The National Kidney Foundation notes that more than 37 million American adults are living with kidney disease, and the majority don’t even know it [1]. One of the most effective ways to keep an eye on your kidneys performance is by understanding your kidney health and function.

Normal kidney function typically involves:

  • Filtering waste products
  • Balancing bodily water-salt ratio
  • Regulating blood pressure
  • Regulating red blood cell production
  • Regulating acid levels

See also: Can Medication Damage Your Kidneys?

Check out our Kidney Health Knowledge Hub for the insights you need to stay on top of your kidney health.

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What is normal kidney function?

Since many of those living with kidney disease don’t experience signs or symptoms until the disease has progressed, understanding normal kidney function is vital to understanding your kidney health.

From the filtering of waste products to the water balance in the body - the kidneys perform many crucial functions. Some of the kidneys key functions include:

Filtering Waste Products

The kidneys filter out toxins, excess salt, urea, and waste products by flushing them out of the body with urine. If the body’s waste products build-up, it can lead to kidney disease[2].

Balancing Bodily Water-Salt Ratio

Your kidneys are one of the body’s primary ways of maintaining a stable salt-water balance. It does this by releasing excess sodium in urine and by actively retaining or releasing water out of the body.

Regulating Your Blood Pressure

If blood pressure is low, the kidneys produce a protein called angiotensin and a hormone called renin - both work together to constrict the vessels and bring your blood pressure to a more stabilised level[3].

Regulating Red Blood Cell Production

The kidneys regulate red blood cells by producing a hormone called erythropoietin (EPO). The kidneys increase the production of EPO as soon as there’s a shortage of red blood cells in the tissues in order to regulate red blood cell production[4].

Regulating Acid Levels

In response to increased acidity in the body, the kidneys attempt to secrete more hydrogen and generate more bicarbonate to regulate the body's acidity levels and ensure PH levels are balanced.

What percentage of kidney function is normal?

When it comes to finding out more about your kidneys performance - a blood or urine test is usually the go to. The test commonly tests for eGFR (estimated glomerular filtration rate); this is a simple calculation to determine how well your kidneys are filtering blood.

The below numbers from the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), show what’s considered ‘normal’ and what might be looking further into:

  • eGFR of 60 or higher is in the normal range
  • eGFR below 60 may mean kidney disease
  • eGFR of 15 or lower may mean kidney failure

See also: Can too Much Protein Damage Your Kidneys?

What should my GFR be for my age?

If the glomerular filtration rate (GFR) is low, it may indicate that the kidneys are not working as they should.

According to the National Kidney Foundation, a normal glomerular filtration rate in adults is above 90, though this 'normal' rate may differ based on age.

  • 20-29 years: 116
  • 30-39 years: 107
  • 40-49 years: 99
  • 50-59 years: 93
  • 60-69 years: 85
  • 70+ years: 75

It's important to note that a low GFR may indicate kidney disease but early detection and treatment may help the kidney disease worsening.

What is kidney disease?

In simple terms, kidney disease means your kidneys have become damaged and can no longer perform their key functions properly. It’s a serious condition and it’s important to receive immediate medical care.

There are two forms of kidney disease:

  • Acute kidney disease is known to occur pretty suddenly and over a short period of time, it’s sometimes referred to as acute kidney injury.

  • Chronic kidney disease is a long-term condition which can get worse over time, sometimes developing into chronic kidney failure,

What are the signs of kidney disease?

Acute kidney disease develops rapidly and tends to be more common in those who are already critically ill and hospitalized. Sometimes acute kidney failure may not cause any symptoms.

If symptoms do occur, some common indicators include:

  • Chronic fatigue
  • Urinating infrequently
  • Fluid retention
  • Shortness of breath
  • Chest pain or pressure

Chronic kidney disease refers to the gradual loss of kidney function, in the early stages it’s common for very few signs or symptoms to appear.

If symptoms do occur, some common indicators include:

  • Loss of appetite
  • Fatigue and weakness
  • Changes in urinating
  • Muscle twitches and cramps
  • Persistent itching

What causes Kidney Disease?

Causes of Acute Kidney Disease

If you have a condition which slows blood flow to your kidneys or have experienced direct damage to your kidneys, you’re more likely to experience acute kidney disease.

Some conditions which might cause acute kidney disease include:

  • Blood pressure medications
  • Heart attack
  • Heart disease
  • Infection
  • Liver failure

Causes of Chronic Kidney Disease

Chronic kidney disease mainly occurs as a result of a disease or condition which impairs kidney function which damages the kidneys function over a period of time.

Some conditions that can cause chronic kidney disease include:

  • Type 1 or type 2 diabetes
  • High blood pressure
  • Glomerulonephritis
  • Polycystic kidney disease
  • Recurrent kidney infection

Should you check your kidney function?

If you’re concerned about symptoms that you’re experiencing, it’s important to make a trip to your doctor for a check-up.

If you simply want to know a bit more about your kidney health, with LetsGetChecked’s Kidney Function Test, you can monitor your kidney function and performance and receive your online results within 5 days.

You should consider taking a Kidney Function Test if any of the below are applicable to you:

  • You suffer from high blood pressure
  • You suffer from diabetes
  • You have suffered an acute injury
  • You have persistent urinary tract infections
  • You have kidney disease or a family history of one
  • You have kidney stones or a family history of them
  • You have a high protein diet
  • You have been taking performance-enhancing drugs

Check out our Kidney Health Knowledge Hub for the insights you need to stay on top of your kidney health.

Add descriptive tag

Buy a Kidney Function Test

Check in on your kidney health with our testing option.


  1. National Kidney Foundation. 10 signs you may have kidney disease. Online:
  2. Beaumont Hospital Kidney Centre. The Urinary System. Online:
  3. You and Your Hormones. Angiotensin. Online:, 2019
  4. You and Your Hormones. Kidneys. Online:, 2019
  5. You and Your Hormones. Kidneys. Online:, 2019