Polyuria/Polydipsia
what is another name for hyperadrenocorticism?
Cushing's disease
what are symptoms of cushings disease?
bilateral alopecia, pendulous abdomen, Pu/Pd
what does hypercalcemia indicate?
cancer or cushings
how does pyometra lead to PuPd?
causes the tubules to be unresponsive to ADH
what are diuretics?
chemicals that enhance urinary output
what is thoracic caval constriction?
constriction of the vena cava in thorax
how does renal disease cause PuPd?
decreases renal concentration mechanisms
how do you perform the water deprivation test?
deprive the animal of water for 12 hours and measure urine SG every 3-4 hours; terminate if urine is concentrated, weight loss of 7% or more occurs, or increase in plasma protein or osmolality
what is thirst?
desire to drink
what should be included in treatment for kidney failure?
dextrose
what are some disorders that cause Pu/Pd?
diabetes insipidus, diabetes mellitus, hyperadrenoncorticism, hypercalcemia, hyperthyroidism, liver failure, medullary washout, pyometra, renal disease, iatrogenic diseases
what are renin and angiotensin?
dipsinogenic molecules that stimulate thirst
what are the 4 steps of diagnostic plan for PuPd?
document that issues of PuPd exit, data base collection, perform urine concentration tests, perform special diagnostic tests
if presenting PuPd what may be seen on an ultrasound?
enlarged pelvic area
what is polydipsia?
excessive thirst
what is polyuria?
excessive urination
what controls the ADH control center?
extracellular fluid osmolality
what SG would indicate a kidney issue?
greater than 1.035
what causes primary polydipsia?
hypothalamic irritation, compulsive water drinking or pseudopsychogenic polydipsia, increased plasma renin, hypercalcemia, thoracic caval constriction
where is the thirst center located?
hypothalamus
when should a ADH response test be performed?
if the animal fails to concentrate their urine during the water deprivation test
when should you not perform a water deprivation test?
if the animal is azotemic, dehydrated or hypercalcemic
what does iatrogenic mean?
illness or disease caused by humans or drug induced
what is the function of antidiuretic hormone?
increase water reabsorption to concentrate urine
what is the ADH osmoreceptor control system?
increased extracellular osmolality leads to ADH release causing increased collecting tubule permeability for increased water resorption
what would you use diuretics to treat?
inflammation
how does hypercalcemia cause PuPd?
inhibits ADH and mineralizes kidneys causing chronic renal failure
how does alcohol cause PuPd?
inhibits ADH release
what is diabetes mellitus?
insulin deficiency
what causes primary thirst?
intracellular dehydration and low blood volume and pressure detected by left atrial receptors
how does hyperadrenocorticism cause Pu/Pd?
it causes an increased production of glucocorticoids which inhibit ADH recognition at collecting duct
how does diabetes mellitus cause Pu/Pd?
it causes hyperglycemia leading to glucosuria
what is the common name for furosemide?
lasix
what is medullary washout?
loss of countercurrent multiplier system
does the urine of polyuric animals have a high or low specific gravity?
low
what diuretic would be choice for cerebral edema?
mannitol
what are common diuretics?
mannitol, dextrose, furosemide, alcohol
what causes thoracic caval constriction?
mass putting pressure on vena cava
what is the neurogenic cause of diabetes insipidus?
neural injury to pituitary gland causes a deficiency of ADH
what diseases cause ADH deficiency?
neurogenic diabetes insipidus, iatrogenic causes
what are the two causes of diabetes insipidus?
neurogenic or nephrogenic
are animals with SG >1.035 poly uric?
no
is secondary thirst well understood?
no
how do you perform a ADH response test?
obtain urine SG withhold water and food, give SQ injection of vasopressin tannate, take urine SG at 30 min
does polyuria or polydipsia cause the other?
polydipsia is usually a result of primary polyuria
what is pseudopsychogenic polydipsia?
primary polydipsia caused by stress, anxiety, boredom leading to compensatory polyuria
what is pathologic thirst?
primary polydipsia that causes compensatory polyuria
what is pyometra?
pus in the uterus
what does dipsinogenic mean?
quality of compounds that stimulate thirst by direct action on the thirst center
what are common dipsinogenic compounds?
renin and angiotensin
what are pituicytes?
specialized neurons that produce ADH
what does isosthenuric mean?
specific gravity of glomerular filtrate is equal to plasma meaning urine is more concentrated than glomerular filtrate
what is secondary thirst?
the animal anticipates its water needs prior to deficiencies so it drinks a lot in preparation
what does a positive vasopressin response test indicate?
the animal has a ADH deficiency or unresponsiveness
what does a failure to obtain concentrated urine from a water deprivation test indicate?
the animal has an ADH deficiency, ADH unresponsiveness, primary renal disease or medullary washout
what does a failure to respond to the vasopressin response test indicate?
the animal has primary renal disease, diabetes insipidus or medullary washout
what is the water deprivation test used for?
to rule out primary polydipsia
what is the nephrogenic cause of diabetes insipidus?
tubule enzyme deficiency causing an unresponsiveness to ADH
what is another name for antidiuretic hormone?
vasopressin
what are some urine concentration tests?
water deprivation test and ADH response test
what is the countercurrent system?
water is reabsorbed along concentration gradients found in the loop of henle in renal medulla causing decreased osmolality
what should be included in a physical exam of a dog with suspected PuPd?
weight, hydration status, PCV, plasma proteins, urine SG
what is medullary wash out?
worn out kidneys
what is the SG of plasma?
1.008-1.012
what is a normal SG in response to the vasopressin response test?
1.015
what is a dog's normal SG?
1.020-1.025
what is a cat's normal SG?
1.025-1.030
how much fluid can a 25# dog's glomeruli process each day?
68 liters
how much of a blood volume decrease stimulates thirst?
8-10% decrease
how much urine would a 25# dog produce in a day?
<500ml
how do glucocorticoids cause PuPd?
ADH inhibition
what are some renal concentrating mechanisms?
ADH osmoreceptor control system and countercurrent system
what is the abbreviation for polyuria and polydipsia?
Pu/Pd
what is diabetes insipidus?
a disorder caused by inadequate amounts of ADH which causes excessive water loss
where is the antidiuretic hormone control center?
adjacent to the thirst center in the hypothalamus
what are some iatrogenic causes of PuPd?
alcohol, glucocorticoids, diuretics
