Jump to ContentJump to Main Navigation
Show Summary Details
More options …

Clinical Chemistry and Laboratory Medicine (CCLM)

Published in Association with the European Federation of Clinical Chemistry and Laboratory Medicine (EFLM)

Editor-in-Chief: Plebani, Mario

Ed. by Gillery, Philippe / Lackner, Karl J. / Lippi, Giuseppe / Melichar, Bohuslav / Payne, Deborah A. / Schlattmann, Peter / Tate, Jillian R.

12 Issues per year


IMPACT FACTOR 2016: 3.432

CiteScore 2016: 2.21

SCImago Journal Rank (SJR) 2016: 1.000
Source Normalized Impact per Paper (SNIP) 2016: 1.112

Online
ISSN
1437-4331
See all formats and pricing
More options …
Volume 43, Issue 6 (Jun 2005)

Issues

Comparison of methods for calculating serum osmolality: multivariate linear regression analysis

Mehdi Rasouli
  • Department of Clinical Biochemistry, Faculty of Medicine, Medical Sciences University of Mazandaran, Sari, Iran
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
/ Kiarash Rezaei Kalantari
  • Department of Clinical Biochemistry, Faculty of Medicine, Medical Sciences University of Mazandaran, Sari, Iran
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
Published Online: 2014-06-11 | DOI: https://doi.org/10.1515/CCLM.2005.109

Abstract

Background: There are several methods for calculating serum osmolality, and their accordance with measured osmolality is the subject of controversy.

Methods: The concentrations of sodium, potassium, glucose, blood urea nitrogen (BUN) and osmolalities of 210 serum samples were measured. Two empirical equations were deduced for the calculation of serum osmolality by regression analysis of the data. To choose the best equation, chemical concentrations were also used to calculate osmolalities according to our formulas and 16 different equations were taken from the literature and compared with the measured osmolalities. Correlation and linear regression analyses were performed using Excel and SPSS software.

Results: Multiple linear regression analysis showed that serum concentrations of sodium (β=0.778, p≤0.000), BUN (β=0.315, p≤0.000), glucose (β=0.0.089, p≤0.007) and potassium (β=0.109, p≤0.008) are strong predictors of serum osmolality. The data were also analyzed by manual linear regression to yield the equations: osmolality=1.897[Na +]+glucose+BUN+13.5, and osmolality=1.90[Na ++K +]+glucose+BUN+5.0. The osmotic coefficient for sodium and potassium solutes was deduced to be 0.949 from the slope of the curves of measured osmolality vs. [Na +] and [Na ++K +], respectively. The inclusion of a BUN value in the equation for osmolality increased the correlation coefficient by approximately 450% and decreased the SD of difference by approximately 35% (p≤0.002). Inclusion of the osmotic coefficient for sodium solutes caused an underestimation of measured osmolality and positive osmolal gap unless an appropriate coefficient, constant value and/or the potassium value were included in the equation. The agreement was not improved when molal chemical concentrations were used instead of molar values. The formula presented by Dorwart and Chalmers gave inferior results to those obtained with our formulas.

Conclusions: Our data suggest use of the Worthley et al. formula Osm=2[Na +]+glucose+BUN for rapid mental calculation and the formulas of Bhagat et al. or ours for calculation of serum osmolality by equipment linked to a computer.

Keywords: osmolal gap; osmolality; osmotic coefficient; regression analysis; sodium.

References

  • 1

    Kill F. Molecular mechanisms of osmosis. Am J Physiol 1989; 25: R801–8. Google Scholar

  • 2

    Wrenn KD. Osmolality. Ann Intern Med 1991; 114: 337–8. CrossrefGoogle Scholar

  • 3

    Kaplan LA. Osmolality. In: Pesce AJ, Kaplan LA, editors. Methods in clinical chemistry. St. Louis, MO: CV Mosby, 1987:18–22. Google Scholar

  • 4

    Gennari FJ. Serum osmolality, uses and limitations. N Engl J Med 1984; 310: 102–5. CrossrefGoogle Scholar

  • 5

    Dorwart WV, Chalmers L. Comparison of methods for calculating serum osmolality from chemical concentrations, and prognostic value of such calculation. Clin Chem 1975; 21: 190–4. Google Scholar

