A kidney infection, a serious urinary tract infection (UTI), affects one or both kidneys. This condition arises when bacteria, typically from the bladder, travel upwards to infect the kidneys. Kidney infections are more severe than lower UTIs and require prompt medical attention to prevent complications. Accurate diagnosis is important for effective treatment and to safeguard kidney health.
Initial Doctor’s Evaluation
A suspected kidney infection begins with a doctor’s evaluation of symptoms and a physical examination. Patients commonly report fever, chills, and pain in the lower back or side, sometimes radiating towards the groin. Other symptoms include painful urination, frequent or urgent need to urinate, nausea, vomiting, and a general feeling of being unwell. These symptoms help doctors suspect a kidney infection.
During the physical exam, the doctor checks for tenderness in the costovertebral angle (CVA), an area on the back formed by the twelfth rib and the spine, directly overlying the kidneys. Tenderness elicited by gentle tapping or pressure in this region, referred to as CVA tenderness, often suggests inflammation or swelling of the kidney, a common sign of a kidney infection. This finding, combined with symptoms, guides further diagnostic testing.
Laboratory Diagnostics
Laboratory tests confirm a kidney infection and identify the specific bacteria responsible. Urinalysis is a common initial test where a urine sample is examined for infection indicators. White blood cells (leukocytes) in the urine often suggest infection, as they are part of the body’s immune response. Red blood cells may also be found, indicating irritation or damage to the urinary tract.
Specific chemical markers like nitrites and leukocyte esterase are also sought. Nitrites are byproducts created when certain bacteria convert nitrates into nitrites, strongly suggesting a bacterial infection. Leukocyte esterase is an enzyme produced by white blood cells, indicating an inflammatory response. While these findings point to infection, a urine culture and sensitivity test is performed for a definitive diagnosis.
A urine culture involves growing bacteria from the sample to identify the exact microorganism. This test also determines the bacteria’s sensitivity to various antibiotics, ensuring the most effective medication is prescribed. This approach ensures effective treatment and helps prevent antibiotic resistance.
Blood tests may also be ordered, including a complete blood count (CBC) to check for an elevated white blood cell count, a general sign of infection. Kidney function tests, such as creatinine and blood urea nitrogen (BUN), assess how well the kidneys filter waste. These are important if there are concerns about severity or kidney impact.
Imaging for Diagnosis
While laboratory tests often suffice for straightforward kidney infections, imaging studies are important in certain situations. Imaging is considered if the infection is severe, recurrent, not responding to treatment, or if an underlying structural problem is suspected. These tests visualize the kidneys and surrounding structures for detailed assessment.
Ultrasound is a non-invasive technique using sound waves to create images of the kidneys and bladder. It can detect signs of infection like swelling, fluid collection, or abscesses. Ultrasound also identifies blockages, such as kidney stones, or other structural abnormalities that might predispose to recurrent infections. It is safe and radiation-free.
A computed tomography (CT) scan provides more detailed cross-sectional images of the kidneys and urinary tract. CT scans can identify complications like kidney abscesses, obstructions, or other anatomical issues contributing to the infection. Sometimes, a contrast dye is injected to enhance visibility of structures and delineate inflammation. Magnetic Resonance Imaging (MRI) is less common for initial diagnosis but may be used when detailed soft tissue imaging is needed or radiation avoided.
Understanding Your Diagnosis
The diagnostic process integrates findings from the doctor’s evaluation, laboratory tests, and, when necessary, imaging studies. Doctors review symptoms, physical findings like CVA tenderness, and urinalysis and urine culture results. A positive diagnosis confirms the presence of a kidney infection, often identifying the specific bacterial culprit and its susceptibility to various antibiotics.
This information helps determine infection severity and if underlying conditions, like kidney stones or structural abnormalities, contribute. This understanding allows for a tailored treatment plan. Prompt treatment based on an accurate diagnosis is important to resolve the infection, alleviate symptoms, and prevent serious complications such as permanent kidney damage or the spread of infection to the bloodstream.