Hyponatremia in pregnancy is not uncommon, but may on occasion be severe enough to warrant a thorough evaluation and intervention. In a recent case published in AJKD, Pazhayattil and colleagues report a relatively rare cause of hyponatremia and discuss the diagnostic and therapeutic approach to this tricky problem, which can have serious consequences if unrecognized. The following questions based on the article will test your knowledge on this topic.

1. A 10% reduction in effective circulating fluid volume is required before AVP release is stimulated.

A. True
B. False

2. A fall in serum sodium concentration of ~5 mEq/L and serum osmolality of ~10 mmol/kg occurs early in pregnancy, and nadir at about 8-10 weeks gestation. The cause(s) of this physiologic change include (choose one or more answer):

A. Pregnant women are thirsty and ingest more water than solutes, resulting in hyponatremia
B. Hyponatremia is an artifact, and the true serum sodium concentration in pregnancy is normal
C. Hyponatremia is the result of a reset osmostat for AVP release
D. Hyponatremia is due to non-osmotic release of AVP due to arterial underfilling
E. Increased vasopressinase activity from the placenta results in a breakdown of AVP

3. The treatment of choice for transient diabetes insipidus of pregnancy is:

A. AVP
B. Desmopressin
C. Tolvaptan
D. Demeclocycline
E. Either desmopressin or AVP

4. Euvolemic hypotonic hyponatremia in pregnancy can be caused by reset osmostat, true SIADH, and nephrogenic syndrome of antidiuresis (NSIAD). NSIAD is characterized by (choose one or more answers):

A. Release of AVP at lower sodium concentration than normal, resulting in hyponatremia
B. Elevated and non-suppressible AVP concentrations, with high urine osmolality
C. Is an inherited condition with variable manifestations in females
D. Results from a constitutionally activated V2 receptor, with high urine osmolality even in the absence of AVP secretion

Post prepared by Dr. Swapnil Hiremath, eAJKD Contributor.

To see the answers, please click here.

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