Final answer:
Hypersecretion of aldosterone can cause increased sodium and water retention, leading to hypernatremia and high blood pressure, which matches Avery's medical condition.
Step-by-step explanation:
The hypersecretion of aldosterone could lead to Avery's condition of high blood pressure and hypernatremia. Aldosterone is a hormone produced by the adrenal cortex that regulates sodium concentrations and blood volume, primarily by stimulating sodium and water reabsorption in the kidneys. This process increases the concentration of sodium ions in the blood, which can lead to hypernatremia. Additionally, as more water is retained, blood volume and blood pressure rise. Aldosterone secretion can be stimulated by various factors including low blood sodium levels, low blood pressure, low blood volume, or high blood potassium levels. Its overproduction can therefore lead to the retention of sodium and water, raising blood volume and exacerbating hypertension.