In Addison's disease with hyponatremia, what would you expect about serum osmolality?

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Multiple Choice

In Addison's disease with hyponatremia, what would you expect about serum osmolality?

Serum osmolality tracks the total solute concentration in the blood, with sodium playing the dominant role. In Addison’s disease, aldosterone deficiency causes salt wasting and volume depletion, and cortisol deficiency promotes ADH release. This combination leads to water retention and dilution of sodium, producing hyponatremia with a lower, or hypotonic, serum osmolality. So you’d expect a low serum osmolality. Normal or high osmolality would point to other, less typical causes of hyponatremia (such as hyperglycemia causing hypertonic hyponatremia or pseudohyponatremia), which aren’t typical in Addisonian hyponatremia.

Serum osmolality tracks the total solute concentration in the blood, with sodium playing the dominant role. In Addison’s disease, aldosterone deficiency causes salt wasting and volume depletion, and cortisol deficiency promotes ADH release. This combination leads to water retention and dilution of sodium, producing hyponatremia with a lower, or hypotonic, serum osmolality. So you’d expect a low serum osmolality. Normal or high osmolality would point to other, less typical causes of hyponatremia (such as hyperglycemia causing hypertonic hyponatremia or pseudohyponatremia), which aren’t typical in Addisonian hyponatremia.

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