A nurse is admitting a client who reports excessive thirst, fever, and periods of confusion. The nurse suspects the client is experiencing heat exhaustion. Which of the following electrolyte imbalances should the nurse expect?

A. Hypocalcemia: Heat exhaustion does not typically cause low calcium levels. Calcium imbalances are more often related to parathyroid disorders, vitamin D deficiency, or certain medications rather than fluid loss from heat exposure. B. Hyperphosphatemia: Elevated phosphate levels are not characteristic of heat exhaustion. Phosphate disturbances usually occur with kidney dysfunction or severe cellular breakdown, not from dehydration and electrolyte loss due to heat. C. Hyperkalemia: Potassium levels may actually decrease or remain normal in heat exhaustion due to excessive sweating and fluid loss. Hyperkalemia is not a primary concern unless there is underlying renal impairment or extensive tissue damage. D. Hypernatremia: Excessive fluid loss through sweating without adequate water replacement leads to elevated sodium levels in the blood. Hypernatremia is a common electrolyte imbalance in heat exhaustion and contributes to symptoms such as thirst, confusion, and neurologic changes.