What Does 3b Mean in Kidney Disease?

Medically Reviewed on 11/15/2022
What Does 3b Mean in Kidney Disease
In stage 3b kidney disease, eGFR is between 30-44 mL/min. Symptoms may include back pain, abnormal urination, hypertension, and anemia.

Kidney health is estimated through glomerular filtration rate (GFR), which is the rate at which fluid is filtered through the kidneys. Lower GFR numbers indicate decreased kidney function.

Stage 3 kidney disease is separated into two stages:

  • Stage 3a: eGFR between 45-59 mL/min
  • Stage 3b: eGFR between 30-44 mL/min

At this stage, kidney disease may not cause symptoms but can cause health complications as waste builds up in your body.

What is kidney disease?

Healthy kidneys filter the blood through tiny structures called nephrons, which remove waste, control fluid balance, and maintain electrolyte balance. When your kidneys are damaged, they cannot function properly and waste can build up in the body. 

There are two types of kidney disease:

  • Acute kidney disease: Kidneys suddenly stop functioning suddenly
  • Chronic kidney disease: Kidney function gradually declines for over 3 months

What causes kidney disease?

Kidney damage can be caused by the following conditions:

  • Type I or II diabetes
  • High blood pressure
  • Glomerulonephritis (inflammation of the kidney's filtering units)
  • Interstitial nephritis (inflammation of the kidney's tubules and surrounding structures)
  • Polycystic kidney disease or other inherited kidney diseases 
  • Prolonged obstruction of the urinary tract due to conditions such as enlarged prostate, kidney stones, and some types of cancer
  • Vesicoureteral reflux (a condition that causes urine to back up into your kidneys) 
  • Recurrent kidney infections

How are the stages of kidney disease determined?

When somebody is diagnosed with kidney disease, the primary step is to determine the stage of the disease. The National Kidney Foundation uses five stages to help doctors determine a plan of treatment based on how much kidney function is remaining. 

In addition to using eGFR numbers to assess kidney health, a serum test to measure creatinine levels in the blood also helps with staging kidney disease. Creatinine is a byproduct of creatine phosphate (a crystalline compound that your body produces from regular muscle movement) after metabolization. The higher the amount of creatinine, the less it is being filtered by your kidneys.


The only purpose of the kidneys is to filter blood. See Answer

What are the five stages of kidney disease?

Stages of kidney disease are based on how well the kidneys perform their function -- filtering waste and additional fluid from the blood. The five stages range from very mild (stage 1) to kidney failure (stage 5):

  • Stage 1: In stage 1, eGFR is 90 mL/min or higher, indicating that the kidneys are working at 90% or better. While kidney damage is identified, they function normally at this stage. However, there may be other signs that the kidneys are not healthy, such as the presence of proteins in urine. Your doctor may suggest restricting protein in your diet, controlling glucose levels, quitting smoking, and practicing overall healthy habits.
  • Stage 2: In stage 2, eGFR is somewhere in the range of 60-89 mL/min. GFR is slightly decreased, and there may be some signs of insufficient kidney function. There are no symptoms at this stage, but tests may detect kidney damage. Your doctor may continue to recommend restricting protein in your diet, controlling glucose levels, quitting smoking, and practicing overall healthy habits.
  • Stage 3: In stage 3, eGFR is somewhere in the range of 30-59 mL/min. At this stage, kidney disease can be determined with a blood test. If symptoms do appear, it is usually during stage 3b and may include back pain, swollen hands and feet, abnormal urination, hypertension, anemia, and bone disease. You should visit a nephrologist who may recommend proper nutrition, changes in exercise, and prescription medications and supplements.
  • Stage 4: In stage 4, eGFR is somewhere in the range of 15-29 mL/min. At this point, it may be necessary to visit the nephrologist at regular intervals for testing. You and your primary care physician (PCP) will start discussing treatment options in the case of kidney failure, which include dialysis, kidney transplant, or palliative care. If you choose dialysis, your PCP will explain the different types of dialysis treatments available, such as hemodialysis (done in a medical environment and includes the use of a machine) and peritoneal dialysis (done at home and includes the insertion of a cleansing agent through a catheter into the lining of the abdomen).
  • Stage 5: In stage 5, eGFR is under 15 mL/min, and your body is either going into kidney failure or is in kidney failure. This phase of the disease is also called end-stage kidney disease or end-stage renal disease (ESRD). Without properly functioning kidneys, waste products that have collected in your circulation system reach toxic levels.

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Medically Reviewed on 11/15/2022
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