From the Guidelines
Diabetes insipidus is characterized by hypernatremia, increased serum osmolality, and inappropriately dilute urine with low urine osmolality, typically <200 mOsm/kg H2O, as noted in a recent expert consensus statement 1. The most prominent lab values associated with diabetes insipidus include:
- Hypernatremia (serum sodium >145 mEq/L)
- Increased serum osmolality (>295 mOsm/kg)
- Inappropriately dilute urine with low urine osmolality (<200 mOsm/kg H2O) despite the presence of hypernatremia, as recommended for diagnosis by a recent consensus statement 1
- Increased urine output, often exceeding 3-4 liters per day (polyuria) These laboratory findings reflect the underlying pathophysiology of diabetes insipidus, which involves either inadequate production of ADH by the hypothalamus (central) or kidney resistance to ADH (nephrogenic), resulting in the body's inability to conserve water appropriately, as supported by a strong recommendation to suspect diabetes insipidus in children with polyuria, polydipsia, failure to thrive, and hypernatraemic dehydration with inappropriate low urine osmolality 1. Key diagnostic features of diabetes insipidus, as outlined in recent guidelines, include:
- Serum sodium levels
- Serum osmolality
- Urine osmolality
- Urine output The diagnosis of diabetes insipidus should be suspected in patients with polyuria, polydipsia, failure to thrive, and hypernatraemic dehydration, with a comprehensive diagnostic work-up including measurement of serum sodium, serum osmolality, and urine osmolality, as recommended by recent expert consensus statements 1.
From the FDA Drug Label
For injection use only. Diabetes Insipidus: Laboratory tests for monitoring the patient include urine volume and osmolality In some cases, plasma osmolality may be required.
The lab values commonly seen with diabetes insipidus include:
- Urine volume: to monitor the patient's response to treatment
- Urine osmolality: to assess the concentration of the urine
- Plasma osmolality: may be required in some cases to evaluate the patient's hydration status and response to treatment 2 3
From the Research
Lab Values in Diabetes Insipidus
Lab values commonly seen in diabetes insipidus include:
- Hypernatremia (elevated serum sodium levels) 4, 5
- High serum osmolality (greater than 300 mOsm/kg) 6, 5
- Low urine osmolality (less than 200 mOsm/kg) 6, 5
- Polyuria (excessive urine production) 7, 4, 8, 5
- Undetectable or low arginine vasopressin (AVP) levels 5
- Elevated blood urea nitrogen (BUN) and serum calcium levels may also be present in some cases 6
Specific Lab Values
Some specific lab values mentioned in the studies include: