required according to the treating physician 16:00 serum osmolality, U+Es (± copeptin) In the setting of ongoing severe polyuria, more frequent checks of serum osmolality, electrolytes and renal function may be required according to the treating physician Termination serum osmolality, U+Es (± copeptin) - Urine osmolality plateaus (i.e. <30 mOsm/kg increase between two consecutive hourly measurements). This indicates maximal urinary concentrating ability - Weight loss of more than 3% of baseline weight - Serum sodium levels > 150 mmol/L - Urine osmolality > 800mOsm/kg IV 2 g DDAVP 1 hour post Weight, BP, HR Patient to limit fluid intake to 500-800ml DDAVP serum osmolality, U+Es (copeptin) for next 24 hrs if urine concentrated post urine osmolality, sodium DDAVP INTERPRETATION: Primary Nephrogenic Complete Partial Central polydipsia Diabetes Central Diabetes Diabetes Insipidus Insipidus Insipidus Baseline 5 21.4 < 2.6 < 5 ≥ copeptin (pmol/L) < 300 > 300 > 300 > 300 Serum osmol (mOsm/kg) Urine osmol > 800 < 300 < 300 300-800 (300 800 if (mOsm/kg) – chronic) Post DDAVP < 10% < 50% > 50% 10-50% urine osmol Rise (%) Figure: Diagnostic algorithm for the differential diagnosis of the polyuria-polydipsia syndrome (3)
required according to the treating physician 16:00 serum osmolality, U+Es (± copeptin) In the setting of ongoing severe polyuria, more frequent checks of serum osmolality, electrolytes and renal function may be required according to the treating physician Termination serum osmolality, U+Es (± copeptin) - Urine osmolality plateaus (i.e. <30 mOsm/kg increase between two consecutive hourly measurements). This indicates maximal urinary concentrating ability - Weight loss of more than 3% of baseline weight - Serum sodium levels > 150 mmol/L - Urine osmolality > 800mOsm/kg IV 2 g DDAVP 1 hour post DDAVP Weight, BP, HR serum osmolality, U+Es (copeptin) urine osmolality, sodium Patient to limit fluid intake to 500-800ml for next 24 hrs if urine concentrated post DDAVP INTERPRETATION: Primary polydipsia Nephrogenic Diabetes Insipidus Complete Central Diabetes Insipidus Partial Central Diabetes Insipidus Baseline copeptin (pmol/L) 5 ≥ 21.4 < 2.6 < 5 Serum osmol (mOsm/kg) < 300 > 300 > 300 > 300 Urine osmol (mOsm/kg) > 800 (300 – 800 if chronic) < 300 < 300 300-800 Post DDAVP urine osmol Rise (%) < 10% < 50% > 50% 10-50% Figure: Diagnostic algorithm for the differential diagnosis of the polyuria-polydipsia syndrome (3)