NurseSavvy Cheat SheetDisease
Diabetes Insipidus
Pathophysiology & Risk Factors
Diabetes insipidus (DI) is an ADH problem, not a glucose problem. Either the posterior pituitary makes too little ADH (central DI) or the kidneys cannot respond to it (nephrogenic DI). Without ADH effect, the collecting ducts stay impermeable to water, so the body dumps massive volumes of dilute urine and loses free water — driving serum sodium and osmolality up.
Signs & Symptoms
EarlyProgresses →
polyuria Hallmark
4-20 L/day of dilute urinepolydipsia Hallmark
intense, insatiable thirstpale colorless urine
Late / Severe
dehydration
poor skin turgor, dry mucous membranestachycardia
hypotension
restlessness
neuro change from hypernatremiaDiagnostics & Labs
DI vs SIADH — the ADH discriminator
Diabetes InsipidusSIADH
ADH effectdeficient / no effectexcess
Urinelarge volume, dilute, low specific gravityscant, concentrated, high specific gravity
Serum sodiumhypernatremiahyponatremia
Fluid statusdehydration / hypovolemiafluid retention
Treatmentdesmopressin (central)fluid restriction
Diabetes Insipidus
- ADH effect
- deficient / no effect
- Urine
- large volume, dilute, low specific gravity
- Serum sodium
- hypernatremia
- Fluid status
- dehydration / hypovolemia
- Treatment
- desmopressin (central)
SIADH
- ADH effect
- excess
- Urine
- scant, concentrated, high specific gravity
- Serum sodium
- hyponatremia
- Fluid status
- fluid retention
- Treatment
- fluid restriction
Interventions & Priorities
strict hourly intake and output
in acute DIreplace fluids to match output Hallmark
prevents hypovolemic shockdaily weights
monitor serum sodium and osmolality
assess for dehydration
skin turgor, HR, BP, neuro statusTreatments & Medications
desmopressin (DDAVP) Hallmark
central DI only; intranasal or oralthiazide diuretic
nephrogenic DI; paradoxically reduces urine outputlow-sodium diet
nephrogenic DItreat underlying cause
Patient Teaching
take desmopressin at consistent times
prevents breakthrough polyuriado not stop desmopressin when output normalizes
controls symptoms but does not cure DIweigh daily
report gain > 2 lb in 24 hoursdrink to thirst, do not force fluids
forcing fluids on DDAVP risks hyponatremiawear medical identification
report return of thirst or polyuria
signals underdosingReport Nowescalate immediately
urine output > 200 mL/hr with specific gravity < 1.005> 200 mL/hr & SG < 1.005
signals developing DI; not self-limitinghypernatremia with neuro changes
restlessness, altered mental statushypovolemic shock
hypotension, tachycardia from unreplaced lossesrapid weight gain with hyponatremia on desmopressin
DDAVP overtreatment / water intoxication; hold dose and notify providerClinical Pearl
DI is "drying out" — Dilute urine, Insatiable thirst, high sodium. ADH is the body's water-saving valve; in DI the valve is stuck open. (SIADH is the mirror image.)