  • 6

    Coakley JC, Tobgui S, Dennis PM. Screening for alcohol intoxication by the osmolar gap. Pathology 1983; 15: 321–3. CrossrefGoogle Scholar

  • 7

    Sklar AH, Linas SL. The osmolal gap in renal failure. Ann Intern Med 1983; 98: 481–2. CrossrefGoogle Scholar

  • 8

    Bhagat CI, Garcia-Webb P, Fletcher E, Beilby JP. Calculated vs. measured plasma osmolality revisited. Clin Chem 1984; 30: 1703–5. Google Scholar

  • 9

    Scott MG, Heusel JW, LeGrys VA, Siggaard-Andersen O. Electrolytes and blood gases. In: Burtis CA, Ashwood ER, editors. Tietz textbook of clinical biochemistry. Philadelphia, PA: WB Saunders, 1986:1172–253. Google Scholar

  • 10

    Bohnen N, Terwel D, Markernik M, Ten Haaf JA, Jolles J. Pitfalls in the measurement of plasma osmolality pertinent to research in vasopressin and water metabolism. Clin Chem 1992; 38: 2278–80. Google Scholar

  • 11

    Seifarth CC, Miertschischk J, Hahn EG, Hensen J. Measurement of serum and plasma osmolality in healthy young humans: influence of time and storage conditions. Clin Chem Lab Med 2004; 42: 927–32. CrossrefGoogle Scholar

  • 12

    Winters RW. Disorders of electrolyte and acid-base metabolism. In: Barnett L, editor. Pediatrics. New York: Appleton Century Crofts, 1968:336–8. Google Scholar

  • 13

    Hoffman WS, editor. The biochemistry of clinical medicine. Chicago, IL: Yearbook Publishers, 1970:228. Google Scholar

  • 14

    Jetter WW. Clinical osmometry. Pa Med 1969; 75: 72–9. Google Scholar

  • 15

    Edelman IS, Leibman J, O'Meara MP, Birkenfeld LW. Interrelations between sodium concentration, serum osmolarity and total exchangeable potassium and total body water. J Clin Invest 1958; 37: 1236–56. CrossrefGoogle Scholar

  • 16

    Stevenson RE, Bowyer FP. Hyperglycemia with hyperosmolal dehydration in nondiabetic infants. J Pediatr 1970; 77: 818–23. CrossrefGoogle Scholar

  • 17

    Weisberg HF. Osmolality. American Society of Clinical Pathologists, Commission on Continuing Education, vol. 71. Chicago, IL: ASCP Press, 1971:1–49. Google Scholar

  • 18

    Purssell RA, Pudek M, Brubacher J, Abu-Laban RB. Derivation and validation of a formula to calculate the contribution of ethanol to the osmolal gap. Ann Emerg Med 2001; 38: 653–9. CrossrefGoogle Scholar

  • 19

    Worthley LI, Guerin M, Pain RW. For calculating osmolality, the simplest formula is the best. Anesth Intensive Care 1987; 15: 199–202. Google Scholar

  • 20

    Gerich JE, Martin MM, Recant L. Clinical and metabolic characteristics of hyperosmolar non-ketotic coma. Diabetes 1971; 20: 228–35. CrossrefGoogle Scholar

  • 21

    Tormey WP. Are the increasing clinical demands for osmolality measurements and their associated electrolytes appropriate? Ir J Med Sci 1997; 166: 75–9. CrossrefGoogle Scholar

  • 22

    Glasser L, Sternglanz PD, Comble J, Robinson A. Serum osmolality and its applicability to drug overdose. Am J Clin Pathol 1973; 60: 695–9. CrossrefGoogle Scholar

  • 23

    Boyd DR, Baker RJ. Osmometry: a new beside laboratory aid for the management of surgical patients. Surg Clin North Am 1971; 51: 241–50. CrossrefGoogle Scholar

  • 24

    Weisberg HF. Osmolality: calculated, delta and more formula. Clin Chem 1975; 21: 1182–5. Google Scholar

  • 25

    Garcia-Morales EJ, Cariappa R, Parvin CA, Scott M, Diringer MN. Osmole gap in neurologic-neurosurgical intensive care unit. Its normal value, calculation and relationship with mannitol serum concentrations. Crit Care Med 2004; 32: 986–91. CrossrefGoogle Scholar

