Differential Diagnosis for 24 YOF with Progressive Onset of Flank Pain, Polyuria, Fever, Nausea, and Vomiting

• Single Most Likely Diagnosis
  • Pyelonephritis: This is the most likely diagnosis given the combination of flank pain, fever, and positive dipstick leukocytes, which indicate a urinary tract infection (UTI) that has ascended to the kidneys. The presence of polyuria could be due to an associated cystitis or the body's attempt to flush out the infection.
• Other Likely Diagnoses
  • Kidney Stones (Nephrolithiasis): The flank pain and nausea/vomiting could be indicative of kidney stones, especially if the stones are obstructing the flow of urine, which could also lead to infection. However, the presence of leukocytes and fever leans more towards an infectious process.
  • Dehydration: Possibly contributing to or exacerbating the symptoms, especially given the nausea, vomiting, and polyuria. However, dehydration alone would not account for the positive leukocytes.
• Do Not Miss Diagnoses
  • Sepsis: Although less likely given the information, any infection (like pyelonephritis) can potentially lead to sepsis, a life-threatening condition that requires immediate intervention. The presence of fever and systemic symptoms (nausea, vomiting) warrants consideration of sepsis.
  • Diabetic Ketoacidosis (DKA): The presence of ketones in the urine, along with polyuria, could suggest DKA, especially if the patient has undiagnosed diabetes. DKA is a medical emergency and must be considered, even though the primary symptoms suggest a urinary issue.
• Rare Diagnoses
  • Tubulointerstitial Nephritis: An inflammation of the tubules and interstitial tissue of the kidneys, which could present with similar symptoms but is less common and might not initially present with such a clear infectious picture.
  • Renal Infarction: Although rare, especially in a young female without a history of thrombophilic disorders or vascular disease, it could present with acute flank pain and systemic symptoms. However, this would not typically cause a positive dipstick for leukocytes or ketones.