The Five W’s of Osmolality Testing

The time-honored formula for researching the fundamentals of a subject is “the Five W’s.” The Five W’s may initially call one’s mind back to grade-school but can actually be traced all the way back to Aristotle’s “Elements of Circumstance.”  

Those rudimental yet ever so interrogative words are, of course: Who, What, When, Where, Why?

Osmolality testing is on the rise, so it’s high time to elucidate the fundamentals using the tried-and-true Five W’s.

WHO: Laboratory scientists most often perform osmolality testing. These scientists may work at clinical laboratories that service doctors and the medical industry by specializing in the testing of bodily fluids such as blood, urine, plasma, and other biologics, or they may work at pharmaceutical labs in behalf of companies that produce liquid-based products such as functional beverages, personal lubricants, cosmetics or a wide spectrum of topicals. If a scientist is analyzing water-based solutions or solids intended for dissolution in water, chances are they are interested in osmolality.

WHAT: Osmolality is the concentration of all solutes in a given weight of water and is expressed as units of either osmolality (milliosmoles of solute per kilogram of water, mOsm/kg H2O) or osmolarity (milliosmoles of solute per liter of water, mOsm/L H2O). 


Simply stated, osmolality testing measures the density of dissolved particles in a solution. The higher the density measured, the higher the osmolality. 

WHEN: Doctors may send out specimens of blood, urine, plasma, etc. to clinical labs when they wish to ascertain the concentration of particles in bodily fluids. Biopharmaceutical or consumer product companies will often have the osmolality of their liquid-based products tested in the research stages of product development, or in conjunction with production as part of lot specification testing.     

WHERE: Laboratories equipped to test osmolality may be found within clinical institutions, medical/research organizations, universities, pharmaceutical companies, consumer product conglomerates, independent third-party laboratories or CRO’s (contract research organizations). There is often a clear distinction between the locations that test biohazards (i.e., bodily fluids) and those that test products intended for human consumption. The Osmolality Lab™, for example, does not accept hazardous biological or radioactive materials.   

WHY: Osmolality tests on bodily fluids can help doctors diagnose several possible conditions.

  • A blood osmolality test can help diagnose a fluid or electrolyte imbalance, including dehydration. 
  • A urine osmolality test can help tell us how well the kidneys are working. 
  • A serum osmolality test can analyze the density of sodium and electrolytes. 
  • A teardrop osmolality test can provide an objective diagnosis for dry eye.

Osmolality tests on liquid-based consumer products (such as beverages, cosmetics, personal lubricants, biopharmaceuticals, etc.) can help researchers, manufacturers, municipalities, consumer advocates and individuals to understand and optimize:

  • Hydration
  • Rehydration potential
  • Absorption
  • Purity
  • Stability
  • Characterization
  • Shelf-life
  • And more

Such variables are critical to overall product quality. Osmolality testing helps with in-process reagent quality and in reducing the risk of batch failures. There are products such as personal lubricants which are required to undergo osmolality testing before they can be approved by the FDA.

And there you have it, folks, the five W’s of osmolality testing!

I began this blog mentioning Aristotle, so please allow me to conclude with my all-time favorite Aristotle quote:

“We are what we repeatedly do. Excellence, then, is not an act, but a habit.”  

Philosophically speaking, osmolality testing is about excellence… excellence in medicine, excellence in R&D, excellence in quality control, scientifically substantiating facts around the people and the things we care for and have stewardship over through habitual reliance upon established methodologies.  

The Osmolality Lab™

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