What is Osmolality?

Osmolality is a measure of the total number of particles (solutes) in a solution. Osmolality can also be affected by the amount of solvent in the system.

What is Osmometry?

Osmometry is the technique of using osmometers to measure solute to solvent ratios.

What is an Osmometer?

Osmometers can be used to measure the osmolality of a sample. The freezing point depression method is the most commonly used method in laboratories around the world. Because this technology is very sensitive and accurate, users find that it provides a rapid means of determining sample osmolality.

What is the Osmotic Gap?

The Osmotic Gap (or osmolal gap) is the difference between the actual, measured osmolality, and that calculated from the molal concentrations of all major solutes present in serum. This value indicates the presence of a small molecular weight compound(s) in serum. For practical purposes, the only substances that can produce an osmotic gap are alcohols, glycols, acetone, acetylsalicylic acid (aspirin) and paraldehyde. Presence of an osmotic gap is an indication that toxic ingestion has occurred.

What is Freezing Point Depression?

Freezing point depression is when the freezing point of a liquid (a solvent) is depressed when another compound is added, meaning that a solution has a lower freezing point than a pure solvent. Evaluating the freezing point depression of a sample can accurately measure the presence of all osmotically active substances in the sample.

How can Clinicians benefit from using Osmometers?

Clinicians can make more timely diagnoses and institute more appropriate patient care, which can translate to decreased health-care costs for medical institutions of any size, in any setting.

How can Osmometers help the Scientists and Researchers?

Pharmaceutical manufacturers and biotechnology researchers can benefit from routine osmolality testing. Benefits include monitoring drug development and media manufacture for proper consistency and formulation, and assuring proper shelf-life and product stability.

What are the main reasons for performing the following types of osmolality tests: Urine, Stool, and Serum

Urine osmolality provides the best estimate of the kidney’s concentrating ability, calculating osmotic gap, free water clearance, and an athlete’s hydration status, to name a few. Measurement of osmolality in stool is helpful when evaluating patients with diarrhea.

Serum osmolality is a critical clinical tool for supporting many diagnoses such as rapid screening for alcohol intoxication and certain toxins, differential diagnosis of hyponatremia and hypernatremia, establishing criteria for hemodialysis, proper urology/renal function, emergency medicine, non-ketoic diabetic coma, and many others.