Clinical approach to PU and PD

What is the relationship between polyuria and polydipsia

Polyuria can drive polydipsia and polydipsia can drive polyuria

What determines urine concentration

• concentration gradient between lumen and renal medulla

• production and release of ADH

• ability of tubules to respond to ADH

The concentration gradient is mostly maintained by ____________

urea

How can the concentration gradient be lost

• loss of tonicity in medulla

• increase in tonicity of tubular fluid

• increased tubular and medullar blood flow

• impaired loops of Henle

Patients with________ polydipsia can cause a medullary washout by creating high ___________

• psychogenic

• tubular flow

What are primary causes of polydipsia created by polyuria

Diabetes insipidus

Generally diabetes insipidus disturbs the body’s relationship with ___________

ADH

What are the two types of primary diabetes insipidus

• central

• nephrogenic

What type of diabetes insipidus changes the body’s ability to make or release ADH

Central diabetes insipidus

Central diabetes insipidus is ____________ or ___________ and affects the _________tissue

• congenital

• acquired

• brain

Nephrogenic diabetes insipidus is only ___________

Congenital

Nephrogenic diabetes insipidus is a genetic defect in _________ or ___________ that make them unable to respond to _________

• aquaporins

• receptors

• ADH

Secondary causes of PD caused by PU interfere with the normal process of ______________

ADH signaling

What are causes of PU that are PD driven

• psychogenic

• liver disease

Which is more common PD driven by PU or PU driven by PD

PD driven by PU

What are the most common causes of PU/PD in dogs

• renal disease

• diabetes mellitus

• cushings(hyperadrenocorticism)

• addisions(hypoadrenocorticism)

• hypercalcemia

• hyperviscosity

What are the most common causes of PU/PD in cats

• renal disease

• hyperthyroidism

• diabetes mellitus

Using the pneumonic list the common causes of PU/PD in animals

• pyelonephritis

• Hypokalemia

• hypercalcemia

• hyperthyroidism

• Diabetes mellitus

• renal failure

• addisons

• cushings

• Uterus

• liver failure

• ADH deficiency

• primary polydipsia

What steps should you follow when diagnosing an animal with PU/PD

1. minimum database

2. specific diagnostic tests

3. imaging

4. water deprivation testing

What minimum database should you gather on a dog with PU/PD

• CBC

• chemistry

• urinalysis

What would you be looking for in the CBC of an animal with PU/PD

• polycythemia

• inflammation

A dog with a USG < ____________ is more common for a polyuric presentation

1.018

What specific diagnostic tests would you run a dog presenting with PU/PD

• ionized calcium

• serum bile acids

• ACTH stimulation

• Urine culture

What imaging should be done on an animal presenting with PU/PD

• abdominal radiographs

• thoracic radiographs

• brain imaging

Abdominal radiographs and ultrasound should be focused on what structures

• kidneys

• liver

• uterus

• prostate

Thoracic radiographs on a dog presenting for PU/PD rules out what?

granulomatous disease

Water deprivation test help differentiate between what 2 conditions

• diabetes insipidus

• psychogenic polydipsia

In order to justify running a water deprivation test what must happen first

All other causes must be ruled out

An animal that undergoes a water deprivation test and cannot reestablish gradient most likely has what?

diabetes insipidus