A Stepwise Approach To PU/PD

Question 1

How do we ensure the presence of PU/PD?

Answer 1

• History
• Measurement of water intake at home
• USG

Question 2

This is complete or partial deficiencies in arginine vasopressin (AVP)

Answer 2

Central Diabetes Insipidus

Question 3

What is nephrogenic diabetes insipidus?

Answer 3

Decreased action of AVP within the kidneys

Question 4

What finding on USG would you expected with PU/PD?

Answer 4

Marked hyposthenuria (SG < 1.006)

Question 5

If you do a modified deprivation water test, what will you see with primary PD?

Answer 5

Increase in urine specific gravity in response to water restriction alone

Question 6

If you do a modified deprivation water test, what will you see with central diabetes insipidus?

Answer 6

Increased in urine specific gravity after administering DDAVP

Question 7

If you do a modified deprivation water test, what will you see with primary nephrogenic diabetes insipidus?

Answer 7

Lack of response to DDVAP

Question 8

How is a DDVAP trial ran?

Answer 8

Therapy is administered over 5-7 days and response assessed with changes in water intake

Question 9

If you do a DDAVP trial, what will you see with primary nephrogenic diabetes insipidus and primary polydipsia?

Answer 9

Dog will fail to respond

Question 10

If you do a DDAVP trial, what will you see with central diabetes insipidus ?

Answer 10

Dog will have a dramatic decrease in water intake and increase in USG

Question 11

What are some differentials for primary polydipsia?

Answer 11

• Physiologic response
• Behavioral
• Other medical conditions: hyperthyroidism, fever, GI disease, neurologic disease

Question 12

What are differentials for primary polyuria?

Answer 12

Diabetes insipidus, osmotic diuresis, and misc

Question 13

This is the ingestion of excess water resulting in compensatory polyuria to prevent water intoxication

Answer 13

Psychogenic polydipsia