Significance of C-reactive Protein Levels in Categorizing Upper and Lower Urinary Tract Infection in Adult Patients

Urinary tract infections (UTIs) are one of the most commonly encountered infections in outpatients. The distinction between upper UTI and lower UTI is significant as it has therapeutic and prognostic importance. The accurate diagnosis of UTI, especially its anatomical location, is essential for administering anti-microbial therapy successfully. Plasma levels of C-reactive protein (CRP) increase 1,000-fold during bacterial infections. Elevated CRP levels are often seen in acute pyelonephritis and rarely in cystitis. Therefore, this study aimed to evaluate the diagnostic role of serum CRP in upper and lower UTI in adult patients along with correlating its role in UTI patients.

The study included 81 patients who were >18 years old, diagnosed with UTI by microbiological culture and ultrasonography of the pelvis. Demographic data along with findings of the systemic examination, complete blood count, random blood sugar, urine analysis, and CRP levels of all patients were recorded. Data were analyzed using R Studio.3.5.3 software, and a p-value ≤ 0.05 was considered significant.

The prevalence of UTI was higher among females (60.49%). About 53.09% of patients exhibited upper and 46.91% exhibited lower UTI. The prevalence of Escherichia coli was higher among cases of both upper (88.37%) and lower (65.79%) UTI. The most common final diagnosis in upper UTI patients was acute pyelonephritis (90.7%) and that in lower UTI was cystitis (65.79%). The difference in the CRP levels between the upper and lower UTI patients was significant (p=0.02). Thirty-four patients had CRP levels >100 mg/L, all exhibiting upper UTI.

About 53.09% of patients exhibited upper UTI and were diagnosed with acute pyelonephritis. A significant increase in the CRP levels in upper UTI can help determine the anatomical location and can help in targeting effective management of the infection by anti-microbial therapy.