The laboratory features are identical to those of SIADH, with euvolemic hyponatremia, plasma hypo-osmolality, and increased urinary osmolality.

The polyuria is clear, equal to or greater than 500 ml / 24 hours, and reaches 1 to 21/24 hours in the infant, with normal density of less than 1005 and urinary osmolality between 50 and 100 mmol / kg.

The polyuria is clear, equal to or greater than 500 ml / 24 hours, and reaches 1 to 21/24 hours in the infant, with normal density of less than 1005 and urinary osmolality between 50 and 100 mmol / kg.

The maximum urinary osmolality is then compared to the urinary osmolality obtained after injection of pitressin or dDAVP.

These authors consider that the urinary osmolality of the affected patients is fixed, their urine flow is directly correlated with the osmotic load.

Several conditions can cause high urine osmolality, including:

Several conditions may cause low urine osmolality, including:

In rare cases, high urine osmolality can occur due to Addison’s disease.

Both high and low urine osmolality have several causes.