plasmanosmolaritet

Plasmanosmolaritet, often referred to as plasma osmolality, is a measure of the concentration of dissolved particles in the blood plasma. It reflects the total solute concentration per unit volume of plasma. This concentration is primarily determined by the levels of electrolytes such as sodium, chloride, and bicarbonate, as well as non-electrolyte solutes like glucose and urea.

The body tightly regulates plasma osmolality to maintain cellular integrity and function. Deviations from the normal range can have significant physiological consequences. For instance, a high plasma osmolality indicates that the plasma is more concentrated, which can occur due to dehydration or an excess of solutes. This can draw water out of cells, causing them to shrink. Conversely, a low plasma osmolality means the plasma is less concentrated, potentially leading to cells swelling as water moves into them.

Hormones like antidiuretic hormone (ADH) play a crucial role in managing plasma osmolality. When osmolality rises, ADH is released, prompting the kidneys to reabsorb more water and reduce urine output, thereby diluting the plasma. When osmolality falls, ADH release is suppressed, leading to increased water excretion.

Measuring plasma osmolality is a common diagnostic tool in clinical medicine. It helps evaluate fluid and electrolyte balance, diagnose conditions like diabetes insipidus or syndrome of inappropriate antidiuretic hormone (SIADH), and monitor the effectiveness of treatments for various medical issues. The typical normal range for plasma osmolality in adults is approximately 275 to 295 milliosmoles per kilogram of plasma water (mOsm/kg H2O).