Buy a kidney function blood test - measure creatinine, eGFR and urea

Your kidneys are small, hard-working filters that keep going around the clock. They remove waste products, regulate your salts and fluids, and play a role in your blood pressure. Because this often happens unnoticed, a kidney function test can give you a bit more insight into how your body is doing.

This test looks at a number of markers that can say something about the filtering function of your kidneys. Together they offer a picture you can calmly discuss with your GP.

This test can be interesting if you are curious about your kidney function, or if you are dealing with high blood pressure, diabetes in the family, or medication that can put extra load on your kidneys.

It can also fit if you simply want to have your kidneys checked without a specific reason. You decide for yourself when a measurement feels meaningful to you, without any pressure.

This kidney function blood test measures three markers in your blood:

• Creatinine: a waste product from your muscles that your kidneys normally filter out of your blood. Its level can say something about how well that filtering is going.
• eGFR (Estimated Glomerular Filtration Rate): a calculated estimate of how quickly your kidneys filter your blood, based partly on your creatinine, age and sex.
• Urea (BUN): a waste product formed when proteins are broken down and excreted through your kidneys.

Together these values give an impression of the filtering function of your kidneys.

The results can give an impression of how well your kidneys filter your blood. Your eGFR estimates the filtration speed, while creatinine and urea show how much waste is circulating in your blood at that moment.

Your kidney function blood test in context

Good to know: these values are snapshots and can fluctuate due to things like your fluid intake, your diet or intense exercise. On their own they do not provide a diagnosis, but they can be a starting point for a conversation with your GP.

This test requires a small blood draw at a certified lab. In the Netherlands you can choose from more than 750 sample points, so there is almost always a location near you.

After ordering, you pick a location and a moment that suits you. The draw itself usually takes just a few minutes, and you do not need a referral from your GP.

Measuring your kidney function can be valuable at different moments, for example:

• when you want to have your kidneys checked without a direct reason
• when kidney problems, diabetes or high blood pressure run in your family
• when you use medication that can affect your kidneys
• when you want to map out your general health a bit better

A kidney function blood test then gives you a factual starting point to build on.

Your result shows each marker together with a reference range and a short explanation. What counts as usual can vary by laboratory and depends, among other things, on your age, sex and muscle mass.

A value outside the range does not automatically mean something is wrong. Creatinine can be higher after intense exercise or a protein-rich diet, for instance. The doctor helps you place your values in the right context.

For this test you usually do not need to fast. It is a good idea to drink enough around the time of the draw and to avoid heavy exercise or an extremely protein-rich meal shortly beforehand, since those can temporarily influence your values.

Unsure about your own situation or your medication? You can check with your GP in advance, so you feel at ease when you go for your draw.

Your result is usually available online within a few working days. Each value is shown clearly with a reference range and an explanation, so you understand what you see.

Every blood test result includes a professional assessment from a BIG-registered doctor. For treatment decisions, discuss your results with your GP.