Osmolality is a valuable and cost-effective measurement tool which is used in a wide range of clinical, biotechnology, pharmaceutical, industrial, food testing, athletic, and forensic applications. Freezing point determination has virtually limitless applications where there is a need to determine concentrations of solutes in a solutions. We have attempted to provide you with example applications illustrative of the variety and range of the uses for osmolality.
Osmolality, as determined by freezing-point depression, is the preferred method for clinical applications. Other methods are insensitive to volatile solutes, and can give misleading results in toxicology and evaluation of diabetic complications. Today’s freezing-point osmometers offer tighter performance CVs, leading the College of American Pathologists to recognize a distinct category of results in performance surveys. Advanced® Osmometers set the gold standard for accuracy, performance, and reliability in the clinical lab setting and are used in thousands of clinical and hospital laboratories worldwide.
The speed and simplicity of testing with a modern Advanced Instruments osmometer makes it a very useful first step in the evaluation of cases presented in the emergency room to monitor the response to fluid therapy and recovery from surgical procedures. Freezing point is the method of choice for osmometers in this field because they are sensitive to all types of solutes. Vapor pressure osmometers will not read volatile solutes, which may deprive the clinician of significant information in cases of toxic ingestion of methanol or ethylene glycol, as well as the necessary ability to monitor therapeutic infusions of mannitol.
- Alcohol Intoxication: The ingestion of toxic substances, often as a cheap alternative to ethanol, is a frequent occurrence and not limited to inner city hospitals. Ethanol ingestion will elevate serum osmolality by 23 mOsm for each 100mg/dl (0.1 %.) Measured ethanol in combination with measured osmolality can confirm whether or not intoxication is due to ethanol. Differentiation from alcohols, by enzymatic means, must be confirmed, but in all instances the course of treatment is most easily monitored by routine osmolality.
- Head Injury/Shock: When normal CNS and renal homeostatic mechanisms are unresponsive, serum and urine osmolality can provide rapid determination of appropriate IV Therapy. In the use of mannitol for treatment of brain swelling, osmolality guides appropriate usage of the drug.
- Coma: In cases where patients are non-responsive or demonstrate erratic behavior, serum osmolality is a valuable tool to assess mental status state, patient state of hydration and osmolality.
- Diabetic Coma: Advanced Osmometers yield accurate results in the presence or absence of volatiles. Hence, the serum osmolality in ketoic and non-ketoic patients can be measured with confidence.
- Burns: Osmolality offers a rapid assessment of a burn patient’s state of hydration and helps to monitor proper fluid therapy.
- Drug Intoxication Screening: Probing the osmolal gap, one might find a variety of small MW solutes, at toxic levels, which are most easily detected by an osmometer. Methanol, ethylene glycol, and acetylsalicylic acid (aspirin) are the usual suspects in an emergency room setting.
Infant Nutritional Products
Understanding and monitoring the osmolality of human milk, milk fortifiers, pediatric medications and infant nutritional products is a very relevant topic in the neonatal intensive care setting. Administration of hyperosmolar feeds in neonates has been linked to a wide variety of adverse conditions: altered nutrient absorption, hypertonic dehydration, diarrhea, intestinal ischemia, as well as more severe gastrointestinal abnormalities including necrotizing enterocolitis (NEC).
Common feeding and supplementation practices in the NICU do little to confirm the actual osmolality of individual feed samples, and in many cases can impact patient safety by increasing the risk of hyperosmolar feedings.
Many neonatal intensive care units have adopted the use of osmometry as a quality control tool to avoid incidences of hyperosmolar feedings and improve patient safety.
Milk as a Vehicle for Oral Medications: Hidden Osmoles
PG Radmacher, M D Adamkin, S T Lewis and D H Adamkin
Internal Medicine and Endocrinology
Endocrinologists and Internal Medicine specialists frequently rely on Advanced Instruments’ Osmometer osmolality data as a valuable tool to better understand the relationships between hormones and their effects on serum and urine osmolality. Osmolality data is relied upon to make more informed diagnoses and the subsequent treatment protocols for these types of conditions.
- Hyper/Hyponatremia: Osmolality differentiates between real and factitious hyponatremia. Urine osmolality helps identify the genesis of hypo- and hyper-natremia.
- Inappropriate ADH Syndrome: Serum and urine osmolality help determine whether SIADH is present in a patient with normal blood volume.
- ADH Therapy: Urine osmolality provides a rapid measure of patient response, assisting therapy modification.
- Diabetes Insipidus: Urine osmolality can measure the effects of humoral factors and offers rapid determination of the disease’s etiology.
- Insulin Therapy: Osmolality provides rapid assessment of the effectiveness of the insulin therapy.
- Differential Diagnosis of Polyuria: Osmolality can help to differentiate between diabetes insipidus and psychogenic polyuria.
Obstetrics and Gynecology
Advanced Instruments’ osmometer for osmolality testing is a powerful tool in Obstetrics and Gynecology since monitoring fluid balance is critical during the late-term stages of pregnancy. Numerous research articles and publications leveraging osmolality testing have been published in this field.
- Pre-Eclampic Patients: Osmolality helps to assess renal function, fluid balance and electrolyte balance and to determine the effects of magnesium sulfate therapy in pre-eclampic women.
- Fluid and Electrolyte Balance in Complicated Pregnancies: Cryoscopic osmolality determination is a reliable, rapid and inexpensive way to assess renal function as well as fluid and electrolyte balance during complicated pregnancies.
