How does dehydration impact the results of blood tests?

Dehydration significantly impacts the results of blood tests by increasing the concentration of various analytes within the blood. When a person is dehydrated, the volume of plasma decreases due to fluid loss, which leads to a higher concentration of substances dissolved in the blood. This phenomenon occurs because, as water content diminishes, the same amount of solutes (like electrolytes, proteins, and waste products) is now contained in a smaller volume of fluid, resulting in elevated levels when measured.

For instance, conditions such as hemoconcentration can cause artificially high readings for analytes such as glucose, sodium, and creatinine during testing. This misrepresentation can lead to incorrect clinical assessments and management decisions, particularly if a healthcare provider interprets elevated levels as indicative of a condition when they may merely reflect the patient's hydration status. Thus, it is crucial for phlebotomists and laboratory professionals to be aware of the patient's hydration level as it can directly impact test results.