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eGFR

8 min read
July 21, 2020

What is eGFR?

eGFR or estimated glomerular filtration rate measures kidney function. A GFR measurement is the gold standard in detecting changes in kidney status but it is a complicated procedure. Therefore, an eGFR is often used instead. The measurement is based on blood creatinine levels. Creatinine is a waste product produced from the metabolism of creatine.[1]

Why take a eGFR blood test?

An eGFR blood test measures kidney function. Within the kidneys are small filters called glomeruli which allow waste products to be removed from the blood while at the same time preventing proteins and blood cells from being lost. The rate itself reflects the amount of blood filtered per minute. If an individual’s kidney function is reduced as a result of damage or disease, the filtration rate decreases and there is a build up of waste products in the body.[1]

eGFR is based on blood creatinine levels. The kidneys filter creatinine out of the blood and excrete it in urine at a steady rate. However, if kidney function declines, less creatinine is removed and its level builds up in the blood. Therefore, a creatinine test result can give an estimation of the body’s actual glomerular filtration rate.[1]

An eGFR test is included in Forth’s Vitality & Ultimate blood tests which can be purchased direct from our website. The blood sample can be collected at home using our mobile nurse service and sent to our accredited lab for analysis.

What function does eGFR have in the body?

Because creatinine is a waste product, produced by the body when creatine is metabolised it doesn’t have a useful function within the body. However, it can be used to estimate the body’s glomerular filtration rate and based upon this result, we can interpret how well the kidneys are working.

Creatinine levels vary between individuals and depend on gender, age and muscle mass. Generally, those with an increased muscle mass will have higher circulating creatinine levels which may give a result which is outside of the normal parameters. Plus, creatinine levels will rise and eGFR levels fall transiently after intense exercise but will quickly return to normal.[2]

How do changes in eGFR affect health and wellbeing?

Chronic kidney disease is a major health problem. An eGFR of less than 60ml per minute can indicate early stages of the disease. The symptoms of chronic kidney disease can affect everyday life and may even prevent you from carrying out your daily activities. It can also affect your social life and mental wellbeing, particularly as you may need to pee more often meaning you may have to plan days out in advance. Chronic kidney disease can also affect other body systems and can be a risk factor for other health conditions such as:

kidney failure
cardiovascular disease[3]

If you are worried about your kidney function or just want to check where you fall on the range, you can also test your eGFR levels with a simple at-home blood test.

What can cause eGFR to change?

Chronic kidney disease is a major cause of changes in eGFR.

There are several causes of chronic kidney disease, including:

High blood pressure
High cholesterol levels
Diabetes
Kidney inflammation know as glomerulonephritis
Kidney infections
Kidney stones
Enlarged prostate
Long term use of medications like non-steroidal anti-inflammatory drugs (NSAIDs)
Polycystic kidney disease[4]

Diabetes is the most common cause of chronic kidney disease worldwide.[5]

What are the most common symptoms of kidney disease?

The most common symptoms of chronic kidney disease are:

Weight loss
Reduced appetite
Tiredness
Shortness of breath
Needing to pee more often
Insomnia
Nausea
Headaches
Muscle cramps
Itchy skin
Blood in your urine
Erectile dysfunction in men[3]

How to keep eGFR in the healthy range

Kidney function can be maintained and even improved by making some changes to your lifestyle. Research has shown reducing abdominal circumference in people with metabolic syndrome can improve estimated glomerular filtration rate (eGFR). A greater waist to hip ratio can increase the risk of decreased filtration.

Diet is helpful in improving eGFR, particularly the Mediterranean diet as this reduces the risk of developing chronic kidney disease as well as other medical conditions. [6] The diet has been linked to a lower risk of mortality and is characterised by a high intake of fruit, vegetables, legumes, nuts, cereals, and olive oil as well as a moderate intake of fish. The diet is low in meat, saturated fat and poultry.

Exercise is also fundamental in maintaining kidney health. In fact, studies have shown that individuals with cardiovascular disease and chronic kidney disease can improve their kidney function with exercise therapy. [7]

However, it is important to remember that chronic kidney disease is usually a result of another medical condition such as diabetes or high blood pressure. These types of condition can be prevented by making healthier lifestyle choices. For example, limiting salt intake and eating the correct amount of protein can help to prevent the onset of disease as well as cutting down on consuming bad fats like saturated and trans fats which are found in processed meats as well as cakes, biscuits and pastries. Drinking plenty of water daily is also essential for kidney health. Prolonged dehydration can damage the kidneys and affect their ability to filter the blood. Aim to drink approximately 2 litres of water per day and increase this if you are exercising or exposed to high temperatures.

eGFR Tests

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References

[1] Lab Tests Online. (2014). eGFR-Calc. Creatinine Clearance. Available at: https://labtestsonline.org.uk/tests/egfr-calc-creatinine-clearance

[2] Poortmans, J, R and Ouchinsky, M. (2006). Glomerular Filtration Rate and Albumin Excretion After Maximal Exercise in Aging Sedentary and Active Men. The Journals of Gerontology: 61(11), pp 1181 – 1185

[3] Stevens, L, A et al. (2006). Assessing Kidney Function-Measured and Estimated Glomerular Filtration Rate. The New England Journal or Medicine: 354, pp 2473-83.

[4] NHS. (2016). Overview Chronic Kidney Disease. Available at: https://www.nhs.uk/conditions/kidney-disease/

[5] Jha, V et al. (2013). Chronic Kidney Disease: Global Dimension and Perspectives. The Lancet.

[6] Huang, X., Jiménez-Moleón and Lindholm, B et al., (2013). Mediterranean Diet, Kidney Function, and Mortality in Men with CKD. Clinical Journal of the American Society of Nephrology: 13(5).

[7] Toyama, K., Sugiyama, S and Oka, H et al., (2010). Exercise Therapy Correlates with Improving Renal Function Through Modifying Lipid Metabolism in Patients with Cardiovascular Disease and Chronic Kidney Disease. Journal of Cardiology: 56, pp 142-146.

Medically reviewed

This information has been medically reviewed by Dr Nicola Keay.

Nicola has extensive clinical and research experience in the fields of endocrinology and sport and exercise medicine. Nicky is a member of the Royal College of Physicians, Honorary Fellow in the Department of Sport and Exercise Sciences at Durham University and former Research Fellow at St. Thomas’ Hospital.

Dr Nicola Keay

BA, MA (Cantab), MB, BChir, MRCP.