Clinical Evaluation of Polyuria and Polydipsia Flashcards
There has to be a significant amount of what within the medulla?
UREA
The concentration gradient can be lost either through a ___________ in the tonicity of the medullary interstitum, an ____________ in the tonicity of the tubular fluid.
decrease, increase
muscle tone
tonicity
High tubular flow, high medullary blood flow, and impaired loops of Henle can all lead to the ___________________ gradient
loss of the concentration
“washed out” of solutes because of chronic severe polyuria and polydipsia for any reason, no urine concentration will occur despite the presence of endogenous vasopressin, desmopressin, and intact renal V2 receptors
Medullary Washout
High osmotic pressure of blood stimulates what?
Hypothalamus
A well-hydrated patient is NOT going to have a lot of __________ release
ADH
1° Causes: PU-Driven
* Congenital
* Acquired (Head Trauma, Brain Neoplasia, CNS Inflammation, etc.)
Central (rare) - Primary Diabetes Insipidus
1° Causes: PU-Driven
* Congenital
Nephrogenic (very rare) - Primary Diabetes Insipidus
Liver Disease (including a portosystemic shunt)
Not a lot of UREA being made
Causes: PD-Driven
- Psychogenic: behavior-driven, may be associated with stereotypic/obsessive disorders, CNS neoplasia
- Liver Disease: may be associated with hepatic encephalopathy, portosystemic shunt
Most Common Causes of PU for Dogs:
- Renal Disease
- Diabetes mellitus
- Hyperadrenocorticism
- Pyometra
- Hypercalcemia
- Psychogenic Polydipsia
- Liver Disease
Most Common Causes of PU for Cats:
- Renal disease
- Diabetes mellitus
- Hyperthyroidism
ADH Deficiency
Diabetes Insipidus
What is the next step if we ruled out everything besides psychogenic polydipsia and Diabetes Insipidus?
Water Deprivation Test
