Te mārama ki ō hua whakamātaunga oranga whanewhane Understanding your kidney function results
The most common test of how well your kidneys are working is a blood test called a kidney function or renal function test. Your healthcare provider may check your kidney function before or after you start a medicine that can affect your kidneys or as part of a wellbeing check.
Terms used in your kidney function results
Your kidneys balance the salt and water content in your body and get rid of some waste products. They act like a filter for your blood. A kidney function test looks at how your kidneys are handling different salt and waste products.
'Na' means sodium, one of the salts in your blood that your kidneys help to control. Sodium helps your body create energy and keep the right balance of salt and water.
'K' means potassium, another of the salts in your blood that your kidneys control. Potassium is important for your muscles and nerves to work properly.
Urea is a waste product that comes from protein. Your kidneys get rid of it through your wee (urine).
'Creat' means creatinine, a waste product that comes from normal muscle activity. Your kidneys get rid of it through your wee.
'eGFR' means estimated glomerular filtration rate. This is a calculation that shows how much kidney function you have. When you look at your result, it is important to know that kidney function decreases with age, even in people without kidney disease.
Normal kidney function results
If you have a copy of your test results, it will show your results and a normal range for each test.
The normal ranges may vary depending on:
- your gender
- your age group
- whether you are pregnant
- whether you have any underlying health conditions.
So the normal ranges shown on your test results may not be exactly right for you. Discuss your results with your healthcare provider if you are unsure.
High results
If your urea or creatinine levels are high, it can be a sign of kidney damage or not enough fluids (dehydration).
A high sodium level is usually a sign of dehydration.
A high potassium level could be a false reading due to a problem with the blood sample. It could also be a sign of kidney damage.
Low results
Low sodium levels could mean your blood has too much water in it, or it could be due to a medication you are taking.
Low potassium levels mean your body has lost too much potassium through your wee (urine) or from throwing up (vomiting) and runny poos (diarrhoea).
If your eGFR is low, your kidneys are not filtering as well as they should do. This is a sign of kidney damage.
If you have high or low results
If your blood test results for kidney function are too high or too low, talk to your healthcare provider.
Having healthy kidneys is important for your general health and wellbeing. There are several ways you can protect your kidneys.