The kidney and UTI: Can urinary tract infections lead to kidney failure?

 Key takeaways:

• It is rare for a simple urinary tract infection (UTI) to directly lead to kidney failure. However, untreated or complicated UTIs can potentially progress to more serious kidney infections.
• For kidney failure to occur, a person might have had acute kidney injury or chronic kidney disease (CKD), a condition where there is a sudden or gradual loss of kidney function. If left untreated, these can progress to kidney failure.
• To reduce the risk of UTI complications. It is important to see a doctor immediately if you suspect a UTI or experience symptoms such as pain during urination, blood in your urine, lower abdominal pain, and fever.
• Proper prevention and treatment of UTIs can go a long way in reducing the risk of kidney complications. This includes staying hydrated, urinating before and after sexual activity, and promptly treating UTIs.  

A urinary tract infection is an infection that occurs when bacteria from the skin or rectum enter the urethra and infect the urinary tract. The urinary tract includes the bladder, ureters, and urethra, and the most common type of UTI is a bladder infection, also known as cystitis. Another type of UTI is called pyelonephritis (kidney infection). Kidney infections are less common but are more serious than bladder infections.

Kidney failure is also called renal failure. It happens when the kidneys are unable to function well in filtering waste products and excess fluid from the blood to the point where kidney replacement or dialysis is required. Various factors, like insufficient blood flow to the kidneys, and diseases like diabetes or high blood pressure, can be major causes of kidney failure.

 Can UTI affect the kidneys and cause kidney failure?

Yes, a complicated UTI can affect the kidneys, but a simple UTI does not directly cause kidney failure.  

According to research, about 1 in every 30 cases of UTI leads to a kidney infection. For kidney failure to occur, a person might have had an acute kidney injury or chronic kidney disease (CKD), a condition where there is a sudden or gradual loss of kidney function. If left untreated, this can progress to kidney failure. 

Kidney failure, which is also known as renal failure, happens when the kidneys are no longer able to perform their vital functions. At this stage, the body requires replacement of the kidney functions in order to maintain kidney health and balance. 

The replacement of kidney function can be achieved through dialysis, which filters waste and excess fluid from the blood using a machine, or through a kidney transplant, where a healthy kidney from a donor is surgically implanted into a patient.

The following could be the reason for kidney failure:

• High blood pressure
• Polycystic kidney disease (An inherited disorder characterized by clusters of cysts in the kidney)
• High blood sugar (diabetes)
• The kidneys not getting enough blood to filter
• Glomerulonephritis (damage to the kidney's tiny filters)

 How urinary tract infection can cause kidney failure

A recent 2022 study indicates that urinary tract infections (UTIs) can accelerate the decline of kidney function. Also, in people with chronic kidney disease, UTIs were found to fasten kidney failure. 

This means that if someone already has chronic kidney disease and develops a UTI, their kidneys may deteriorate more rapidly as compared to those without UTIs. This explains the importance of preventing and effectively treating UTIs to reduce their impact on kidney health.

This study went further to explain an important concern regarding the use of antibiotics, such as fluoroquinolones and co-trimoxazole, in people with kidney failure because these medications reach effective concentrations in the urinary tract. 

These antibiotics were noticed to cause more harm to the kidneys, especially when they are not properly adjusted for kidney function. This can also worsen the decline of kidney function in people who already have UTIs.

 Kidney failure as a risk factor for UTI

Kidney failure can be a risk factor for urinary tract infections (UTIs). In kidney failure, urine may not flow properly or may become stagnant. Some risk factors, like kidney stones, diabetes, and prostate disorders, also predispose people to UTIs and chronic kidney disease because they can also block the urinary tract, thereby causing UTIs and possible kidney failure. 

Additionally, the immune system of people with kidney failure may be weakened. This makes them more vulnerable to infections, including UTIs.

According to a study carried out on 482 patients with chronic kidney disease, it was found that 15.8% had urinary tract infections (UTIs). This means that out of 482 people with chronic kidney disease, 76 of them had UTIs.

Notably, the study showed that patients who were over 75 years old had a higher likelihood of having UTIs, with 41.8% of them having bacterial growth, and those with stage 4 chronic kidney disease had a similar association, with 33.8% of them having UTIs. These findings suggest that older age and advanced stages of kidney failure may also be important risk factors for developing UTIs.

 Other risk factors for UTI

Other risk factors for UTI include:

• Diabetes
• Diarrhea
• Menopause
• Pregnancy
• Dehydration
• Poor personal hygiene
• Incomplete bladder emptying
• Frequent pelvic examinations
• New or multiple sexual partners
• Use of spermicides and diaphragms
• Abnormal urinary tract anatomy or function
• Immune system suppression or inadequacy
• Antibiotic use and increasing bacterial resistance
• Abnormal urination (e.g., incomplete emptying, neurogenic bladder)
• Sexual intercourse (as sex can introduce new bacteria into the urinary tract)

Notably, some of the risk factors for UTI are also risk factors for CKD and kidney failure.

 Symptoms of kidney infection

Kidney infections may cause the following symptoms:

• Chills
• Fever
• Nausea and vomiting
• Frequent or painful urination
• Pain in the back, side, or groin
• Cloudy, dark, bloody, or foul-smelling urine

 How to treat UTI in people with renal failure

Regular monitoring of kidney function, which includes serum creatinine levels and urine output, is essential during the treatment of UTIs in individuals with renal failure. This helps assess the response to treatment and detect any worsening of renal function.

Caution must be exercised when using certain antibiotics. Antibiotics belonging to the classes, aminoglycosides (e.g., gentamycin, amikacin, streptomycin), Nitrofurantoin, and tetracyclines (except doxycycline), should be avoided due to potential kidney toxicity.

Furthermore, some antibiotics do not require dose adjustment, even in severe renal failure. These include azithromycin, ceftriaxone, clindamycin, doxycycline, fosfomycin, linezolid, nafcillin, rifampin, and trimethoprim.

In some cases, intermittent bladder instillations of antibiotics or antiseptic solutions may be helpful. This involves introducing the medications directly into the bladder intermittently. It can be useful for patients with severe or end-stage renal failure, minimal urine output, those who perform intermittent self-catheterization, or when other treatment methods have not been successful.

When kidney function falls below 10% of its normal function, dialysis or a kidney transplant are usually needed. This is especially true for patients with signs of uremia (a buildup of waste in the blood), like nausea, loss of appetite, weight loss, and itching.

Implementing preventive measures like maintaining good hygiene practices, avoiding the use of unnecessary urinary catheters, and addressing any risk factors can help prevent end-stage kidney disease.

 Other complications of UTI

Other complications of UTI include:

• Urinary incontinence (loss of bladder control causing leaking of urine)
• Hypertension
• Renal abscess (collection of pus within the kidney)
• Prostatic abscess (collection of pus within the prostate gland)
• Chronic prostatitis (inflammation of the prostate gland)
• Persistent lower urinary tract symptoms

 When to speak to a doctor

If you suspect or have symptoms of a urinary tract infection (UTI), it is important to speak to a healthcare professional. Some of the common symptoms of a UTI, are frequent and painful urination, cloudy or bloody urine, lower abdominal pain, or fever. Your doctor will carry out appropriate tests and provide treatment to prevent complications and ensure your well-being.