UTI vs. Kidney Infection: Understanding the Key Differences

If you’ve ever had a urinary tract infection (UTI), you know how uncomfortable it can be. UTIs can affect the kidneys, bladder, and the connecting tubes, and millions worldwide have dealt with the common symptoms like pain, frequent trips to the bathroom, and that relentless urge to go.

Without treatment, what starts as a simple UTI can sometimes lead to more serious issues, as bacteria can move up the bladder and even reach the kidneys.

In this blog, we’ll walk through what you need to know about UTIs and how to recognize the early signs of a kidney infection.

What is a UTI? 

The entire urinary tract consists of kidneys, ureters, bladder and urethra. Together, they work to remove waste from the body in the form of urine. The kidneys filter the blood to rid waste products from the bloodstream, making and concentrating the urine. The ureters are the tubes that deliver the urine from the kidneys to the bladder. The bladder stores the urine until it is ready to be removed from the body through a tube called the urethra. 

Under normal conditions, this urinary tract is sterile, meaning there should be no bacteria. When well-hydrated, your body naturally flushes the bladder and connected tubes regularly, preventing microbes from harbouring and invading.

When a microbe like bacteria or — less frequently, fungi — infect anywhere along this tract, it’s called a UTI.

The main types of UTIs differ according to where the infection takes place and most commonly include: 

• Acute Cystitis: An infection of the bladder and lower urinary tract 
• Pyelonephritis: An infection of the kidneys and upper urinary tract

What is a kidney infection? 

A kidney infection (pyelonephritis) is a type of UTI that occurs when an untreated lower urinary tract infection spreads up to the kidneys through the ureters.

When an infection extends beyond the bladder and reaches the kidneys, it is considered to be a complicated UTI as it brings more health risks, including:

• Risk of bacteria entering the bloodstream (bacteremia)
• Permanently damaging your kidneys
• Becoming septic

Sepsis is one of Canada’s leading causes of death, taking the lives of over 2,000 Canadians each year.

Causes of UTIs and kidney infections

A study from the Canadian Journal of Urology reports that up to 95% of the time, uncomplicated UTIs are caused by E. coli bacteria. The bacteria transfer from the anus to the urethra to enter and infect the urinary tract. Spreading from the urethra to the bladder, the bacteria can cause a bladder infection (bacterial cystitis). 

If left untreated, the infection can further spread up the ureters to one or both of the kidneys, known as pyelonephritis. From the kidneys, the bacteria can enter the bloodstream causing bacteremia and systemic infection and eventually sepsis. 

Other less common causes of UTIs include: 

• Infections spreading to the kidneys from another part of the body through the bloodstream or lymphatic system
• A blockage in the urinary tract such as from a kidney stone, enlarged prostate, or prolapsed uterus 
• Following surgery on your urinary tract

Certain health conditions can increase your risk of developing a UTI. Conditions that increase this risk may include: 

• Diabetes 
• Recent or recurrent UTIs
• Postmenopause
• Having a shorter distance between the anus and urethra 
• Pregnancy 

Symptoms of UTIs vs kidney infections 

UTIs without kidney or systemic symptoms, like fever or chills, are classified as acute uncomplicated UTIs, or cystitis. Keep in mind that sometimes there can be no symptoms in cystitis at all. This is referred to as asymptomatic bacteriuria.

However, when there are symptoms, the classic and most common symptoms of cystitis include: 

• Burning or painful urination (dysuria)
• Urinating more often (increased urinary frequency)
• Urinary urgency

Lower abdominal pain, foul smelling urine or urine that is more cloudy can also occur with bladder infections. Symptoms like fever or chills suggest a more widespread infection is brewing that is potentially involving the kidneys. 

A kidney infection often presents with more systemic symptoms and can include:

• Fever (A temperature over 38 degrees Celsius or 100 Fahrenheit)
• Chills 
• Back or flank pain
• Nausea or vomiting
• Fatigue or having low energy 
• Tenderness along the bottom of the ribs on your back (costovertebral angle) 
• Pelvic or perineal pain
• Blood or pus in the urine  

Symptoms may be different from one person to the next, and can be more difficult to identify in the elderly, when confusion may be the only sign. Identifying the type and severity of UTIs is important for treatment decisions. 

