Difference Between Kidney Infection and UTI

Illustration of the difference between kidney infection and UTI


Kidney infection and urinary tract infection (UTI) can be mistaken for each other because both affect the urinary system and have similarities in terms of cause, symptom, diagnosis, and treatment. Each, however, has its unique attributes that patients should know to ensure that they get the correct medical treatment.

The urinary tract

To understand the difference between urinary tract infection (UTI) and kidney infection, it can be helpful to first understand the anatomy of the urinary tract or the urinary system.

The primary function of the urinary system is to hold, transport, and extract wastes from the body in the form of urine. The urinary tract holds the bladders, kidneys, ureters, and urethra, each of which has its unique functionalities.

Kidneys are responsible for filtering wastes from the blood and extract it in the form of urine. The ureters will then transport the urine to the bladder, which stores the urine. When the bladder reaches its maximum capacity, it will then excrete the urine out of the body via a thin tube or the urethra.

When infection-causing bacteria reach the urethra, they can infiltrate the urinary tract and damage the organs, and thereby disrupt the normal mechanism of the urinary tract.

Kidney infection and UTI: similarities and differences

Kidney infection and urinary tract infection are related but are totally different from each other. UTI refers to the infection in any of the organs in the urinary system, but usually in the lower part where the bladder and the urethra are located. UTI can be a urethra inflammation (urethritis), bladder infection (cystitis), and kidney inflammation (nephritis). UTI is the most prevalent type of infection among young children, women, and elderlies, accounting for more than 10 million hospital visits in the US each year.

Kidney infection (pyelonephritis), on the other hand, is a type or a complication of UTI affecting mainly one or both kidneys. Kidney infection can be uncomplicated, complicated, or recurring/chronic.


The common causes of UTI and kidney infection are much the same. Both infections develop when bacteria like Escherichia coli (E. coli) infiltrate and infect the urinary tract. Experts say that bacterium E. coli account for almost 90% of infections in the urinary system. Normally, persons who have poor hygiene or engage in unprotected sexual intercourse are prone to E. coli and other bacteria. In women, for one, improper wiping of their genitals can introduce infection-causing bacteria to their urinary tract.

Other causes of UTI and kidney infection include preexisting illnesses that weaken the immune system, hormonal changes, and insertion of foreign materials like catheters.

Is UTI the only disease that can give rise to kidney infection?

No. Kidney infections do not only contract from the urinary tract or bladder infection. It can also develop in men with kidney stones and an enlarged prostate in men. These medical conditions can affect urine storage and transport, usually preventing the urine to flow normally from the kidneys to the urethra. As a result, bacteria germinate in the blocked urine and eventually infect the kidneys.

Signs and symptoms

In terms of signs and symptoms, UTI and kidney infection are in some way alike. During the early manifestation of a kidney infection, patients may experience symptoms similar to that of UTI such as changes in urine smell and color, frequent but scanty urination, painful urination, general malaise, pain in the lower abdomen, chills, and fever. But if patients have mistaken the symptoms of kidney infection for that of UTI, they may not receive immediate and proper medication. Thus, patients should also watch out for distinct signs and symptoms.

Patients with UTI may have a fever but not as high as that who have kidney infections. Normally, fever caused by UTI is mild and stays below 101 degrees Fahrenheit, while fever due to kidney infection can exceed that threshold.

Patients with kidney infection may experience more intense symptoms like increased pains in the lower abdomen, sides, and back; nausea; vomiting; diarrhea; lost appetite; extreme shivering; and confusion in elderly patients.

Treatment and Diagnosis

Diagnosis of both UTI and kidney infection may involve urinalysis, urine culture, ultrasounds. In kidney infection diagnosis, however, the patient may be required to undergo physical exam such as pelvic exam in young women. It may also involve thorough physical assessment and medical history review to see the recent or current illnesses that may be a factor in the development of the infection.

After diagnosis, both UTI and kidney infection can then be cured using antibiotics. However, some experts say that UTI – if not recurring – can be treated with home remedies alone or without the aid of antibiotics. But in a kidney infection, it is not recommended to cure the infection with home remedies alone because improper treatment can worsen the condition, which can give rise to more severe complications such as permanent kidney damage. Although not all kidney infection cases require hospitalization, patients should faithfully follow their treatment regime.

Prevention: From UTI to Kidney Infection

Untreated UTI can result in kidney infection. This happens because the bacteria in the lower urinary tract eventually reach the upper part of the urinary system where the kidneys are contained. This is why preventing UTI is a must.

UTI can be prevented through proper hygiene, safe sexual intercourse, and pee-on-demand habit. But anatomy (female are more at risk for developing UTI), preexisting medical condition (e.g., kidney stone and enlarged prostate), and poor diagnosis (e.g. no urine culture) should also be considered because these can contribute to the development of kidney infection.