By Jennifer Kearney-Strouse
Urinalysis can be a helpful tool, but it can’t tell you everything. At a Friday morning session at Internal Medicine Meeting 2026, Jasmine Marcelin, MD, FACP, offered her thinking on the test for the audience of internal medicine physicians.
When a urinary tract infection (UTI) is suspected, positive nitrites, for example, are relatively specific but not very sensitive on urinalysis (UA), while positive leukocyte esterase is relatively sensitive but not very specific, explained Dr. Marcelin, who is an associate professor in the division of infectious diseases at the University of Nebraska Medical Center in Omaha.
“Other things can cause elevated or positive leukocyte esterase, especially if a person has other comorbidities, different issues that might be affecting the renal system, and if people are dehydrated,” she said. “There's a lot of different reasons why people can have an elevated leukocyte esterase.”
Similarly, be careful interpreting pyuria in UTI diagnosis, Dr. Marcelin advised. “Pyuria is the one that trips us up a lot, because it feels like there should not be white blood cells in urine, especially when we think about how the urine is filtering and where things are going,” she said. “But the fact is that pyuria represents inflammation, but not always infection.”
Pyuria does have very good negative predictive value, so if it’s not there the likelihood of a UTI is low, but the positive predictive value is below 15%, making it a factor to be considered but not relied on, she noted.
She suggested thinking of pyuria the way you would inflammatory markers in the blood. While erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) level can raise concern for infection, she said, “we feel generally comfortable saying or acknowledging that ESR and the CRP could also be elevated for other reasons.”
Bacteriuria, while common, especially in older adults and patients with catheters, does not by itself always indicate infection, Dr. Marcelin said. The same goes for foul-smelling cloudy urine.
“If I asked in this room, ‘How many folks have had a presentation where somebody described foul-smelling urine?,’ almost everybody would raise their hands,” she said. “The thing is that foul-smelling urine is alarming, but there is no clinical correlation between foul-smelling urine and accurate diagnosis of a urinary tract infection.”
All of this might raise the question of when to get a urinalysis, and Dr. Marcelin had some tips on that as well.
“You should get a UA if a person has genitourinary symptoms, so dysuria, frequency, urgency, suprapubic pain. You should get a UA if a person is presenting with systemic signs of infection, like fever, hypotension, et cetera, without an alternative cause that is immediately identified,” she said.
Conversely, she said, do not routinely perform urinalysis in older adults who present with altered mental status and falls without urinary symptoms, in hospitalized patients with fever or hypotension who have clear alternative sources of infection, or for routine workup of a fever in patients without genitourinary symptoms.
Finally, asymptomatic patients, with or without an indwelling catheter, should not receive routine urinalysis, but there are two populations where such screening is called for: “Pregnancy and [prior to] invasive urologic procedures where you're going to have mucosal barrier breakage,” Dr. Marcelin said. “Those are the ones where you want to screen asymptomatic individuals.” ■