DI Flashcards
Diabetes Insipidus
Antidiuretic hormone (ADH or vasopressin) deficiency or resistance.
Pituitary/Hypothalamus causes for DI
(central type)
Autoimmune response to ADH secreting cells
Damage to the hypothalamus or pituitary stalk
Nephrogenic causes of DI
Defect in kidney tubules; kidneys fail to respond to circulating ADH
hypokalemia or hypercalcemia or hyperpararthyroidism
Certain drugs may cause this lithium, corticosteroids, DDAVP
Very rare Polydipsia two to twenty liters of fluid per day
familial?
DI
Polyuria Familial autosomal dominant DI symptoms begin at age 2
DI symptoms
Very rare, Polydipsia two to twenty liters of fluid per day, dilute urine, THIRSTY, DEHYDRATION
24 hour urine for volume and creatinine Sodium, potassium Serum osmolality HIGH
Urine osmolality LOW
Vasopressin LOW IN CENTRAL AND HIGH IN NEPHROGENIC
DI labs
DI labs
24 hour urine for volume and creatinine Sodium, potassium Serum osmolality HIGH
Urine osmolality LOW
Vasopressin LOW IN CENTRAL AND HIGH IN NEPHROGENIC
Vasopressin challenge
Urine volume for 12 hours
Desmopressin acetate is given
LOW FOR CENTRAL AND HIGH FOR NEPROGENIC
SIADH
The syndrome of inappropriate antidiuretic hormone hypersecretion (SIADH) is characterized by excessive release of antidiuretic hormone (ADH or vasopressin) from the posterior pituitary gland or another source. The result is HYPOTONIC hyponatremia and sometimes fluid overload.
if you suspect SIADH…
CT to rule out CNS d/o and CXR to rule out lung pathology
demeclocycline for what?
risks?
- for chr hyponatremia unresponsive to fluid restriction; to induce nephrogenic DI. Inhibits ADH!
- may cause neprotoxicity in pts with cirrhosis
ADH from what
pituitary hormone
SIADH found in what diseases
It is usually found in patients diagnosed with small-cell carcinoma of the lung, pneumonia, brain tumors, head trauma, strokes, meningitis, and subarachnoid hemmorhage.
SIADH
urine osmolality
urine sodium
osmolality greater than 100
sodium greater than 40
hyponatremia clinical symptoms
lethargy, disorientation, muscle cramps, anorexia, hiccups, N/V, confusion
signs of hyponatremia
HYPOreflexia, orthostatic hypoTN, cheyne stokes respirations, coma, stupor, delirium, agitation
lethargy, disorientation, muscle cramps, anorexia, hiccups, N/V, seizures
hyponatremia clinical symptoms
HYPOreflexia, orthostatic hypoTN, cheyne stokes respirations, coma, stupor, delirium, agitation
signs of hyponatremia
what can progress to seizures, coma, or brainstem herniation
hyponatremia
formula for serum osmolality
(2 x serum Na) + (BUN/2.8) + (glucose/18)
dangers of correcting hyponatremia too rapidly
central pontine myelinolysis or osmotic demyeination
? order what tests if SIADH suspected
CT and CXR
hyponatremia treatment in
1) hypervolemic & euvolemic
2) hypovolemic
1) water restriction +/- diuretics
2) Normal saline
chronic hyponatremia tx
1) rate
2) unresponsive to fluid restriction
3) euvolemic or hypervolemic hyponatremia
1) over 72 hr duration with <8 mEq/L/day
2) demeclocycline
3) vasopressin antagonists(conivaptan)
causes of DI
1) neurogenic
2) nephrogenic
3) acquired
Neurogenic: deficient secretion of ADH from pituitary
nephrogenic: kidneys unresponsive to normal vasopressin levels, inherited X linked trait,
acquired from lithium therapy, HYPOkalemia, HYPERcalcemia, or renal disease
main symptoms of DI
polyuria(50-60 mL/kg/day), nocturia, polydipsia, hypotension
maybe seizures
how to differentiate neurogenic and nephrogenic DI
Water deprivation and desmopresin testing(DDAVP):
NEUROGENIC(central) DI: dec urine output and increased urine osmolality
if little or no change in urine osmolality, it is most likely NEPHROGENIC DI
urine osmolality less than 250 mOsm/kg
despite hyperkalemia
it is NEPHROgenic DI
tx for central DI and nephrogenic DI
central: DDAVP
nephrogenic: salt restriction and water intake, thiazide diuretics
labs in volume depletion
hemocrit and serum albumin increased
urinary sodium decreases
urea increases (secondary to urine stasis in nephron) but little change in serum Cr
