Adjustment of the osmostat in primary aldosteronism.

OBJECTIVE

To analyze osmoregulation in primary aldosteronism.

DESIGN

The physiologic and pathologic factors involved in function of the osmostat and in hypernatremia were reviewed.

RESULTS

Patients with primary aldosteronism commonly have mild hypernatremia, with serum sodium concentrations usually less than 150 meq/L. Hypernatremia has been detected in patients with aldosterone-producing adrenal adenomas and adrenal hyperplasia. The patients seem to ingest normal amounts of water. Adjustment of the osmosta (in the hypothalamus) to a higher than normal level of plasma osmolality seems to be the cause. Resetting of the osmostat to a higher level has rarely been noted in conditions other than primary aldosteronism. The hypernatremia can be corrected by either medical or surgical treatment of the primary aldosteronism.

CONCLUSION

Mild hypernatremia in primary aldosteronism is attributable to shifting of the osmostat to the right.