Posterior Pituitary Syndromes

Question 1

What are the two most clinically significant posterior pituitary syndromes?

Answer 1

Diabetes Insipidus and SIADH

Question 2

What is SIADH?

Answer 2

Excess ADH bringing in way too much free water

Question 3

3 most common causes of SIADH?

Answer 3

Ectopic tumors releasing ADH (small cell carcinoma of the lung), Drugs, and CNS disorders including trauma and infections.

Question 4

3 clinical signs/symptoms of SIADH?

Answer 4

Hyponatremia, cerebral edema, and neurological dysfunction

Question 5

What is the problem with diabetes insipidus? What are the the two forms and explain each one?

Answer 5

ADH not doing its job for various reasons so we are losing a ton of free water. Central is a deficiency of ADH, not releasing it. So a hypo, posterior problem. Nephrogenic is that the kidneys are not responsive to ADH, have plenty of it.

Question 6

3 clinical signs/symptoms of DI?

Answer 6

Thirst, tons of urine, and increased osmolarity

Question 7

What is the test we can do to see if it is central DI or nephrogenic DI in a patient and how does it work?

Answer 7

Give DDAVP.

If patient can retain water, then it is central. If they cant retain water it is nephrogenic.

Question 8

What is the serum osmolarity for SIADH and DI?

Answer 8

Less than 3.4 and above 5.5

Question 9

What is urine osmolality for DI and SIADH?

Answer 9

Less than 50 and greater more than 1400

Question 10

Even though both DI and SIADH present with thirst, what is the catch?

Answer 10

DI actually needs to replenish fluids because you are pissing everything out.
SIADH doesn’t need to so it is inappropriate thirst.