The 8 Most Common Kidney Diseases

Every day, 12 people in the United States die waiting for a kidney transplant that never comes. Chronic kidney diseases aren't only common in the population, but fatal.

Written and verified by el biólogo Samuel Antonio Sánchez Amador.

Last update: 15 February, 2024

The kidneys are the most important organs of the urinary system. Although each of them only weighs between 5 and 6 grams, their work when filtering blood corresponds to 22% of the pumping output of the heart. These organs are responsible for excreting waste substances and maintaining body homeostasis, but there are certain common kidney diseases that make the process difficult.

Approximately 2 million people worldwide undergo transplants or dialysis to overcome chronic kidney failure each year. Although this figure seems astronomical, it should be noted that it only accounts for 10% of patients with dysfunctional kidneys. Unfortunately, the rest of the patients end up dying for lack of long-term medical care.

Most of us have 2 kidneys, but it’s possible to live with only one of them or even none, as long as the patient is routinely put on intensive dialysis. In any case, survival 5 years after starting this last treatment barely reaches 56%. If you want to know more about the world of kidney disease, keep reading.

What are the most common kidney diseases?

With these few introductory data, we’ve put into perspective that it’s virtually impossible to live long-term without kidneys. The National Kidney Foundation gives us a few more numbers to help us understand the global picture of kidney disease. Some of the most interesting are collected in the following list:

• Chronic kidney disease affects 37 million people in the United States. This represents 15% of the adult population, that is, 1 in 7 older people. The worldwide figure decreases a bit (13.4%), but it’s still astronomical.
• About 90% of people with chronic kidney failure don’t know they have the condition.
• Of the 2 million people undergoing treatment for this disease, almost all of them congregate in 5 countries. These are the United States, Brazil, Germany, Italy, and Japan.
• Less than 20% of affected patients are spread across 100 low-income countries requiring urgent help.

Chronic kidney disease is an immeasurable public health problem, and it only represents one of the most common kidney diseases. With these figures in mind, we’ll dissect the diseases that most often affect the kidneys and how to detect them. Don’t miss it.

1. Kidney failure

As indicated by the National Institute of Diabetes and Digestive and Kidney Diseases, kidney failure is any situation in which the function of the patient’s kidneys falls below 15%. At this point, it’s common to have symptoms derived from the accumulation of toxins and fluids, as these organs aren’t producing urine in the proper way.

Malfunction of a kidney manifests itself with a high amount of creatinine in the blood, a very normal waste product during muscle metabolism. The normal range is 65.4 to 119.3 micromoles/liter of serum, and any number that varies significantly above the upper limit is usually a red flag.

At this point, it should be noted that renal failure is divided into 2 highly interrelated diseases, but with different courses: Acute and chronic. Let’s look at each of these clinical entities separately.

1.1 Acute renal failure

Acute kidney failure occurs when the kidneys suddenly lose the ability to filter waste from the blood. This results in the accumulation of fluids and toxins in the patient’s body, which leads to an imbalance of homeostasis and a change in blood composition.

Among the most common symptoms of acute kidney failure, we can highlight the following:

• Oliguria: A decrease in the amount of urine excreted, with figures less than 400 milliliters per day.
• Body swelling, especially of the extremities: Fluid retention very often causes the legs to swell.
• Shortness of breath, fatigue, and disorientation.
• Nausea and weakness.
• Fast heartbeat and chest pain.
• Seizure and, ultimately, unconsciousness and death.

According to the Nefrología al Día portal, out-of-hospital acute renal failure is due in 70% to prerenal causes and in 14% to obstructive conditions. This means that heart disease, liver failure, taking too much blood pressure medication, and other conditions are more common triggers than damage to the kidney tissue itself.

1.2 Chronic kidney failure

This variant, also known as chronic kidney disease (CKD), worsens over months and years, and patients usually have no symptoms in the early stages. At the pathological level, it’s characterized by glomerular filtration (a process that occurs in microscopic structures) of less than 60 ml/min/1.73 m². As a consequence, these organs lose the ability to concentrate urine.

CKD can be divided into 5 stages, according to Fresenius Kidney Care. These are the following:

• Stage I: Measurable kidney damage occurs, but organ function remains within normal limits. Symptoms in this phase are few, and if they occur, they include high blood pressure, swelling of the legs, urinary infections, and abnormal urinalysis.
• Stage II: There’s a slight loss of kidney function. The symptoms are the same as in the previous case, only more obvious.
• Phase III: Mild-moderate and moderate-severe loss of kidney function. Unusual pain, numbness, tingling, sluggishness, malnutrition, and bone pain also appear at this point.
• Stage IV: Severe loss of kidney function. It involves anemia, decreased appetite, and abnormal levels of nutrients such as phosphorus, calcium, and vitamin D.
• Stage V: End-stage renal failure, characterized by the need for dialysis or transplantation. Serious symptoms appear here, such as shortness of breath, nausea, vomiting, chronic pain in the lower back, generalized body swelling, and more.

Type 2 diabetes and high blood pressure are the most common causes of chronic kidney failure. Blood pressure control and certain medications can delay kidney damage, but when the terminal phase is reached, the prognosis drastically worsens. Once dialysis is started, the patient doesn’t usually live more than 10 years.

2. Kidney stones

While we’ve expanded on kidney failure because of its medical importance, we’ll provide a more general overview of each condition from now on. Kidney stones occur when the amount of substances that crystallize (such as calcium and uric acid) is greater than that which can be diluted in the urine, thus causing their precipitation.

