric acid. You can also book it as a separate test.
Book this test
You can book LFT, KFT or both together with home sample collection. Book a test, see all tests, or compare health packages.
This article is for general information only and is not medical advice. Please talk to your doctor about your symptoms and report.
