Pathology Which of the following would help to differentiate between SIADH and psychogenic polydipsia? A Blood urea nitrogen (BUN) 16 mg/dL B Serum osmolality 265 mOsm/L C Serum potassium 4 meq/L D Urine osmolality 500 mOsm/L 💡 Explanation Which of the following would help to differentiate between SIADH and psychogenic polydipsia? ✓ Correct Answer: D. Urine osmolality 500 mOsm/L