While a blood test is simple for you—with the exception of feeling "a little pinch"—the actual diagnostic process behind the scenes is quite complex, requiring specialized equipment and technicians. Even before your blood is tested, it needs to be properly prepared for the analyzer. It might be spun very fast to separate the blood cells from the fluid portion of the blood, creating a serum or plasma sample. Then the blood analyzer device counts and identifies the shape and size of blood cells, or measures chemical reactions to detect concentrations of certain molecules in blood. Finally, the results are verified by a trained lab professional and returned to your doctor.
Sodium balance is tightly regulated to avoid extreme variations in concentration, which can disrupt normal cell function. Osmolarity is the process of controlling the amount of soluble substances per volume. Balancing sodium input and output with water plays a central role in maintaining osmolarity. When you become dehydrated, your body must conserve water and excrete sodium to prevent the sodium concentration from increasing. When you have excess water, your body retains sodium and excretes water to prevent sodium dilution. Balancing sodium plays a critical role in regulating blood pressure and blood volume.