Treatment options for UTIs and kidney infections

Determining the exact cause of the infection can help aid treatment decisions to prevent further spread or recurrence of infection. There’s a few ways a doctor may try to test you for infection:

• A midstream urine sample (meaning releasing a little urine before starting the collection process) is sent to the lab to analyze the urine and identify the exact bacteria causing the infection 
• Blood testing is reserved for very sick patients, often requiring hospital admission
• Imaging studies like an ultrasound, CT scans or an MRI are not needed for most UTIs but can be helpful when there are concerns of recurrent infections, obstruction, or structural abnormalities
• In other instances, an examination may be needed to help rule out other conditions that may present similarly like pelvic inflammatory disease or prostatitis for example

Treatment for UTIs include a course of antibiotics. Well-tolerated, broad spectrum antibiotics are usually selected first to cover a range of bacteria that commonly cause UTIs. When the urine culture results become available, you may be switched to a more specific antibiotic.

The exact antibiotic depends on a few factors:

• What bacteria is causing the infection 
• The severity of the infection
• Allergies to medications
• Recent antibiotic use or UTI 

The duration of treatment varies between antibiotics and can be as short as one single dose, or range from three to seven days for bladder infections. More serious infections involving the kidneys often require a longer course of treatment, typically seven to 10 days, or in severe cases require hospital admission and intravenous antibiotics. 

Acetaminophen or ibuprofen is sometimes used to alleviate the discomforts of UTIs. 

Prevention strategies 

Your body has natural defense mechanisms in place to prevent UTIs from starting such as regular flushing and emptying of the bladder and connected tubes. There are a few things you can do to prevent them from occurring:

1. 1. Hydrate. Staying hydrated will allow your body to flush and empty the bladder every few hours with more diluted urine. This prevents stasis of urine and makes it more difficult for bacteria to cause infection if they do find a way to enter the urinary tract. The exact amount of daily fluids needed isn’t the same for everyone, especially anyone with pre-existing health conditions like chronic kidney disease who may have a restricted daily amount of fluid they can safely consume. Connect with a healthcare provider before making any drastic changes to your fluid intake. 
   2. Avoid holding urine. It’s important to empty your bladder fully when you pee and not to delay emptying when feeling your bladder is full whenever possible. Delaying a washroom break concentrates the urine and provides more time for bacteria to invade and spread before getting flushed out again. 
   3. Practice good hygiene. Wiping from front to back can prevent introducing bacteria from the gastrointestinal tract around the anus to the urethra. For someone prone to UTIs, emptying their bladder after having sex can help remove bacteria that may have entered the urethra. They should also avoid bubble baths, bath oils, perfumed soaps, and vaginal douching. 
   4. Adjust your diet. Reduce or avoid consuming alcohol and caffeine. Both can give you the feeling of needing to empty your bladder more often. 
   5. Cranberry. Consuming cranberry in juice or capsule form can help reduce the risk of symptomatic UTIs for women with a history of UTIs by 26%. 
   6. Treat UTIs quickly and completely. Identifying a UTI promptly and treating it in its entirety by completing the course of antibiotics even if you feel better before finishing, can prevent recurrent infections or developing antibiotic resistant bacteria. Antibiotic-resistant bacteria can make treating future infections more difficult. 

When you’re struggling with a UTI, the symptoms are hard to ignore, and it’s important to see a primary care provider as soon as you can. If you don’t have a primary care provider, Maple can help. Through our app, you can connect with a doctor or nurse practitioner online in minutes, 24/7/365 — so you don’t have to spend time wondering what your next step is. 

Dealing with a UTI is never pleasant, but being proactive can make all the difference. By recognizing symptoms early and seeking the right care, you can prevent a minor issue from escalating.

The information presented here is for educational purposes and is not meant to replace the advice from your medical professional. Virtual care is not meant for medical emergencies. If you are experiencing an emergency like chest pain or difficulties breathing, for example, please call 911 or go to your nearest emergency room.