Plasmaosmolaliteit

Plasmaosmolaliteit refers to the concentration of solutes in the plasma component of blood, expressed as the osmolality. Osmoality is a measure of the number of osmoles of solute per kilogram of solvent, providing an indication of the body's electrolyte and fluid balance. Plasma osmolality primarily depends on the levels of sodium, glucose, and urea, which are the major solutes influencing osmolar concentration.

Normal plasma osmolality ranges from approximately 275 to 295 milliosmoles per kilogram (mOsm/kg). It is a critical physiological parameter for maintaining cellular homeostasis, as it influences water movement between body compartments. The regulation of plasma osmolality is controlled by mechanisms involving the hypothalamus, antidiuretic hormone (ADH), and renal function. An increase in plasma osmolality usually triggers thirst and the release of ADH, leading to water retention and dilution of solutes. Conversely, decreased osmolality results in reduced ADH secretion and increased water excretion.

Abnormal plasma osmolality levels can indicate underlying health issues. Hyperosmolality (above 295 mOsm/kg) may be caused by dehydration, hyperglycemia, or increased urea levels, and can lead to cellular dehydration. Hypoosmolality (below 275 mOsm/kg) may result from overhydration, syndrome of inappropriate antidiuretic hormone secretion (SIADH), or kidney dysfunction, potentially causing cellular swelling.

Measurement of plasma osmolality is typically performed using an osmometer, which assesses the concentration of solutes in blood samples. The regulation of plasma osmolality is vital for physiological stability and is often evaluated clinically in cases of dehydration, electrolyte imbalance, or neurological disorders.