Nō to shinkei = Brain and nerve
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The cause of hyponatremia following subarachnoid hemorrhage (SAH) has been understood as an inappropriate secretion of antidiuretic hormone (SIADH). Whereas, water restriction for the management of this condition sometimes induces a severe dehydration, resulting in vasospasm. To clarify the pathogenesis of hyponatremia following SAH, we measured the daily sodium and water balance with the plasma concentration of atrial natriuretic peptide (ANP), antidiuretic hormone (ADH), and plasma renin activity (PRA) in seventeen cases after subarachnoid hemorrhage. ⋯ These correlations suggested that hyponatremia after SAH is the result of natriuresis by an increased ANP rather than ADH. In conclusion, a greater replenishment of water and sodium is required to avoid hyponatremia with dehydration. This technique may be helpful for the prevention of vasospasms following SAH.