Cystatin C blood test in Chiswick

What the test measures

Cystatin C is a protein made at a steady rate by almost every cell in the body. The kidneys filter it out of the blood freely, so when filtration slows, cystatin C rises. Unlike creatinine, its level depends very little on how much muscle you have or how much meat you eat.

NICE guidance recognises cystatin C as a useful confirmatory test in some situations, for example when an eGFR based on creatinine is borderline, or in people with very high or very low muscle mass, such as bodybuilders, older adults or people following a vegetarian diet. Laboratories can use it to calculate an eGFR of its own.

The price includes the blood sample taken at our Chiswick clinic, analysis at the Randox accredited laboratory, a practitioner review of your result with you, and a GP feedback report on request.

Who it is for

• You have a borderline or slightly reduced creatinine-based eGFR and want a clearer picture.
• You are very muscular or take creatine, which can make creatinine look higher than your kidney function warrants.
• You have low muscle mass, for example after illness, with older age or on a plant-based diet.
• You have diabetes, high blood pressure or a family history of kidney disease.
• Your GP has suggested an additional kidney marker.

Understanding your result

Your report shows your cystatin C against the laboratory reference range. A higher level usually suggests the kidneys are filtering less efficiently. Levels can also be influenced by thyroid function, high-dose steroid medicines, smoking and significant inflammation, so these are considered when your result is reviewed.

Your practitioner will look at cystatin C alongside creatinine, blood pressure and any urine findings. A result outside the range is a starting point for a conversation and, where needed, a referral to your GP, not a diagnosis of kidney disease.

Preparing for your test

No fasting or special diet is needed for cystatin C, and recent meals or creatine supplements have little effect on it. Drink water as normal. Please tell us if you take steroid tablets or thyroid medicines, or if you have a thyroid condition, as these can affect the level. Carry on with any prescribed treatment unless your doctor says otherwise.

Cystatin C is part of Kidney Health Extended, which pairs it with creatinine, urea and electrolytes, and of Tired All The Time. You can also browse every blood test and price in Chiswick.

Questions

How much is a cystatin C test in Chiswick?

A cystatin C blood test at Omnia Lifestyle costs £89. The price covers your sample in Chiswick, analysis at an accredited laboratory, a practitioner review and a GP feedback report on request.

Is cystatin C better than creatinine?

Neither is simply better. Cystatin C is less affected by muscle and diet, while creatinine is the standard routine marker. Using both together often gives the most reliable estimate of kidney function.

Do I need to stop creatine before this test?

Creatine has little effect on cystatin C, which is one reason people who take it choose this test. If you are also having creatinine measured, mention your supplement use.

Can thyroid problems change my cystatin C?

Yes. An overactive thyroid can raise cystatin C and an underactive thyroid can lower it, independent of the kidneys. Your practitioner may suggest checking thyroid function if your result is unexpected.