Osmolality	Volume	Urine	Cause
Low <275	⤵️	Na <40	Salt loss (Vomiting, Diarrhea, Dehydration
		Na >40	RENAL SALT LOSS (Diuretics? Adrenal insufficiency?)
	ⓝ	Osm <100	Psychogenic Polydipsia
		Osm >100	SIADH
	⤴️	ø	CHF / Hepatic failure / Nephrotic Syndrome
ⓝ	ø		Pseudohyponatremia (⤴️ Lipids, Proteins)
High >295			Hyperglycemia

Mild	Moderate	Severe
Asx	Minimal confusion	Coma, Sz
Restrict fluids	Saline / Loop diuretics	HYPERTONIC SALINE

	SIADH
?	·       CNS insult of any kind ·       Medications (Carbamazepine, SSRIs, NSAIDs) ·       Lung disease (PNA) ·       Ectopic ADH secretion (SCLC)
S/S	·       Hyponatremia: Severe: SZ, coma, AMS ·       Euvolemia (Moist mucous membranes, no edema, no JVD)
Dx	·       Hyponatremia ·       Serum osmolality <275 (hypotonic) ·       Urine osmolality >100 ·       Urine sodium >40
Tx	Fluid restriction ± salt tablets Hypertonic (3%) saline for severe hyponatremia

	Iatrogenic Hyponatremia
RF	·       Hypotonic fluid hydration ·       Children, premenopausal women, elderly ·       Hypoxia ·       CNS Disorders
S/S	·       Headache ·       N/V ·       Encephalopathy (AMS, SZ)
Tx	·       Hypertonic (3%) saline ·       Serial measurement of electrolytes ·       Increase serum sodium 6-8 in first 24hrs