GFR Calculator

Kidneys are one of the most vital organs of our body that remove toxic compounds and waste from the blood as urine. This process is called filtration.

Glomeruli are tiny filters in your kidney that are surrounded by blood vessels carrying blood to and from the kidneys. Glomerular filtration rate GFR, determines how your kidneys are functioning, and are therefore important metric for kidney health.

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About You

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About You

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According to the CDC, more than 1 in 7 American adults have chronic kidney disease (CKD). This is a serious health complication that can end in end-stage renal disease (ESRD) or irreversible renal failure.

Knowing your GFR can help track your kidney’s health. In this post, we explain what a GFR calculator is and how you can use it for the early detection of kidney diseases.

What Is CKD?

Chronic kidney disease is an irreversible decline in renal (kidney) functions (.

Our natural metabolism produces several by-products that are not required by the body and are potentially dangerous. These can lead to high serum creatinine, ammonia, and similar other nitrogenous compounds, but instead all this waste product is removed by the kidneys.

Additionally, kidneys also filter and secrete several chemicals, nutrients, and fluids that are present in surplus amounts. Examples include extra water, salt, chloride ions, acids and bases.

This way, kidneys not only protect your body from potential toxicity but also regulate pH, electrolyte balance, blood volume and pressure.

Several factors can damage the kidneys, thus impacting their filtration.

Causes

The major causes of CKD are as follows:

  • Diabetes induced kidney damage
  • Hypertension (high blood pressure)
  • Renal artery stenosis (narrowing of renal artery obstructing kidney’s vascular supply)
  • Systemic diseases like rheumatoid arthritis, SLE, etc.)
  • Toxins (ex: tobacco)

Other factors that can lead to kidney disease are congenital defects and genetics

Other than these, CKD is also often idiopathic, i.e., with no visible cause.

Impaired Kidney Function and Health Complications

CKD leads to severe complications like:

  • Nausea: One of the first symptoms of CKD is nausea due to the high concentration of ammonia and other nitrogenous compounds are nausea and vomiting.
  • Anemia: this refers to a low red cells (RBC) count in the body. Specialized kidney cells called interstitial cells produce a hormone (chemical) called erythropoietin that is integral for RBC synthesis. Impaired kidney function implies cell damage, which naturally causes low RBCs.
  • CVD: Cardiovascular diseases or CVD like pancarditis (inflammation of all cardiac muscle walls), atherosclerosis (blockage of coronary arteries), excess fluid retention, and high blood pressure occur due to renal dysfunction. CVDs are the most common cause of fatality in patients diagnosed with CKD.
  • Osteodystrophy: CKD leads to hypocalcemia or low calcium count because kidneys are supposed to activate vitamin D, which is then utilized for calcium absorption. Low calcium leads to weak bones and joints.
  • Infection: Kidney damage reduces neutrophil (an immune cell) activity, which increases a patient’s risk of infections.
  • Acidosis: This refers to excess acid in body fluid or low blood pH. A damaged kidney is unable to retain appropriate amounts of bases (bicarbonate ions) in the blood, which results in metabolic acidosis.
  • Sexual and Reproductive Dysfunction: The retention of toxic substances, coupled with the narrowing of blood vessels (stenosis) in CKD, is responsible for several forms of sexual and reproductive disabilities. Some of them include low libido, low sperm count and erectile dysfunction in men, disruption in the menstrual cycle and egg production in women, etc.
  • Encephalopathy: Encephalopathy refers to any disease that alters brain function. The toxins (particularly ammonia) that accumulate in the blood due to kidney damage affect the brain and can cause severe cognitive difficulties.
  • Bleeding: Impairment of platelet activity is one of the manifestations of kidney disease. Platelets cause clotting and, therefore, help prevent blood loss. CKD leads to bleeding, which can progress to hemorrhage and shock.

GFR Calculation

Glomeruli are tiny, sieve-like kidney filters. Understandably, glomerular filtration rate GFR refers to how well your kidney glomeruli are working at removing unwanted substances and waste products from your blood.

Glomerular filtration rate calculation is based on your serum creatinine level.

Creatinine is a non-protein compound produced from the breakdown of a substance called creatine, which is catabolized (broken down) to provide energy to the muscles.

Out of all the waste excreted by the kidneys as urine, creatinine is the best marker to gauge GFR, as it is continuously produced, freely filtered, and not reabsorbed by the kidney.

To know your GFR via the GFR calculator, first, get a blood test done to find out your serum creatinine levels.

Enter the value, along with your age and sex, into the GFR calculator, and processed through a mathematical formula (CKD epi creatinine), you’ll have your GRF results on your screen in no time.

Apart from age and sex, your body size, muscle mass and height measurement, calorie intake, percentage of macros in daily diet, and race also affect GFR.

GFR and Stages Of Chronic Kidney Disease

Once you have your GFR results via CKD epi creatinine, it’s time to check if your kidneys are working fine. Medically, CKD, is divided into five stages:

Stage

GFR Levels

Description

1

>90 ml min

Normal GFR i.e. normal kidneys (no kidney failure)

2

60 – 89 ml min

Early CKD (mildly reduced kidney function)

3A

45 – 59 ml min

Moderate CKD (moderately reduced kidney function)

3B

30 – 44 ml min

Moderate CKD (moderate kidney disease, slightly severe than preceding stage)

4

15 – 29 ml min

Severe CKD approaching dialysis (severe kidney disease, high risk of progression to ESRD)

5

<15 or on dialysis ml min

End-stage renal disease (complete cessation of kidney function)

It should be noted that all forms of CKD are considered medical emergency.

The Next Step

So you tried out a GFR calculator, and your GFR levels point towards kidney disease? Here’s how to go about it.

  • Consult your physician or an experienced nephrologist immediately for medical or professional advice.
  • After taking your detailed medical, personal, and family history, your doctor will get some initial tests done to confirm CKD, look for the cause of high serum creatinine (low creatinine clearance rate), and workout the treatment options. CBC< urinalysis, blood glucose, ECG, renal biopsy and ultrasound are all part of CKD investigations.
  • CKD treatment is specific for each cause. For example, in case of anemia, your nephrologist will suggest iron supplementations, whereas vitamin D tablets will be administered for bone diseases.
  • CKD is irreversible, and to limit renal damage, certain general measures like not smoking, as well as a kidney friendly diet having moderate protein, potassium, phosphate and magnesium intake, low-sodium diet, etc., are important.
  • Severe CKD and ESRD warrant dialysis, which you should discuss with your doctor.
  • It is important to remember that no treatment method can completely cure kidney damage, and therefore kidney transplant is the only permanent solution. Although, listing yourself for a kidney transplant can be difficult and finding a match can be difficult, you should discuss this with your doctor, especially in case of ESRD.