2026 HESI Gerontology Practice Test – Comprehensive All-in-One Guide for Age-Related Risks Case Study Success!

In older adults, the level of sodium in the blood mainly reflects water balance. When fluid intake is poor, especially in the context of limited access to fluids, impaired thirst, or cognitive/functional limitations, a water deficit develops faster than sodium stores. This concentrates sodium in the blood, leading to hypernatremia. Elderly individuals are particularly at risk because they may not drink enough due to forgetfulness, depression, or dependence on caregivers for fluids, so dehydration becomes common and hypernatremia follows.

Hyponatremia would require relatively more water intake or problems with salt handling, which isn’t the typical pattern with simply poor intake. Hyperkalemia and hypocalcemia are not directly caused by inadequate intake alone; they stem more from renal function, hormonal regulation, medications, or bone and vitamin D status. So the rise in serum sodium from reduced water consumption makes hypernatremia the most common disturbance in this scenario.