Differential Diagnosis for Urinary Pain with 3+ Leukocytes and Negative Nitrites
Single Most Likely Diagnosis
- Urinary Tract Infection (UTI) caused by an organism that does not produce nitrate reductase (e.g., Enterococcus, Staphylococcus saprophyticus): This is the most likely diagnosis given the presence of urinary pain and significant leukocyturia (3+ leukocytes), which are indicative of an inflammatory response in the urinary tract. The absence of nitrites does not rule out a UTI, as not all bacteria that cause UTIs produce nitrate reductase.
Other Likely Diagnoses
- Interstitial Cystitis: This condition, also known as painful bladder syndrome, can cause urinary pain and frequency without a significant bacterial infection, potentially leading to a negative nitrite test. Leukocytes may be present due to the inflammatory nature of the disease.
- Urethritis: Inflammation of the urethra can cause urinary pain and leukocyturia. The absence of nitrites suggests that the infection might not be due to the typical nitrate-reducing bacteria.
- Prostatitis: In men, prostatitis can cause urinary pain and significant leukocyturia. The negative nitrite test does not rule out this diagnosis, as prostatitis is often caused by bacteria that do not produce nitrate reductase.
Do Not Miss Diagnoses
- Tuberculosis of the Urinary Tract: Although rare, urinary tuberculosis can cause chronic urinary pain, leukocyturia, and a negative nitrite test. It's crucial to consider this diagnosis to avoid missing a potentially serious and treatable condition.
- Kidney Stones with Infection: The presence of a kidney stone can cause obstruction and subsequent infection, leading to urinary pain and leukocyturia. The absence of nitrites does not rule out this diagnosis, and it's critical to identify and treat any underlying infection and obstruction.
- Malignancy of the Urinary Tract: Although less common, urinary tract malignancies can cause urinary pain and leukocyturia. A negative nitrite test does not exclude this diagnosis, and further investigation is necessary to rule out cancer.
Rare Diagnoses
- Schistosomiasis: This parasitic infection can cause urinary symptoms, including pain and leukocyturia, particularly in individuals who have traveled to or lived in endemic areas. The negative nitrite test does not rule out this diagnosis.
- Malacoplakia: A rare inflammatory condition that can affect the urinary tract, causing urinary pain and leukocyturia. It is often associated with chronic infection and can present with a negative nitrite test.
- Foreign Body in the Urinary Tract: Although rare, the presence of a foreign body in the urinary tract can cause inflammation, leading to urinary pain and leukocyturia, with a negative nitrite test if there is no associated bacterial infection that produces nitrate reductase.