The Frequency of Leukocytes and Nitrites in the Urine of Healthy Adults
Conditions: Asymptomatic Bacteriuria, Asymptomatic Pyuria
Sponsor: Kendall Healthcare Group, Ltd.

 
 
Urinalysis Results in Healthy Individuals 
 
NCT04055675 
 
July 19, 2019 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 
 
 
 
 
 
Introduction: 
 
The urinalysis (UA) is one of the most commonly utilized tests in the emergency department 
(ED) [1].  In some busy EDs, a UA is routinely ordered by protocol on patients with abdominal 
pain, and in elderly patients, a UA is often ordered for a variety of chief complaints including 
dizziness and altered mental status.  When these patients, who often do not specifically have 
symptoms of a urinary tract infection, have a urinalysis demonstrating pyuria or bacteriuria, it 
may be interpreted as an atypical presentation of a UTI.  However, it is possible that these 
patients do not have urinary tract infections, but have baseline pyuria or bacteriuria.  One prior 
study found that 5% of sexually active healthy women 18-40 have asymptomatic bacteriuria [2], 
and the rate of asymptomatic bacteriuria increases with age, such that it is present in 8-10% of 
women from 70-80 years of age [3].  Moreover, one prior article stated that 30-50% of residents 
of long term nursing facilities have positive urine cultures at any given time [4].   
 
The above statistics come from the results of urine cultures.  In the ED, the decision to treat or 
not treat a patient for a UTI is not made based upon culture results, but upon a urinalysis 
(microscopic or dipstick).  To our knowledge, only one prior study has looked at the frequency 
of abnormal urinalyses in healthy individuals, and it found that over a third of asymptomatic 
women had at least 1+ leukocytes in their urine [5].  This is evidence that a substantial number of 
people who do not have symptomatic UTIs have UAs that could be interpreted as UTIs.  If these 
results could be replicated and expanded to include a wider group of individuals (males, elderly 
patients, various races, etc.), it would provide valuable information about how we can better 
interpret and utilize the results of a UA. 
 
Thus, we propose a prospective study to assess the frequency of abnormal UAs in a wide variety 
of individuals without acute symptoms. 
 
Methods: 
 
This will be a prospective, observational study of subjects over the age of 18.   
 
Any person over the age of 18 who is able to spontaneously provide a urine sample may be 
included.  Exclusion criteria include any acute symptoms, active vaginal bleeding or abnormal 
discharge, pregnancy, prisoner status, antibiotics within the last 72 hours, or urologic procedure 
within the last week.  Patients will be sampled from volunteers in the community. 
 

 
 
All volunteers will sign a written consent, approved by the IRB. The consent form discusses the 
risks and benefits of our study.  
 
The patient will fill out a brief data collection form to include their age, gender, weight, race, 
whether or not they reside in a long-term nursing facility, and chronic medical problems,.  
 
Urine will be collected by all subjects by midstream clean-catch technique after receiving 
standardized verbal and written instructions.  In particular, female subjects will be instructed on 
how to provide a mid-stream sample:  void initially in the toilet, then spread the labia to collect a 
sample.  We won’t mandate perineal cleansing as that has not been shown to decrease perineal 
flora contamination [6].   
     
While some EDs use microscopic UAs to evaluate for UTIs, urine dipstick (Mission Urinalysis 
Reagent Strips) has been compared to microscopic testing in many prior studies [7,8,9,10,11].  
Some show microscopic tests to be a bit more accurate [8,9,10], while others find similar 
accuracies [7,11].  Overall, urine dipstick is thought to have a very high sensitivity for UTI 
[12,13,14], and for the simplicity of this study, we will only use urine dipstick results to 
determine if a patient has a UTI. 
 
Subjects will void into a sterile cup.  While wearing gloves, the research assistant will place the 
dipstick such that all markers are immersed in the urine for 3 seconds.  The urine will be 
analyzed after 2 minutes (as per manufacturer instructions).  
 
The definition of a positive urinalysis is variable in the literature.  These studies define a positive 
UA as having at least 1+ leukocytes or any nitrite [5, 15], while other studies have defined a 
positive UA as having any leukocyte or nitrite [8, 12].  As a means to not overestimate the rate of 
positive UAs in asymptomatic individuals, we will define a positive UA as one in which the 
dipstick shows at least 1+ leukocytes or positive nitrites. 
 
The patient will be informed of the results of their UA, but since all patients in this study will 
have no acute symptoms, no patients will be treated with antibiotics.  If there is an abnormal 
result (such as hematuria or proteinuria), the patient will be counselled to follow up with a 
primary care doctor. 
 
The primary outcome for this study is the overall frequency of urine dipsticks that are positive 
(as defined above) in subjects without symptoms of a UTI.  Secondarily, we seek to determine if 
the frequency of positive UAs varies based on gender, age, chronic medical problems, or living 
facility.  Multivariate linear and logistic regressions will be performed to determine if certain 
factors are associated with an increased risk of pyuria or urinary nitrites.          
 

 
 
In order to protect the privacy of the research subjects and to maintain the confidentiality of the 
data, all data will be handled only by research staff.  No protected health information will be 
collected except on the consent form, which will be stored separately from the data collection 
form.  
 
We intend to enroll 200-300 healthy volunteers.   
 
 
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