Differential Diagnosis for Urinalysis Results

The urinalysis results provided for a female vegetarian who supplements her diet with megavitamins show several abnormalities that can guide us towards a differential diagnosis. The key findings include a dark yellow color, 1+ protein, trace blood, cloudy clarity, negative glucose, 4 EU urobilinogen, specific gravity of 1.009, negative ketones, negative nitrite, pH of 8.0, negative bilirubin, trace leukocyte esterase, 40–50 WBCs/hpf, many bacteria, and 10–12 RBCs/hpf.

• Single Most Likely Diagnosis
  • Urinary Tract Infection (UTI): The presence of many bacteria, 40–50 WBCs/hpf, and trace leukocyte esterase strongly suggests a UTI. The cloudy clarity of the urine and the trace blood also support this diagnosis. The elevated pH could be due to the infection, as some bacteria can split urea, increasing the pH.
• Other Likely Diagnoses
  • Vitamin C Interference: The discrepancy between chemical and microscopic results could be due to vitamin C (ascorbic acid) in the megavitamin supplements, which is known to interfere with urinalysis tests, potentially causing false-negative results for glucose and bilirubin.
  • Dehydration: Although the specific gravity is not very high, the dark yellow color of the urine could suggest some degree of dehydration, especially in the context of a UTI.
• Do Not Miss Diagnoses
  • Kidney Stones: The presence of blood (10–12 RBCs/hpf) in the urine could indicate kidney stones, especially if the patient has symptoms like flank pain or severe abdominal pain. This diagnosis is critical not to miss due to the potential for severe pain and complications like obstruction.
  • Pyelonephritis: An upper urinary tract infection could present with similar findings to a UTI but might also include systemic symptoms like fever, flank pain, and nausea. Missing this diagnosis could lead to more severe kidney damage.
• Rare Diagnoses
  • Tuberculosis of the Urinary Tract: Although rare, TB can infect the urinary tract and present with sterile pyuria (WBCs in the urine without bacterial growth on standard cultures), frequency, and other urinary symptoms. The presence of many WBCs and some RBCs could prompt consideration of this diagnosis, especially if standard UTI treatments fail.
  • Malignancy: Rarely, the findings could be indicative of a urinary tract malignancy, such as bladder or kidney cancer, especially if there's persistent hematuria (blood in the urine) without another clear cause.

Each of these diagnoses is considered based on the combination of chemical, microscopic, and clinical findings presented in the urinalysis results. The patient's dietary habits and supplement use also play a role in interpreting these findings.