Approach to PU PD Flashcards
Define polyuria.
Urine production >50 ml/kg/day
Define polydipsia.
Water intake >100 ml/kg/day
Define isosthenuria.
USG 1.008-1.012
Define hyposthenuria.
USG 1.001-1.007
Define minimally concentrated.
USG < 1.030 for dogs and <1.035 for cats
Define dysuria.
Difficult urination
Define stranguria.
Straining to urinate
Define pollakiuria.
Increase frequency of urination
What are differentials for hyposthenuria?
Hyperadrenocorticism
E. coli infection
Psychogenic polydipsia
Central diabetes insipidus
Nephrogenic diabetes insipidus
Hepatic insufficiency
What is ADH released in response to?
Increased plasma osmolality and volume depletion
What is the mechanism for pu/pd with diabetes mellitus? How would you diagnose it?
Osmotic diuresis due to glucosuria
Dx: blood glucose, urine glucose
What is the mechanism for pu/pd with renal failure? How would you diagnose it?
Osmotic diuresis of remnant nephrons + structural disruption of medullary concentration gradient
Dx: BUN, creatinine, SDMA, urinalysis
What is the mechanism for pu/pd with bacterial pyelonephritis? How would you diagnose it?
Renal parenchymal damage + E. coli endotoxin competes with ADH on renal tubules
Dx: Urine culture, abdominal ultrasound, excretory urogram
What is the mechanism for pu/pd with hypercalcemia? How would you diagnose it?
Inhibits binding of ADH to receptors on renal tubules
Dx: Serum or plasma calcium
What is the mechanism for pu/pd with hyperadrenocorticism? How would you diagnose it?
Glucocorticoids inhibit ADH release and inhibit effect of ADH on renal tubules
Dx: LDDST, ACTH stimulation test, urine cortisol:creatinine ratio
What is the mechanism for pu/pd with hyperthyroidism? How would you diagnose it?
Increased medullary blood flow + psychogenic
Dx: serum T4
What is the mechanism for pu/pd with hepatic insufficiency? How would you diagnose it?
Loss of medullary concentrating gradient (low urea), possibly psychogenic
Dx: Chem panel, bile acids, blood ammonia, abdominal imaging
What is the mechanism for pu/pd with pyometra and E. coli septicemia? How would you diagnose it?
Endotoxin competes with ADH binding sites on renal tubules
Dx: History, CBC, abdominal imaging, cultures
What is the mechanism for pu/pd with post-obstructive diuresis? How would you diagnose it?
Osmotic diuresis due to retained solutes (especially urea)
Dx: history, urine output
What is the mechanism for pu/pd with hypoadrenocorticism? How would you diagnose it?
Mineralocorticoid deficiency results in sodium loss + renal medullary washout
Dx: Serum Na+ and K+, ACTH stimulation test
What is the mechanism for pu/pd with diabetes insipidus? How would you diagnose it?
Primary: decreased ADH production
Nephrogenic: defect in renal response to ADH
Dx: modified water deprivation test and diagnosis of exclusion
