First Things First (assess & treat for the following)

• Water & sodium disorders CANNOT be separated from each other.
• Any statement concerning regulation of water will involve disturbance of sodium concentration & vice versa.
• Regardless of the current sodium concentration, symptomatic fluid deficits (hypovolemia) should be corrected urgently using an isotonic fluid such as lactated Ringer’s or normal saline.
• The cause of DI is lack of ADH (central DI) or lack of ADH effect (nephrogenic DI).
• Virtually any CNS disorder can lead to central or neurogenic DI.
• If pt is taking lithium (or has anytime, especially if recently), then the pt has a component of DI (lithium-induced nephrogenic DI [LINDI]).
• The “classic” findings include polydipsia, polyuria (>30 mL/kg/d), volume depletion & hypernatremia, w/ hyperosmolar serum despite hypo-osmolar urine.