- IVF/ ICSI: Osmolality is an important tool to insure the morphology of gametes and embryos; it is particularly important during several days of incubation.
Pharmaceutical and Biotechnology
Pharmaceutical and biotechnology companies can use Advanced Instruments osmometers for osmolality testing extensively in their R&D, production, quality and process control operations to ensure product safety and the efficiency of their production capabilities. Freezing point technology has proven to be the industry-preferred method due to its accuracy, performance and reliability.
- Compliance: Advanced Instruments osmometers comply with the latest United States Pharmacopeia (USP) National Formulary Chapter 785, Osmolality and Osmolarity and European Pharmacopeia (EP) Osmolality Chapter 2.2.35.
- Improved Cell Culture Yield: Cell culture has become one of the major tools used in the life sciences today used in a variety of applications including cancer research, toxicity testing, virology, drug screening & development, and large-scale cell-based production of biologicals. Enabling cultured tissue cells to retain their original morphology and function requires reproducing the tissue’s natural in vivo environment. A key consideration in this effort is the osmolality of the culture medium. When cells for culture are removed from bodily tissue, they are placed in a foreign environment and are bathed by a liquid medium, an environment where the osmolality of the culture medium, if not made iso-osmotic, can cause osmotic shock. Osmotic shock causes cell volume changes. Studies have shown that even minor short-term modulation of cell volume can change cellular metabolism and gene expression. It makes sense, then, to be aware of the influence of the osmolality of the medium being used for tissue culture. It makes sense to test for osmotic pressure, for tonicity, and to be aware that, in some cases, providing an iso-osmotic medium is crucial.
- Cell Culture Process Development/Optimization: Finding the optimal mixture of culture media for a particular cell-line can be a daunting process. Since typical media powder can have 60-100 components, an exponential amount of experimental permutations are required to find the optimal “happy” media environment. Osmolality is a critical component to this testing since osmotic pressure regulates the flow of substances (media) in and out of the cell.
- Media Preparation and Quality Control: Experience has proved that conscientious osmolality testing leads to higher yields and more significant observations. Because lot-to-lot variations can occur whether culture media is reconstituted or purchased, all media for the culture of both plant and animal tissue should be tested before use. Since density gradients for cell separation “want” to be iso-osmotic, significantly enhanced yields have been reported with careful osmolality monitoring. Further, maintaining the proper osmotic concentrations of fixing solutions can increase resolution and clarity in cell microscopy
- Pharmaceutical Formulation Development: Salts or non-electrolytes (e.g. glycerin) are often added to protein formulations to achieve an isotonic solution. Non-electrolytes are often preferred to salts as tonicity adjustors because of potential issues salts cause with protein precipitation. Intrathecal and epidural injection drugs require very precise specifications for the product to be isotonic. Osmolality testing provides these stringent assurances
- General Quality Control: Osmolality is a rapid and accurate QC measurement for a number of pharmaceutical and biopharmaceutical applications, including: finished product testing, infant formulas, ophthalmic solutions, electrolyte solutions, tissue cultures, culture media, IV solutions and other parenterals.
- Bioprocess Monitoring of Therapeutic Proteins: Osmolality is a key measurement utilized to monitor the progress of fermentation within bioreactors to ensure that the process is moving forward according to plan and that contamination has not occurred.
Surgery and Critical Care
The speed and simplicity of testing with an Advanced Instrument freezing point osmometer makes it a critical first step in the evaluation of cases presented to the emergency room, in monitoring response to IV therapy, and in monitoring the recovery from surgical procedures.
- Hypovolemic/Hypervolemic Shock Prevention: Osmolality can be used to monitor perfusate during coronary bypass or renal surgery to avoid hypovolemic shock.
- Electrolyte/Metabolite Imbalance: Osmolality offers rapid detection of post-surgery electrolyte/metabolite imbalance. In urologic surgery, the difference between calculated and measured osmolality can be used to estimate absorption of irrigation fluid.
- IV Therapy: Osmolality can help monitor and manage IV therapy.
- Liver Transplant: Large increases in osmolality can occur due to blood loss or transfusion, changes in plasma sodium levels, or the administration of sodium bicarbonate.
- Glycine Uptake: Surgical procedures of long duration can cause the uptake of irrigation fluid that will contribute to an elevated osmolality.
- Blood Bank: Osmolality is measured to ensure that glycerol has been completely removed from the frozen blood cells.
Urology and Renal
An Advanced Instruments osmometer is an indispensable aid to understanding proper renal function, the differing responses of serum and urine to water load and deprivation, and to making an appropriate diagnosis. The provision of a calculated osmolality, by an automated electrolyte analyzer, does not absolve the pathologist of the need to measure osmolality directly. To the contrary, much useful information can be gained by an investigation of the osmotic gap.
- Differential Diagnosis of Renal Malfunction: Urine and serum osmolality respond differently to water overload, water deprivation, diuretics, anti-diuretic hormone (ADH) and insulin.
- Uremia: The accumulation of unmeasured metabolites in the blood can be an early indication of uremia. The difference between measured and calculated osmolality can determine the accumulation of unmeasured metabolites in the blood. Once baseline electrolyte levels are established, osmolality can be used to monitor the progress of the uremic patient.
- Osmotic Gap and Free Water Clearance: Clearance can be calculated immediately from urine and serum osmolality, providing the earliest marker of tubular damage.
- Renal Dialysis: In patients with known renal disease, elevated serum osmolality can indicate the need for dialysis. During therapy with diuretics, dialystate osmolality can be used to monitor progress.