Interpretation of fluid deprivation and desmopressin tests in polyuric patients
| Urine osmolality (mmol/kg) | Diagnosis | ||
|---|---|---|---|
| After fluid deprivation | After desmopressin | ||
| < 300 | > 750 | Cranial diabetes insipidus | |
| < 300 | < 300 | Nephrogenic diabetes insipidus | |
| > 750 | > 750 | Primary polydipsia | |
| 300–750 | < 750 | ? Partial cranial diabetes insipidus, ? partial nephrogenic diabetes, or ? primary polydipsia | |