There are different types of kidney stones, mostly depending on the chemical composition of the crystal stool. It should be noted that calcium stones are the most common, accounting for 75-85% of all types. The age of onset of the formation of these kidney stones reaches its epidemiological peak between 20 and 39 years of age.

It’s estimated that between 1% and 15% of the world’s inhabitants have kidney stones at some point in their life. The typical symptoms are as follows: Throbbing pain in the sides, discomfort in waves and fluctuating intensity, urine of atypical colors, a constant need to urinate, nausea, vomiting, fever, and chills (in case of infection).

3. Urinary tract infections

Urinary tract infections (UTIs) are a frequent problem in primary care, as indicated by the Microbiology Service of the Hospital de Móstoles. These conditions are much more common in women, as it’s estimated that up to 60% of the female gender will have at least one UTI during their entire life.

UTIs can affect different parts of this device, each with different symptoms. We’ll give you some examples in the upcoming sections.

3.1 Cystitis

The term “cystitis” refers to inflammation and infection of the bladder. It’s characterized by a very characteristic symptom picture: Pain and stinging when urinating, very low or very high frequency of urination, permanent feeling of wanting to urinate, and, sometimes, blood in the urine. It’s always fever-free unless the infection has spread to other places.

The bacterium that usually triggers cystitis is Escherichia coli, reported in 85% of uncomplicated infections in sexually active women. Vesicoureteral reflux, diabetes, the presence of stones, pregnancy, and menopause are risk factors that can contribute to the onset of infection.

3.2 Pyelonephritis

Pyelonephritis is an infection that affects the pelvis, parenchyma, and calyces of the kidneys. It originates in the urinary tract and goes up until it reaches the kidney tissue. Two variants can be distinguished within this UTI:

1. Acute: The infection is evident, but there’s no destruction of the kidney tissue.
2. Chronic: Damage occurs to kidney tissue, which reduces its ability to function.

If left untreated, pyelonephritis can lead to bacteremia (the entry of pathogens into the blood), septicemia, and multiple organ failure. Antibiotics are always the first line of treatment to stop the infection, but pain relievers and fever reducers are also often prescribed to control pain and fever.

3.3 Urethritis

As you can imagine, this UTI occurs when the infection takes place in the urethra. As indicated by the United States National Library of Medicine, the bacteria that generally cause this condition are E. coli, Chlamydia trachomatis, and Neisseria gonorrhoeae. The herpes simplex virus and cytomegalovirus can also cause it.

Just as certain urinary tract infections are typical of the female gender, urethritis is more common in males. Some of the symptoms are as follows: Blood in the urine and semen, painful urination, fever, purulent discharge from the penis, swollen groin lymph nodes, tenderness, and itching.

4. Nephrotic syndrome

According to the American Kidney Fund, nephrotic syndrome isn’t one of the most common kidney diseases per se, but rather a set of symptoms that indicates that something’s wrong with the kidneys. This clinical picture includes significant levels of protein in the urine, low protein levels and high cholesterol in the blood, and an increased risk of developing blood clots and swelling.

One of the most illuminating signs of nephrotic syndrome is albuminuria, or in words, the presence of the protein albumin in the urine. This compound performs many vital functions in the blood, so it shouldn’t be excreted in excess with urination. Normal albumin levels in pee are 30 milligrams/24 hours, and anything above this is a sign of suspicion.

People of all ages (especially children), ethnicities, and conditions can experience symptoms of nephrotic syndrome throughout their lives. Diseases that affect kidney tissue are the main triggers of this condition, but the consumption of certain drugs (such as non-steroidal anti-inflammatory drugs or antibiotics), HIV, hepatitis, and malaria can also cause it.

5. Polycystic kidney disease (PKD)

Although polycystic kidney disease isn’t the most common kidney disease in the world, it deserves exceptional attention given its intricate etiology. We’re facing a condition of hereditary nature, which means that it’s inherited from parents to children. In this chronic disorder, cysts form in the kidneys over time, preventing them from functioning.

PKD is the most common genetic threat, affecting up to 12.5 million people in the world. Two pathological variants can be distinguished according to the inheritance pattern of the disease. These are the following:

1. Autosomal dominant PKD: The disease-causing gene mutation (PKD1, PKD2, or PKD3) is located on a non-sex chromosome and is dominant. This means that, with one of the 2 parents presenting it, the child has a 50% chance of inheriting the condition. It’s the most common and chronic form.
2. Autosomal recessive PKD: The causative mutation is on a non-sex chromosome. In any case, this picture is much rarer, as a carrier or sick parent will never have an affected child unless their partner is also sick or is a silent carrier. If both parents are carriers, the probability that one child will be affected is 25%.

Dominant PKD is much more common in the general population and is responsible for up to 15% of kidney transplants. It causes symptoms very similar to those of other conditions already mentioned (blood in the urine, back pain, kidney stones, abdominal fullness, etc.) but, unfortunately, today there’s no cure for it.

Common kidney diseases and their medical significance

Learning about common kidney diseases is a must, as its importance isn’t only medical. For example, in the United States, 12 people die every day waiting for a kidney transplant, while 100,000 patients are waiting for their lives to be saved. Every year, 3,000 more people are added to the need for treatment.

Only in the United States does the lack of donors represent a medical crisis, so imagine the situation in low-income countries with weak health infrastructure.

In some cases, accessing treatments or transplants becomes complex. Our recommendation will always be health care through prevention.