Diabetes Insipitus Flashcards
What is diabetes insipitus?
Diabetes insipidus is a disorder characterized by deficiencyof the ADH or an abnormal response to ADH in the kidneys.
People with diabetes insipidus are unable to concentrate their urine in times of water limitations and excrete large amounts of dilute urine leaving the person with excessive thirst.
Chief manifestations of DI
excrete large amounts of urine even when they may have decreased fluid intake. The urine is very dilute and makes the person very thirsty. The dilution of the urine puts the person at risk for hypertonic dehydration and raised sodium levels if they have a lack of fluid intake.
Where is ADH made?
vasopressin is made in supraoptic nucleus. Nervous pathways which are located in the hypothalamus and run down to posterior pituitary. ADH is stored in these neural pathways and released via the PP.
How is ADH triggered?
triggered in two ways; decreased blood volume (renal perfusion) and increased osmolarity (hypothalamic Osmoreceptors_
the stored antidiuretic hormone is then discharged into the blood stream.
What is the relation between SIADH and DI
Opposite
What does ADH control
Insert water channels (aquaporons) into distal convoluted tubule and collecting ducts= INCREASE WATER RETENTION
INC thirst (hypothalamus)
Some vasoconstriction
Expected lab and urine findings in DI
Too little ADH
dilute Urine
Concentrate serum sodium
Expected findings SIADH
Too much ADH
Concentrated Urine
Dilute serum
Action of ADH on kidney
Insert water channels (aquaporons) into distal convoluted tubule and collecting ducts.
Two types of DI
Neurogenic DI (impairment of supraoptic nuclei) Nephrogenic (kidneys not responding)
Diagnosis
COMPARE
Blood Serum Osmolarity and Urine Osmolarity and ADH levels
TEST
Nephro- give artificial ADH and see if kidneys respond
Neurogenic- give hypertonic solution and measure urine output and measure ADH level
NOTE: Expected that inc Na osmolarity would cause inc in ADH secretion
Tx
Desmopressin acetate (DVAVP)
