Hyperosmolarem

Hyperosmolarem, also referred to as a hyperosmolar state, is a term used to describe a condition in which the osmolality of body fluids is elevated above normal. Plasma osmolality in healthy adults typically ranges from about 275 to 295 mOsm/kg; values above this range indicate hyperosmolarem conditions. Elevated osmolality arises when water loss is excessive, or when solute load is increased relative to water.

Common causes include dehydration from vomiting, diarrhea, sweating, or inadequate fluid intake, as well as endocrine disorders such as diabetes mellitus with severe hyperglycemia or diabetic ketoacidosis; administration of hypertonic saline, mannitol, or substantial glucose loads can also raise osmolality. Less commonly, severe renal failure and marked lipid or urea changes may contribute.

Mechanistically, high osmolality draws water out of cells, producing cellular dehydration, especially in the brain. Clinically this can manifest as confusion, lethargy, seizures, or coma in severe cases. The onset can be gradual or rapid, and rapid correction carries risk of cerebral edema; therefore gradual management is emphasized.

Measurement may be direct or calculated using Osm = 2[Na+] + glucose/18 + BUN/2.8 (with glucose, BUN in mg/dL). Hyperosmolarem is commonly defined by plasma osmolality above 295 mOsm/kg, with severe hyperosmolarem states often exceeding 320 mOsm/kg. The condition is frequently seen in the context of hyperglycemic states or marked hypernatremia.

Treatment focuses on identifying the underlying cause and correcting fluid and electrolyte balance carefully to avoid rapid shifts. In diabetes-related hyperosmolarem states, initial management typically involves fluid resuscitation with isotonic saline, followed by correction of hyperglycemia and electrolytes while monitoring osmolality.