Diabetes Insipidus

1. Diabetes Insipidus Cindy A. Fehr Malaspina University-College BSN Program NRSG 335 Fall 2005

3. Renal Failure Reviewed • Acute Renal Failure • When kidneys fail suddenly • Function usually returns to normal if renal system supported, sometimes require dialysis in short-term • Chronic Renal Failure • Slow & progressive deterioration of kidney function • Usually irreversible; when nephrons stop working • Causes  diabetes, HTN • When functioning reaches < 10-20% normal rate  called End Stage Renal Disease  dialysis or transplantation required

4. Renal Failure Reviewed • ADH • Produced in hypothalamus & stored in posterior pituitary • Causes fluid retention or lack of diuresis • Also known as vasopressin in large amounts  constricts arterioles • Released in response to  circulating volume (dehydration,  plasma osmolality, hypotension, hypoxia associated with hypovolemia raises ADH release) • Acts by conserving H2O to  blood volume & BP & return serum osmolality to normal

5. Diabetes Insipidus • Definition • lack of ADH production or release or use, depending on type of DI • Characteristics– regardless of cause, S&S same • polyuria (excessive dilute urination) > 2L/day • Polydipsia • If left untreated  changes in LOC, tachycardia, tachypnea, hypotension (shock-like symptoms), but unlike hypovolemic shock, u/o  • Can lead to hypernatremia  restlessness, agitation,  deep tendon reflexes, seizures • Prevention • No specific preventive measure for initial disturbance • Prevention of repeat occurrences by treating, preventing cause

6. Diabetes Insipidus-Types • Neurogenic/Central DI • d/t insufficient amounts ADH  synthesis, transportation, release • hypothalamus doesn’t produce enough ADH or posterior pituitary doesn’t release ADH • Most frequently seen • Causes – anything that can affect brain’s ability to release ADH • Congenital • CNS disorders – tumors (pituitary or brain), infections • Cerebrovascular disease or cerebral trauma • Well recognized complication of closed head injury • Cerebral surgery near the hypothalamohypophysial tract • pregnancy

7. Diabetes Insipidus-Types cont. • Nephrogenic DI • inadequate renal response to ADH • ADH produced normally but distal tubules & collecting ducts can’t respond to hormone’s signal to reabsorb H2O • ADH levels normal or high • Collecting ducts don’t  permeability in response to ADH • Causes • Congenital; genetics; familial • Renal obstruction or damage (pyelonephritis, polycystic disease, amyloidosis) • Chronic kidney disease or end organ failure • Medications (lithium, demeclocycline, anesthetic methoxyflurane) that damage renal tubules (reversible) • Severe electrolyte disturbances • Idiopathic with abrupt onset

8. Diabetes Insipidus-Types cont. • Psychogenic DI • uncommon • Causes • Psychogenic disorders or disorders associated with abnormal thirst • Eg. Water intoxication disorder which is associated with schizophrenia

9. Patients at Risk of DI • Head injuries • Neurosurgery • Pituitary tumors • Inflammation or infection of brain tissues • Those taking medications that inhibit AHD release or action on kidneys • Ethanol • Glucocorticoids • Adrenergics • Phenytoin • Opiod antagonists • Lithium ****

10. insufficient ADH What HappensDuring DI immediate excretion large volumes dilute urine & urine specific gravity low Unconscious Patients  plasma osmolality Conscious Patients Thirst mechanism stimulates polydipsia Fluid ingestion< requirements Fluid ingestion= or > loss Fluid ingestion< requirements Hypernatremia Dehydration

11. Signs & Symptoms • Change in mentation • Insomnia • Excessive thirst – polydipsia • Weight loss • Urinary frequency – polyuria – 4-18 L/day • Nocturia • Skin, mucous membranes cool • Low urine osmolality; low urine specific gravity • High normal plasma osmolality after 8 hrs H2O deprivation (keep in mind plasma osmolality always higher than urine)

12. Diagnostics • Correlating clinical presentation with serum osmolarity • Plasma ADH levels • Water deprivation test • Dangerous because can cause those with DI,  vascular volume  circulatory collapse & shock • Without DI  rapid  urine volume • With DI  no  urine volume & urine osmolality 100 mOsm/kg • ADH test • Differentiates between neurogenic and nephrogenic DI • Challenged with ADH (usually DDAVP intranasally) & u/o measured before & after DDAVP administration • Neurogenic DI  kidneys respond by concentrating urine • Nephrogenic DI  kidneys can’t concentrate urine

13. Treatment Options • Depends on cause and severity of disorder • Neurogenic DI • Based on extent of ADH deficiency, age, endocrine and cardiovascular status, lifestyle variables • If symptomatic  u/o > 9L/day & urine osmolality < 100 mOsm/kg after dehydration or water restriction test • ADH replacement (synthetic vasopressin analog DDAVP – desmopressin, either po or intranasally) • Why intranasally? • No effect on smooth muscle, won’t  BP, less likely to cause arrhythmias • Must monitor for fluid overload and hyponatremia • Chlorpropamide (also helps  thirst) • Carbamazepine (similar effects to chlorpropamide) • Indapamide (similar effects to thiazide diuretics) • IM pitressin or Pituitrin (bovine extract with oxytocin & vasopressin) with less side effects • Vasopressin IV in emergency situations

14. Treatment Options • Nephrogenic DI • Kidneys don’t respond to ADH • Do not respond to pharmacologic preparations of hormone • Low salt diet • May respond partially to thiazide diuretics which  Na excretion by kidneys   GFR &  reabsorption of H2O in proximal tubule rather than collecting duct (which is under ADH influence for H2O reabsorption) • Incomplete ADH Deficiency • Can maintain normal or near normal water balance when permitted to drink water in response to thirst • Drugs that potentiate action of otherwise insufficient amounts endogenous ADH • Chlorpropramide • Thiazide diuretics

15. Treatments Goals • Assess, identify and begin treatment early • Identify underlying cause/disorder & treat • Balance fluid intake with output • Acute cases  rapid fluid replacement • Chronic cases  slow replacement to prevent cerebral edema • Replacement of ADH (IV, subcutaneous, intranasal) with DDAVP (desmopressin acetate) Sometimes need to remove pituitary gland • Medications to stimulate production of ADH &  symptoms aggravating process • Daily weights, accurate in/out, urine specific gravity, osmolality • Age & culturally appropriate information