Water Balance and diabetes Flashcards
When is present if you see concentrated urine?
ADH
What if you see dilute urine?
ADH is absent
What is the diluting portion of the nephron
thick ascending limb
What is the concentrating potion of the nephron
thick ascending limb
Where can you make the choice to get rid of water
End of Distal convoluted tubule
What allows for water to be drawn out other than ADH?
medullary interstitum hypertonicity
AND ADH required
What sets up hypertonicity
passive thin ascending loop NaCl movement
active NKCC2 in thick ascending loop
Urea transport UTA1 in collecting duct
How is the thin ascending loop able to still move sodium out
Presence of urea helps you have a larger gradient difference
What does ADH increase
Water AND Urea permiability
ADH-UT-A1
(ADH-AQP2)
What does someone on loop diuretics need to do?
measure sodium and water intake because they cannot concentrate/dilute urine
If urine osmolarity is greater than plasma, what would you expect?
Free water clearance is negative
retention
If urine osmolarity is less than plasma, what would you expect?
Free water clearance is positive
excretion
What is someones Free water clearance on loop diuretics
0
Where is AVP made
hypothalamus in supraoptic nuclei
Where is AVP secreted
posterior pituitary
What does AVP activate
V2 which activates cAMP and in turn AQP2 and UTA1
V1 which causes platelet aggregation (vasoconstictor)
Where does AVP work
Only from Collecting duct on
What controls urine water excretion
osmoreceptors in the 3rd ventricle
What states cause nonosmotic release of AVP
hypotension
hypovolemia
(caused by ATII)
What disease has too little ADH activity
diabetes insipidus
What is seen in too much ADH
too much water causing hypernatremia
SIADH
What causes central Diabetes insipidus
deficient ADH secretion
What causes nephrogenic diabetes insipidus
decreased sensitivity of kidney to ADH
What do you use for central diabetes insipidus
Desmopressin (V2 selective)
intranasally
What is desmopressin used in
central diabetes insipidus
nocturnal enuresis
von Williebrand disease
What do you have to watch when taking desmopressin
water intake
What would you see in nephrogenic diabetes insipidus
elevated AVP levels
What is gestational diabetes insipidus
placental vasopressinase causes low serum AVP
What is primary polydipsia
disorder of excess fluid ingestion
How do you treat nephrogenic diabetes
Thiazide diuretics
How do thiazides help nephrogenic diabetes
They prevent the thirst by getting rid of excess sodium
What antagonizes V2
Tolvaptan
What antagonizes V1 and V2
Conivaptan
What can be used in SIADH and CHF to protect against electrolyte imbalance
Tolvaptan
What can lithium carbonate cause
nephrogenic diabetes insipidus
What can demeclocycline cause
nephrogenic diabetes insipidus (same as lithium but less toxic)
