Differential Diagnosis for Polyuria in a Patient Receiving Liposomal Amphotericin

• Single Most Likely Diagnosis
  • Nephrogenic Diabetes Insipidus (NDI) due to amphotericin B toxicity: Liposomal amphotericin B, despite being less nephrotoxic than conventional amphotericin B, can still cause renal impairment. NDI is a well-documented side effect, leading to polyuria due to the kidney's inability to respond to antidiuretic hormone (ADH).
• Other Likely Diagnoses
  • Hypokalemia: Amphotericin B can cause hypokalemia, which may lead to polyuria. Potassium depletion can impair the kidney's concentrating ability, resulting in increased urine output.
  • Hypercalcemia: Although less common, amphotericin B can also cause hypercalcemia, which can lead to polyuria by impairing the kidney's ability to concentrate urine.
• Do Not Miss Diagnoses
  • Acute Tubular Necrosis (ATN): While less likely than NDI, ATN is a serious condition that can occur due to amphotericin B nephrotoxicity. It requires prompt recognition and management to prevent long-term renal damage.
  • Diabetes Insipidus (Central): Although the patient is on a medication known to cause nephrogenic diabetes insipidus, central diabetes insipidus (due to a lack of ADH production) could be considered, especially if there are other symptoms suggestive of pituitary dysfunction.
• Rare Diagnoses
  • Sjögren's Syndrome: This autoimmune disorder can cause renal tubular acidosis and interstitial nephritis, leading to polyuria. However, it is less directly related to amphotericin B use compared to other options.
  • Other renal disorders: Various other renal conditions, such as polycystic kidney disease or chronic kidney disease, could potentially contribute to polyuria but are less directly linked to the use of liposomal amphotericin B.