The Diagnostic Value of Urinalysis in Hemodialysis Patients with Fever, Sepsis or Suspected Urinary Tract Infection

Prevalence and Significance of Pyuria in Chronic Kidney Disease Patients in Saudi Arabia

Chronic kidney disease (CKD) is considered a major health problem, which poses a burden for health care systems worldwide. It has been estimated that 10% of the population worldwide have CKD; however, most of the cases are undiagnosed. If left untreated, CKD could lead to kidney failure, which highlights the importance of early diagnosis and treatment. Pyuria has been reported in CKD patients, and could be the result of several comorbidities, such as diabetes, or urinary tract infections (UTIs). A few studies have shown that pyuria is associated with the late stages of CKD. However, there are limited data on the prevalence of non-UTI (sterile) and UTI-pyuria in different CKD patient populations, and its association with the decline in kidney function and progression of CKD. In this retrospective study, we report the prevalence of pyuria (sterile and UTI) in 754 CKD patients of King Fahd Specialist Hospital, Buraydah, Saudi Arabia. Our data showed that 164/754 CKD patients (21.8%) had pyuria, whereas 590 patients (78.2%) presented with no pyuria. There was a significantly higher percentage of late-stage (stage 4) CKD patients in the pyuric group compared to the non-pyuric group (36.6% vs. 11.9%). In line with the previous data, proteinuria was detected in a significantly higher percentage of pyuric patients, in addition to significantly higher levels of serum creatinine and urea, compared to non-pyuric patients. Furthermore, 13.4% of the pyuric CKD patients had UTI, whereas 86.6% presented with sterile pyuria. E. coli was indicated as the causative agent in 45.5% of UTI patients. Our patient data analysis showed that a significantly higher percentage of UTI-pyuric CKD patients, than sterile pyuric patients (63.6% vs. 19.7%), had higher numbers of urinary white blood cells (>50/HPF, WBCs). The data also showed that a higher percentage of UTI-pyuric patients were late-stage CKD patients, compared to sterile pyuric patients (50% vs. 34.5%). Our findings indicate that a high level of pyuria could be considered as a marker for late-stage CKD, and that UTI is an important risk factor for the decline in kidney function and the progression to late-stage CKD. We believe that further studies are needed to correlate pyuria to kidney function, which could be helpful in monitoring the progression of CKD. Moreover, the management of comorbidities, such as diabetes and UTIs, which are risk factors for CKD and associated pyuria, could help to control the progression of CKD to the late stages.

Prevalence and Clinical Characteristics of Asymptomatic Pyuria in Chronic Kidney Disease

Background

Pyuria seems to be common in chronic kidney disease (CKD), irrespective of urinary tract infection (UTI). It has been hypothesized that sterile pyuria occurs in CKD because of chronic renal parenchymal inflammation. However, there are limited data on whether CKD increases the rate of pyuria or how pyuria in CKD should be interpreted. We investigated the prevalence and characteristics of asymptomatic pyuria (ASP) in CKD via urinary white blood cell (WBC) analysis.

Methods

Urine examination was performed for all stable hemodialysis (HD) and non-dialysis CKD patients of the outpatient clinic (total N=298). Patients with infection symptoms or recent history of antibiotic use were excluded. Urine culture and WBC analysis were performed when urinalysis revealed pyuria.

Results

The prevalence of ASP was 30.5% (24.1% in non-dialysis CKD and 51.4% in HD patients). Over 70% of the pyuria cases were sterile. The majority of urinary WBCs were neutrophils, even in sterile pyuria. However, the percentage of neutrophils was significantly lower in sterile pyuria. In multivariate logistic regression analysis, the degree of pyuria, percentage of neutrophils, and presence of urinary nitrites remained independently associated with sterile pyuria.

Conclusions

The prevalence of ASP was higher in CKD patients and increased according to CKD stage. Most ASP in CKD was sterile. Ascertaining the number and distribution of urinary WBCs may be helpful for interpreting ASP in CKD.