Presentation

What is antidiuretic hormone (ADH) and what is its normal function?

• ADH (also called vasopressin) is released from the posterior pituitary

• Released when the body is dehydrated or hyperosmolar

• Functions to:

  • Increase water reabsorption in the renal collecting ducts

  • Decrease urine output

  • Produce small amounts of concentrated urine

• Helps maintain fluid balance, blood volume, and homeostasis

What is Diabetes Insipidus (DI)?

• A disorder of water balance, NOT glucose metabolism

• Caused by:

  • Decreased ADH production or release (central DI), OR

  • Kidney resistance to ADH (nephrogenic DI)

• Results in:

  • Large volumes of dilute urine

  • Inability to conserve water

  • Profound dehydration if untreated

What are the two main types of Diabetes Insipidus?

• Central DI

  • Insufficient ADH production or release

  • Problem in the hypothalamus or posterior pituitary

• Nephrogenic DI

  • ADH is produced normally

  • Kidneys do not respond to ADH

What are common causes of Central Diabetes Insipidus?

• Head trauma

• Brain or pituitary surgery

• Tumors (e.g., pituitary adenoma, craniopharyngioma)

• Ischemic or hypoxic brain injury

• Autoimmune or idiopathic causes

• Congenital or familial conditions

What are common causes of Nephrogenic Diabetes Insipidus?

• Chronic lithium use

• Metabolic disturbances:

  • Hypercalcemia

  • Hypokalemia

• Chronic kidney disease

• Obstructive uropathy

• Congenital genetic mutations

• Age-related decline in renal concentrating ability

What are the hallmark clinical manifestations of Diabetes Insipidus?

• Polyuria

  • 3L/day (can read 10-20L/day in severe cases)

• Polydipsia

  • Intense thirst, often for cold water

• Nocturia

• Dilute urine with low specific gravity

• Dehydration

  • Dry mucous membranes

  • Poor skin turgor

  • Weight loss

What cardiovascular and neurologic findings may be seen in DI?

• Hypotension

• Tachycardia (compensatory response to hypovolemia)

• Weak peripheral pulses

• Irritability

• Decreased level of consciousness

• Cognitive changes

• Risk of organ hypoperfusion if MAP < 65 mmHg

What laboratory patterns are characteristic of Diabetes Insipidus?

Inverse relationship between urine and blood labs

Urine (LOW):

• Low specific gravity

• Low urine osmolality

• Low urine sodium

• Low urine potassium

Blood (HIGH):

• Increased serum osmolality

• Hypernatremia

• Increased serum potassium

• Decreased total body water

What diagnostic tests are used to diagnose Diabetes Insipidus?

• Water deprivation (fluid restriction) test — gold standard

• Measures:

  • Urine output

  • Urine osmolality

  • Serum sodium and osmolality

• Desmopressin (DDAVP) response test

  • ↑ urine osmolality = central DI

  • No response = nephrogenic DI

• MRI of hypothalamus/pituitary to identify structural causes

How is Central Diabetes Insipidus treated?

• Desmopressin (DDAVP) — synthetic ADH

  • Routes: intranasal, oral, subcutaneous, IV

• Expected effects:

  • ↓ urine output

  • ↑ urine concentration

• Encourage patient to drink to thirst

• Ongoing monitoring of sodium levels

How is Nephrogenic Diabetes Insipidus treated?

• ADH is ineffective

• Treatment includes:

  • Thiazide diuretics (paradoxically ↓ urine output)

  • Low-sodium diet

  • NSAIDs (e.g., indomethacin)

  • Amiloride in lithium-induced cases

What are priority nursing interventions for a patient with DI?

• Strict intake and output monitoring

• Daily weights

• Frequent vital signs

• Assess for dehydration and fluid overload

• Monitor labs:

  • Serum sodium

  • Serum osmolality

  • Urine output and concentration

• Monitor response to DDAVP

• Maintain adequate hydration

What patient education is essential for Diabetes Insipidus?

• Understand DI type (central vs nephrogenic)

• Importance of medication adherence

• Recognize signs of:

  • Dehydration

  • Hypernatremia

  • Hyponatremia (from overcorrection)

• Maintain structured hydration routine

• Seek medical care for:

  • Vomiting

  • Fever

  • Missed doses

  • Sudden changes in urine output

What is the prognosis for Diabetes Insipidus?

• Excellent with proper management

• Most patients can live normal, active lives

• Success depends on:

  • Early recognition

  • Correct diagnosis

  • Ongoing education

  • Long-term follow-up and adherence

What is desmopressin (DDAVP)?

• A synthetic analog of antidiuretic hormone (ADH / vasopressin)

• First-line medication for central diabetes insipidus

• Mimics natural ADH to promote renal water reabsorption

How does desmopressin (DDAVP) work in the body?

• Acts on V2 receptors in the renal collecting ducts

• Increases water reabsorption back into circulation

• Decreases urine output

• Produces more concentrated urine

Which type of diabetes insipidus responds to desmopressin?

• Central diabetes insipidus ONLY

• Effective because ADH is deficient or absent

• Not effective in nephrogenic DI (kidneys do not respond to ADH)

Why is desmopressin ineffective in nephrogenic diabetes insipidus?

• ADH levels are normal

• Kidneys are resistant to ADH

• Giving synthetic ADH does not correct renal insensitivity

What routes can desmopressin be administered by?

• Intranasal

• Oral

• Subcutaneous

• Intravenous (acute or ICU settings)

What are the expected therapeutic effects of desmopressin?

• Decreased polyuria

• Decreased polydipsia

• Increased urine specific gravity

• More concentrated urine

• Stabilization of serum sodium levels

What is the most serious complication of desmopressin therapy?

• Water intoxication

• Can lead to hyponatremia

• Risk increases with excess fluid intake

What clinical signs indicate possible water intoxication from desmopressin?

• Headache

• Confusion

• Nausea and vomiting

• Weight gain

• Decreased urine output

• Seizures (severe)

What nursing assessments are critical when a patient is receiving desmopressin?

• Strict intake and output

• Daily weights

• Serum sodium monitoring

• Urine specific gravity

• Mental status changes

What patient education is essential for someone taking desmopressin?

• Take medication exactly as prescribed

• Drink fluids to thirst, not excessively

• Recognize signs of hyponatremia

• Do not skip or double doses

• Seek care during illness (vomiting, fever)