Can a urinalysis (UA) have leukocytes and nitrite but no white blood cells (WBC) or bacteriuria?

From the Guidelines

Yes, a urinalysis (UA) can have leukocytes and nitrite but no white blood cells (WBC) or bacteriuria, as the presence of leukocyte esterase and nitrites can indicate a urinary tract infection even if WBCs or bacteria are not visible on microscopic examination. This is because leukocyte esterase detects enzymes released from white blood cells, even if intact cells are no longer present or have lysed, and nitrites indicate the presence of bacteria that convert urinary nitrates to nitrites, but these bacteria might not be visible on microscopic examination due to sampling issues, low bacterial counts, or prior antibiotic use 1.

Key Points to Consider

• The presence of leukocyte esterase and nitrites in a urinalysis can suggest a urinary tract infection, even if WBCs or bacteria are not visible on microscopic examination 1.
• The European Association of Urology guidelines recommend urinalysis, including assessment of white and red blood cells and nitrite, for routine diagnosis of urinary tract infections 1.
• Clinical correlation with patient symptoms is important for proper diagnosis and treatment decisions, as the presence of leukocyte esterase and nitrites can indicate a urinary tract infection even if WBCs or bacteria are not visible on microscopic examination 1.

Implications for Clinical Practice

• A urinalysis showing positive results for leukocyte esterase and nitrites, but no visible WBCs or bacteriuria, should be interpreted in the context of the patient's symptoms and clinical presentation 1.
• Further testing, such as urine culture and antimicrobial susceptibility testing, may be necessary to confirm the diagnosis and guide treatment decisions 1.
• The choice of antibiotic treatment should be based on local resistance patterns and optimized to ensure effective treatment of the infection 1.

From the Research

Urinalysis Results

• A urinalysis (UA) can have leukocytes and nitrite but no white blood cells (WBC) or bacteriuria, as the presence of leukocytes and nitrite does not always correlate with the presence of WBC or bacteriuria 2, 3.
• The sensitivity and specificity of WBC and nitrite in dipstick urinalysis can vary, with WBC sensitivity and specificity being 62.7% and 100%, and nitrite sensitivity and specificity being 20.6% and 93.5%, respectively 2.
• Urine culture is considered the gold standard for diagnosing urinary tract infections (UTIs), and a negative UA result does not rule out a UTI, especially in patients with a high pretest probability of UTI based on symptoms 4, 5.

Diagnostic Accuracy

• The diagnostic accuracy of urinalysis can be affected by various factors, including the patient's age, gender, and presence of underlying medical conditions such as diabetes 2, 3.
• Automated urinalysis can provide more sensitive detection of leukocytes and bacteria in the urine, but manual microscopy and urine culture may still be necessary in certain cases, such as complicated UTIs or pregnancy 3.
• The presence of nitrites in a UA can be a specific indicator of UTI, especially in elderly patients, but it is not always sensitive enough to rule out a UTI 5.

Clinical Implications

• Clinicians should interpret UA results in the context of the patient's symptoms and medical history, and consider ordering a urine culture if the diagnosis is uncertain or if the patient has a high risk of complications 4, 5.
• The choice of antibiotic treatment should be guided by the results of urine culture and sensitivity testing, as well as local patterns of antibiotic resistance 6.