Polydipsia and Polyuria

neuronal irritation (pathologic thirst cause)

(hypothalamic) 1. tumor 2. trauma 3. inflammation

fluids

are complicated must add electrolytes otherwise diluting the body need extra by maintanance when replacing _________

pd and pu

both appear consistently in several polysystemic disorders. these diseases manifest in a disorder in water homeostasis

SG over 1.035

can concentrate their urine has to be something else

hypercalcemia (disorders causing pu)

cancer inhibition of ADH then mineralization of the kidney -> chronic renal failure

hypercalcemia (pathologic thirst cause)

cancer kidney dz lung tissue (mineral formation)

azotemic

cant get rid of toxins in the urine cause halitosis

renal disease (disorders causing pu)

decrease renal concentration mechanisms

Renin and Angiotensin

dipsenogenic compounds -compounds that stimulate thirst by direct action on neurons in thirst center -certain diseases cause an increase in ______ and/or ____________

Water Deprivation tests

dont do if animal is azotemic, dehydrated or hypercalcemic. used to R/o primary pd 1. 12 hour fast - blood serum osmolality, obtain SG evaluate 3-4 hours 2.terminate when concentrated urine is produced, weight loss of 7% or more occurs or there is increase in plasma protein/osmolality 3. failure to concentrate: -ADH deficiency -ADH unresponsiveness -Primary renal disease -medullary washout

polydipsia

excessive thirst persisting for long periods of time. Constant drinking abnormally excessive drinking

main treatment

fluids spiked 1st with dextrose -boost of energy -help them pee -if dont pee then kidneys shut down -start up the kidneys

Isosthenuric

glomerular filtrate with a specific gravity equal to plasma which is 1008 to 1012 urine is more concentrated than glomerular filtrate abnormality not as [ ] as should be -> renal problem

hyperadrenocorticism (disorders causing pu)

increased production of glucocorticoids ADH inhibition at the collecting ducts cushings-pendullus abd, bilateral allopeica, blackmarks, v, pu, pd, older animals

Iatrogenic

induced by humans usually drug induced

diabetes mellitus (disorders causing pu)

insulin deficiency -hyperglycemia -> glucosuria (profile) causing increased absorbable solute can test with dipstick

Antidiuretic hormone control center

lies adjacent to the thirst center this center is controlled by extracellular fluid osmolality

Countercurrent system (RCM)

loops of Henle water is reabsorbed along [ ] gradients established in the renal medulla -> this dec osmolality

medullary washout (disorders causing pu)

loss of countercurrent multiplier system chronic renal disease

diuretic

make urinate mannitol dextrose furosemide (lasix) osmotic diuresis

polyurias

many diseases produce ___________ by affecting renal concentrating mechanisms or by stimulating primary polydipsia

Pseudopsychogenic polydipsia (disorders causing pu)

not common primary polydipsia compensatory polyuria

secondary thirst (pd)

not well understood -anticipates water needs prior to actual deficiences -more common cause of Pd

2nd basic principle

overhydration vs. dehydration (intracellular)

Pathologic thirst

primary polydipsia (not compensatory) caused by: 1. neuronal irritation 2. compulsive water drinking 3. increased plasma renin 4. hypercalcemia 5.thoracic calval constriction

compulsive water drinking (pathologic thirst cause)

pseudopsychogenic polydipsia caused by: anxiety boredom compulsive, neurotic owners

brain trauma

put animal on diuretic to relieve pressure in the brain caused by fluid mannitol is small and can pass through the blood brain barrier furosemide is too large and cant get out of the system

polyuria & polydipsia disorders

several disorders produce pu and pd by disturbing distal and collecting tubular function

hydration status

tent the skin hematocrit PCV

polyuria

the passage of a large volume of urine in a given period. Usually urine has a decreased SG abnormally excessive urination

physical exam

thorough/complete weight, hydration status, CBC, profile, UA, plasma proteins specific gravity >1.005 is NOT pu measure water consumption

pyometra (disorders causing pu)

tubule unresponsive to ADH uterus full of pus

diabetes insipidus (disorders causing pu)

two types -neurogenic- neural injury causing def of ADH -nephrogenic- tubule enzyme def causing unresponsiveness to ADH loops of henle change permiability when bound - cant bind

1st basic principle

water in = water out acohol alcohol

primary thirst (pd)

well understood -intracellular dehydration -left atrial volume and pressure receptors - 8-10% decreases in blood volume induces thirst it is not a primary mechanism that determines water intake -> stimulates ADH/thirst center

ADH Vasopressin Response Test

when animals fail to [ ] urine obtain urine SG, withhold water and food, give SQ vasopressin tannate. Take urine SG at 30 min SG of >1.015 are normal failure to respond indicates primary renal disease, diabetes insip, or MW

kidney enzymes

BUN/ CREAT increased -usually indicate renal problem or enzyme in blood incidating some cell death -how can you tell how bad the problem is? ultrasound, rads, palp, UA, further tests, KIDNEY BIOPSY

diseases that cause pu by affecting RCM/stim 1st pd

1. diabetes insipidus 2. diabetes mellitus 3. hyperadrenocorticism 4. hypercalcemia 5. hyperthyroidism 6. liver failure 7. medullary washout 8. pyometra 9. pseudopsychogenic polydipsia 10. renal disease 11. iatrogenic

Diagnostic plan

1. document the problens of pu and pd exist - owners can mislead 2.Data base -> clues for diagnosis 3. perform urine concentration test 4. special diagnostic testing *also tissue sampling kidney tests/ exploratory surgeries *usually small animals have primary pu with compensatory pd

Urine Concentration test

1. water deprivation tests 2.ADH vasopressin Response test

Renal concentrating mechanism

25 lb dog -> 68 liters of fluid are filtered by the glomeruli each day but less than 500 ml is excreted as urine 1. ADH osmoreceptor control system 2. countercurrent system

ADH osmoreceptor control system (RCM)

ADH- produced by specialised neuorns stored in nerve endings - (hypothalamus-piticulocytes-nerve endings) inc extracellular fluid osmolality -> inc ADH release -> inc collecting tube permeability -> water to be reabsorbed

polydipsia, polyuria

______________ usualy results from primary _____________

thirst

a desire for water controlled in the hypothalamus/ stimulus to drink

iatrogenic (disorders causing pu)

alcohol causes inhibition of ADH release (dec nerve function) glucocorticoids - ADH inhibition - diuretic effect