Thiazide diuretic use
Na-wasting nephropathy (RTA, CKD)
Osmotic diuresis (glucose, urea)
Aldosterone deficiency
GI loss
3rd space loss
Burns
Pancreatitis
Peritonitis
Urinary Na >20
Renal failure
Urinary Na <20
Nephrotic syndrome
Cirrhosis
CHF
Renal failure
Nephrotic syndrome
Cirrhosis
CHF
SIADH
urine sodium is greater than 20-40 mEq/L
Pain, stress, nausea
Psychogenic polydipsia
Hypothyroidism
Drugs
NSAIDs, sulfonylurea, bupropion
H20 intoxication
Glucocorticoid deficiency
urine sodium is greater than 20-40 mEq/L
NSAIDs, sulfonylurea, bupropion
Hyperglycemia
Na+ decreases by 2.4mEq/L for each 100mg/dL increase in glucose over 100mg/dL
Displaced sodium in lab specimen
Hyperlipidemia
Hyperproteinemia
Na+ decreases by 2.4mEq/L for each 100mg/dL increase in glucose over 100mg/dL
Hyperlipidemia
Hyperproteinemia
Hyponatremia
Thiazide diuretic use
Hypernatremia
Na-wasting nephropathy 
Hypercapnia
Osmotic diuresis 
Hypermagnesemia
Aldosterone deficiency