osmolality


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osmolality

 [oz″mo-lal´ĭ-te]
the concentration of a solution in terms of osmoles of solutes per kilogram of solvent.
serum osmolality a measure of the number of dissolved particles per unit of water in serum. In a solution, the fewer the particles of solute in proportion to the number of units of water (solvent), the less concentrated the solution. A low serum osmolality means a higher than usual amount of water in relation to the amount of particles dissolved in it, and accompanies overhydration, or edema. An increased serum osmolality indicates deficient fluid volume. Measurement of the serum osmolality gives information about the hydration status within the cells because of the osmotic equilibrium that is constantly being maintained on either side of the cell membrane (homeostasis). Water moves freely back and forth across the membrane in response to the osmolar pressure being exerted by the molecules of solute in the intracellular and extracellular fluids. Serum osmolality reflects the status of hydration of the intracellular as well as the extracellular compartments and thus describes total body hydration. The normal value for serum osmolality is 270–300 mOsm/kg water.
urine osmolality a measure of the number of dissolved particles per unit of water in the urine. A more accurate measure of urine concentration than specific gravity, urine osmolality is useful in diagnosing renal disorders of urinary concentration and dilution and in assessing status of hydration. The normal value is 500 to 800 mOsm/L.

os·mo·lal·i·ty

(oz'mō-lal'i-tē), Do not confuse this word with osmolarity.
The concentration of a solution expressed in osmoles of solute particles per kilogram of soluent.

osmolality

/os·mo·lal·i·ty/ (oz″mo-lal´it-e) the concentration of a solution in terms of osmoles of solute per kilogram of solvent.

osmolality

[oz′mōlal′itē]
the osmotic pressure of a solution expressed in osmols or milliosmols per kilogram of water. Normal adult blood osmolality is 285 to 295 mOsm/kg H2O. Compare osmolarity.

osmolality

Toxicology A measure of the amount of osmotically effective solute/1000 g of solvent; serum osmolality is↑ in Ethanol, azotemia, dehydration, DM, hypercalcemia, hyperglycemia, hypernatremia, ethylene glycol, glycerine, INH, ketosis, mannitol therapy, methanol, pyelonephritis, renal tubular necrosis, diabetes insipidus, shock, sorbitol, uremia ↓ in Overhydation, ↑ fluid intake, ↓ Na+, paraneoplastic syndrome, SIADH; urine osmolality is ↑ in SIADH, liver disease, heart disease, dehydration ↓ in Overhydration, diabetes insipidus, ↓ K+ Ref range Serum, 275-295 mOsm/Kg; urine 50–1400 mOsm/Kg Critical (panic) values ≤ 265 mOsm/Kg; ≥ 320 mOsm/Kg. See Delta osmolality, Effective osmolality.

os·mo·lal·i·ty

(oz'mō-lal'i-tē)
The concentration of a solution expressed in osmoles of solute particles per kilogram of solvent.

osmolality

The property of a solution that depends on its concentration in osmolal units. See OSMOLE.

Osmolality

A measurement of urine concentration that depends on the number of particles dissolved in it. Values are expressed as milliosmols per kilogram (mOsm/kg) of water.

osmolality

the concentration of osmotically active particles in a solution, expressed as the number of osmoles per kilogram (Osm.kg-) of solution. In blood plasma, osmolality (280 - 300 mOsm.kg-1) is very slightly less than osmolarity (in mOsm.L-1) because the presence of large molecules (e.g. lipids) adds to the volume that contains 1 kg of water (plasma is about 94% water). The two terms are often incorrectly used interchangeably; osmolality applies appropriately to body fluids. Measurement allows assessment of dehydration/overhydration.

osmolality

the concentration of a solution in terms of osmoles of solutes per kilogram of solvent.

serum osmolality
a measure of the number of dissolved particles per unit of water in serum. In a solution, the fewer the particles of solute in proportion to the number of units of water (solvent), the less concentrated the solution. A low serum osmolality would be indicative of a higher than usual amount of water in relation to the amount of particles dissolved in it. It would be expected, then, that a low serum osmolality would accompany overhydration, or edema, and an increased serum osmolality would be present in a state of fluid volume deficit.
Measurement of the serum osmolality gives information about the hydration status within the cells because of the osmotic equilibrium that is constantly being maintained on either side of the cell membrane (homeostasis).
Water moves freely back and forth across the membrane in response to the osmotic pressure being exerted by the molecules of solute in the intracellular and extracellular fluids. Serum osmolality reflects the status of hydration of the intracellular as well as the extracellular compartments and thus describes total body hydration.
urine osmolality
a measure of the number of dissolved particles per unit of water in the urine. A more accurate measure of urine concentration than specific gravity, urine osmolality is useful in diagnosing renal disorders of urinary concentration and dilution and in assessing status of hydration.
References in periodicals archive ?
The EDTA acts as a stabilizer of these collagen fibrils, while the mannitol provides physiologic osmolality.
Essentially a "smart" mouth guard, this revolutionary product will measure osmolality in the bio fluid by utilizing high sensitivity sensors.
Plasma glutamine, glucose, electrolytes and osmolality were measured prior to each run, and at 30, 45 and 60 minutes.
0 Bilirubin [micro]mol/L -- -- mg/dL -- -- Chloride mmol/L 75 (8) 60-90 Osmolality mmol/kg 250 (13) 230-280 Urea nitrogen mmol/L -- -- mg/dL -- -- Uric acid [micro]mol/L -- -- mg/dL -- -- CSF glucose mmol/L 2.
The lower osmolality and increased solubility in water lowers LOCM toxicity.
Increased hemoglobin during acute stroke seems related to clinical deterioration after stroke, as does an elevated blood urea nitrogen (BUN)/creatinine ratio and serum osmolality.
Storage containers were sealed securely to avoid any moisture contamination that tends to alter the pH or osmolality of the media.
Severe Hyponatremia with High Urine Sodium and Osmolality (28 827) Authors: Joost van der Hoek, Ewout J.
Abstract: To evaluate the relationship between osmolality and specific gravity of urine samples from clinically normal adult parrots and to determine a formula to convert urine specific gravity (USG) measured on a reference scale to a more accurate USG value for an avian species, urine samples were collected opportunistically from a colony of Hispaniolan Amazon parrots (Amazona ventralis).