Hyponatremia is one of the most common disorders identified in hospitalized patients, occurring in as many as 20-28% patients. A recent review by Lehrich et al in American Journal of Kidney Diseases discusses the role of vasopressin antagonists in treating this disorder. The following questions based on the article will test your knowledge of hyponatremia:

1. When considering a diagnosis of SIADH, which condition(s) must be excluded?

A. Decreased kidney function

B. Glucocorticoid deficiency

C. Hypothyroidism

D. All of the above

2. In patients with severe chronic (>48 hrs of onset) hyponatremia ([Na+]<105 mEq/L), what is the maximum rate of sodium correction to safely avoid neurologic sequelae when seizure or non-cardiac pulmonary edema are absent?

A. Less than 18 mEq/L over the first 24 hrs, and <22 mEq/L over the first 48hrs

B. No precautions are necessary

C. Less than 12 mEq/L over the first 24 hrs, and <18 mEq/L over the first 48hrs

D. Less than 25 mEq/L over the first 48 hours

3. What are the main physiologic stimuli resulting in arginine vasopressin (AVP) release in the posterior pituitary? (select all that apply)

A. Increased plasma tonicity

B. Decreased intravascular volume

C. Increased intravascular volume

D. Increased blood pressure

4. Which of the following diseases is NOT a contraindication to vasopressin antagonist use in hyponatremia?

A. Hypovolemic hyponatremia

B. Concomitant use of vaptans and hypertonic saline

C. SIADH

D. Severe neurologic symptoms associated with hyponatremia

5. Two common side effects of vaptan agents as reported by the SALT-1, SALT-2, and SALTWATER trials were increased thirst and dry mouth.

A. True

B. False

Post prepared by Dr. Matthew Sparks, eAJKD Advisory Board member, Duke University Medical Center.

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