Dr. Greene’s Answer:
Fever, back pain, and bacteria in the urine means that the urinary tract infection is not just in the bladder (cystitis) but also in the kidney (pyleonephritis). When blood is still present (called hematuria), it is important to find out what it looks like and why it is there. Urinary infections themselves can cause blood in the urine and the blood typically resolves as the infection resolves. There are several other causes for blood in the urine of a child, including kidney stones. A stone or a “pre-stone,” called hypercalciuria (too much calcium in the urine) can cause blood and pain.
About 5 to 10 percent of all kidney stones happen in kids. One bacterium that causes urinary infections (proteus) is also prone to cause stones. At a minimum, boys with this type of infection need a renal ultrasound and a VCUG (an x-ray taken during urination). If there is suspicion of a stone or hypercalciuria, then a blood test for calcium, phosphorus, uric acid, electrolytes, and parathyroid hormone should be performed. Further tests could include kidney studies (CT scan, ultrasound, and/or X-rays), urine for calcium:creatinine ratio, and a 24-hour urine collection to measure the total amount of calcium. This test isn’t performed for infections, but it is done to check for stones.