Differential Diagnosis for Kidney Pain

The patient presents with flank pain, feverish feelings, and a history of previous kidney infection. Here's a categorized differential diagnosis:

• Single Most Likely Diagnosis

  • Pyelonephritis (Kidney Infection): The patient's symptoms of flank pain, feeling feverish, and a history of a previous kidney infection on the left side make pyelonephritis a likely diagnosis. The increase in pain at night could be due to the body's position or increased bacterial activity.

• Other Likely Diagnoses

  • Nephrolithiasis (Kidney Stones): Although the patient denies painful urination or blood in urine, kidney stones could still be a possibility, especially if the stones are not currently obstructing the urinary tract.
  • Musculoskeletal Pain: The flank area can also be affected by musculoskeletal issues such as strained muscles or rib injuries, which could mimic kidney pain.

• Do Not Miss Diagnoses

  • Sepsis: If the kidney infection is severe and not promptly treated, it could lead to sepsis, a life-threatening condition. Early recognition and treatment are crucial.
  • Perinephric Abscess: A complication of pyelonephritis where an abscess forms around the kidney, requiring urgent medical attention.
  • Renal Infarction: A blockage of the renal arteries leading to kidney tissue death, which is rare but could present with severe flank pain and fever.

• Rare Diagnoses

  • Polycystic Kidney Disease (PKD): A genetic disorder leading to cyst formation in the kidneys, which could cause flank pain. However, it's less likely given the acute presentation.
  • Renal Cell Carcinoma: Kidney cancer could cause flank pain, but it's typically a more chronic condition and less likely to present with acute symptoms like fever.
  • Retroperitoneal Fibrosis: A rare condition where fibrotic tissue forms in the retroperitoneum, potentially encasing and obstructing structures like the ureters, leading to flank pain.