Nejm 2000;342:1493

Cause:

• Central diabetes insipidus (Diabetes Insipidus (Central and Nephrogenic))
• Nephrogenic DI (Diabetes Insipidus (Central and Nephrogenic)), including drug induced by lithium, demeclocycline (Declomycin), foscarnet
• Dehydration from
• Inability to drink
• Betadine rx of burns
• Diminished urine concentration and diminished thirst in elderly (Nejm 1984;311:753), esp when have adult onset diabetes, leading to nonketotic hyperosmolar coma (Nejm 1977;297:1452)

Most common in infants and debilitated elderly

Sx:Confusion

Si:Confusion, stupor, coma; hypotension, dehydration

Mortality >40% in elderly (Ann IM 1987;107:309); seizures

Lab: Chem:Na >150 mEq/L or >300 mOsm/L, measured or calculated (Osmolarity)

Rx:

Acutely replace water, but not faster than 12 mEq/24 h (brain swelling), w D₅W, 1/4 normal saline (0.225%), or 1/2 normal saline (0.45%); water deficit calculation (24 Hour Requirements)

Chronically rx w thiazides and/or carbamazepine, which increase renal sensitivity; or vasopressin nasal or im (Diabetes Insipidus (Central and Nephrogenic))