Kidney Blood Test

eGFR stands for estimated glomerular filtration rate. It is a calculation, based on your creatinine level, age and sex, of how many millilitres of blood your kidneys filter each minute. It is the single most useful number for kidney function and the one the NHS uses to stage kidney disease. A healthy young adult has an eGFR of 90 or more; it falls naturally by about 1 point a year from around age 40.

An eGFR of 90 or above is normal. Results between 60 and 89 are described as mildly reduced and are common in older adults; on their own, without other signs of kidney damage, they are usually nothing to worry about. A result below 60 should be discussed with your GP and repeated, because kidney function is judged on results that are stable over time rather than a single reading. Your GP report sets your figure against your age and explains what it means for you.

eGFR declines gradually with age, so a result in the 60s is common and usually harmless in someone in their 70s, while the same result in a 30-year-old would prompt investigation. The reference range does not change with age, but the interpretation does, which is why your GP report considers your age alongside the figure. Anything at 90 or above is normal at any adult age.

The core blood tests are creatinine, from which eGFR is calculated, and urea. This test provides all three. The other half of a full kidney assessment is a urine test for protein (the albumin to creatinine ratio), which detects early damage before eGFR falls; a GP can add that if your blood results or risk factors suggest it. A blood pressure check completes the picture, since high blood pressure both causes and results from kidney disease.

Yes. A falling eGFR and a rising creatinine and urea are the standard signs of reduced kidney function, and this test picks them up. What a blood test cannot do is detect the very earliest kidney damage, which shows first as protein in the urine while eGFR is still normal. If you have diabetes or high blood pressure, ask your GP for the urine test as well.

Usually there are none, which is why kidney disease is called silent and why testing matters for people at risk. When signs appear they include tiredness, swollen ankles, feet or hands, shortness of breath, blood in the urine, needing to pass urine more often at night, itchy skin and poor appetite. People with diabetes, high blood pressure, heart disease or a family history of kidney disease are advised to have kidney function checked every year even without symptoms.

Yes. The home kit takes a small finger-prick sample that you post back to the laboratory in the packaging provided, and it measures the same three markers as the clinic test with the same GP report. Avoid a large protein meal and heavy exercise the day before, as both raise creatinine temporarily, and drink normally so you are not dehydrated.

Often, yes, when the fall has a reversible cause: dehydration, a recent heavy protein meal or hard exercise, certain painkillers (ibuprofen and other anti-inflammatories), or a temporarily high creatinine from large muscle mass. Long-term kidney function is protected rather than reversed: controlling blood pressure and blood sugar, stopping smoking, keeping weight in range, staying hydrated and avoiding regular anti-inflammatory painkillers all slow decline, and some diabetes medicines now protect the kidneys directly.

A private kidney function blood test costs from £49 at Goodbody Clinic. The home finger-prick kit is £49, a blood draw at one of our clinics is £69 and a nurse home visit is £89. Every option includes laboratory analysis of all three markers and a GP report.

Order the home kit online, book a blood draw at one of Goodbody's 250+ partner clinics across the UK, or arrange a nurse home visit. No GP referral is needed. Find your nearest clinic.