Card Set Information
vetmed PU/PD urinary
Concentration of urine is dependent upon... (3)
presence of a conc gradient b/w lumen and renal medulla, production and release of ADH, ability of collecting duct to respond to ADH
What can disturb the conc gradient? (7)
low urea, decrease in medullary insterstitial tonicity, increase in tonicity of tubular fluid, high tubular flow, high medullary blood flow, impaired LoH, psychogenic polydipsia
Reasons for PU-driven PU/PD. (13)
chronic renal disease, liver disease, hypoadrenocorticism, hyperadrenocorticism, hypercalcemia, hyperthyroidism, DM, DI, hypokalemia, infection with E. coli, exogenous steroids, phenobarb, diuretics
Chronic renal disease causes PU/PD because of...
osmotic diuresis- loss of solutes and water
Liver disease causes PU/PD because of...
low urea, which is responsible for half the conc gradient tonicity
Hypoadrenocorticism causes PU/PD because of...
loss of medullary conc gradient (no aldosterone to increase Na+ reabsorption)
Hyperadrenocorticism causes PU/PD because of...
steroid interference with ADH
Hypercalcemia causes PU/PD because...
calcium interferes with action of ADH in tubules
Hyperthyroidism causes PU/PD because...
loss of medullary hypertonicity
DM causes PU/PD because of...
Hypokalemia cause PU/PD because of...
down-regulation of aquaporins
Primary DI causes PU/PD because...
central- failure to produce ADH, nephrogenic- inability of the collecting ducts to respond to ADH
Infections with E. coli cause PU/PD because...
endotoxin interferes with ADH
Exogenous steroids and phenobarb cause PU/PD because...
interfere with ADH
PD-driven PU/PD can be caused by...
psychogenic PD, liver disease
How does liver disease cause PD-drive PU/PD?
excess ammonia pickles the brain- hepatic encephalopathy
What are the most common causes of PU/PD in dogs? (7)
primary renal disease, diabetes mellitus, hyperadrenocorticism, pyometra, hypercalcemia, psychogenic polydipsia, and liver disease
(PK CT DRACULA is #1)
What are the most common causes of PU/PD in cats? (3)
primary renal disease, hyperthyroidism, diabetes mellitus
Client history: waxing and waning of PU/PD points to...
Any intact female dog with PU/PD should be evaluated for __________.
pyometra (spayed- stump pyometra)
__________ should be performed in all PU/PD male dogs (even neutered ones).
PU/PD patients should be evaluated for _________ trans-rectally.
anal gland adenocarcinoma--> hypercalcemia
What are the 4 steps to narrowing the differential list for PU/PD patients?
1. minimum data base
2. specific diagnostic tests
4. water dep test
Cats with PU/PD, minimum database should always include ________.
Specific diagnostic tests used to narrow differential list for PU/PD?
ACTH stim test- hyper- and hypoadrenocorticism, serum bile acids- liver disease, ionized calcium- hypercalcemia
In what patients do you perform a water deprivation test?
all other causes except DI and psychogenic PD have been ruled out
Many animals with high water intake and urine output will have ________ of their conc gradient, which may take several days to a week to restore.
Abruptly stopping all water intake may not lead to conc urine, even in patients with psychogenic PD; it may lead to...
severe and life-threatening dehydration.
If the patients has not produced conc urine after several days of reduced water intake, then...
synthetic ADH (DDAVP) is administered- if still dilute, nephrogenic; if conc, central DI
What are the end points of the water dep test, and what do they mean?
DI: patient loses >5% initial body weight, serum sodiuum and BUN increase above normal, patient becomes lethargic or ill; Psychogenic PD: USG increases to >1.030
After the water dep test,...
slowly reintroduce water to avoid water toxicity.