Which statement describes hyponatremia in endocrine disorders most accurately?

Which statement describes hyponatremia in endocrine disorders most accurately?

• A. Severe symptomatic hyponatremia should be treated exclusively with fluid restriction.
• B. SIADH causes hypervolemic hyponatremia that responds to diuretics alone.
• C. SIADH causes euvolemic hyponatremia and is treated with fluid restriction; hypothyroidism and adrenal insufficiency can contribute; severe symptomatic hyponatremia may require hypertonic saline.
• D. Hyponatremia due to endocrine disorders is always due to dehydration and should be treated with hypotonic fluids.

Answer: (C)

In endocrine-related hyponatremia, the classic scenario is SIADH, where excessive ADH causes the kidneys to retain free water. This dilutes serum sodium but usually leaves the patient euvolemic (not fluid-overloaded and not dehydrated). The best initial management is fluid restriction, which limits free water intake and allows the excess water to be excreted, gradually raising the sodium level. Hypothyroidism and adrenal insufficiency can contribute to hyponatremia by impairing water excretion and promoting ADH release, so addressing the underlying endocrine issue is important. When hyponatremia becomes severe with symptoms like seizures or altered mental status, you don’t rely on fluid restriction alone. Hypertonic saline is used to raise the serum sodium more rapidly but carefully, to avoid overcorrection and potential brain injury. The other statements are off the mark because SIADH does not cause hypervolemia and typically does not respond to diuretics alone; the condition is euvolemic and fluid restriction is the standard approach. And hyponatremia from endocrine disorders is not simply dehydration needing hypotonic fluids—hypotonic fluids would worsen the dilutional hyponatremia and are not the correct initial strategy.

In endocrine-related hyponatremia, the classic scenario is SIADH, where excessive ADH causes the kidneys to retain free water. This dilutes serum sodium but usually leaves the patient euvolemic (not fluid-overloaded and not dehydrated). The best initial management is fluid restriction, which limits free water intake and allows the excess water to be excreted, gradually raising the sodium level. Hypothyroidism and adrenal insufficiency can contribute to hyponatremia by impairing water excretion and promoting ADH release, so addressing the underlying endocrine issue is important.

When hyponatremia becomes severe with symptoms like seizures or altered mental status, you don’t rely on fluid restriction alone. Hypertonic saline is used to raise the serum sodium more rapidly but carefully, to avoid overcorrection and potential brain injury.

The other statements are off the mark because SIADH does not cause hypervolemia and typically does not respond to diuretics alone; the condition is euvolemic and fluid restriction is the standard approach. And hyponatremia from endocrine disorders is not simply dehydration needing hypotonic fluids—hypotonic fluids would worsen the dilutional hyponatremia and are not the correct initial strategy.