  • 26

    Partanen JI, Minkkinen PO. Thermodynamic activity quantities in aqueous sodium and potassium chloride solutions at 298.15 K up to a molality of 2.0mol/kg −1. Acta Chem Scand 1993; 47: 768–76. Google Scholar

  • 27

    Noggle JH, editor. Physical chemistry. Boston, MA: Little Brow, 1985:363–417. Google Scholar

  • 28

    Langhoff E, Ladefoged J. Sodium activity, sodium concentration and osmolality in plasma in acute and chronic renal failure. Clin Chem 1985; 31: 1811–4. Google Scholar

About the article

Corresponding author: Mehdi Rasouli, Associate Professor, Department of Clinical Biochemistry, Faculty of Medicine, Medical Sciences University of Mazandaran, Sari, Iran Phone: +98-912-3489560, Fax: +98-151-3247106,


Received: 2005-01-05

Accepted: 2005-04-12

Published Online: 2014-06-11

Published in Print: 2005-06-01


Citation Information: Clinical Chemistry and Laboratory Medicine (CCLM), ISSN (Online) 1437-4331, ISSN (Print) 1434-6621, DOI: https://doi.org/10.1515/CCLM.2005.109.

Export Citation

© Walter de Gruyter Berlin New York. Copyright Clearance Center

Citing Articles

Here you can find all Crossref-listed publications in which this article is cited. If you would like to receive automatic email messages as soon as this article is cited in other publications, simply activate the “Citation Alert” on the top of this page.

[1]
Fanny Lepeytre, Marc Ghannoum, Hélène Ammann, François Madore, Stéphan Troyanov, Rémi Goupil, and Josée Bouchard
American Journal of Kidney Diseases, 2017, Volume 70, Number 3, Page 347
[2]
Urs Wilgen, Carel J Pretorius, and Jacobus PJ Ungerer
Annals of Clinical Biochemistry, 2017, Page 000456321769405
[3]
Macià Sureda-Vives, Daniel Morell-Garcia, Ana Rubio-Alaejos, Laura Valiña, Juan Robles, and Josep Miquel Bauça
Clinical Biochemistry, 2017, Volume 50, Number 13-14, Page 772
[4]
David J McQuade, Paul I Dargan, and David M Wood
Annals of Clinical Biochemistry, 2014, Volume 51, Number 2, Page 167
[5]
Natalie H. Hall, Ramiro Isaza, James S. Hall, Ellen Wiedner, Bettina L. Conrad, and Heather L. Wamsley
Journal of Veterinary Diagnostic Investigation, 2012, Volume 24, Number 4, Page 688
[6]
Seunghun Ock, Sion Jo, Jae Baek Lee, Youngho Jin, Taeoh Jeong, Jaechol Yoon, and Boyoung Park
The American Journal of Emergency Medicine, 2016, Volume 34, Number 12, Page 2343
[7]
Mehdi Rasouli
Clinical Biochemistry, 2016, Volume 49, Number 12, Page 936
[8]
Nikolay V. Voskoboev, Sarah J. Cambern, Matthew M. Hanley, Callen D. Giesen, Jason J. Schilling, Paul J. Jannetto, John C. Lieske, and Darci R. Block
Clinical Biochemistry, 2015, Volume 48, Number 16-17, Page 1126
[9]
José L. Martín-Calderón, Fernando Bustos, Lyliam R. Tuesta-Reina, Julia M. Varona, Luis Caballero, and Fernando Solano
Clinical Biochemistry, 2015, Volume 48, Number 7-8, Page 529
[10]
Nancy A. Stotts, Shoshana R. Arai, Bruce A. Cooper, Judith E. Nelson, and Kathleen A. Puntillo
Journal of Pain and Symptom Management, 2015, Volume 49, Number 3, Page 530
[11]
Daniel T. Dugger, Steven E. Epstein, Kate Hopper, and Matthew S. Mellema
Journal of Veterinary Emergency and Critical Care, 2014, Volume 24, Number 2, Page 188
[12]
Samuel N. Cheuvront, Robert W. Kenefick, Kristen R. Heavens, and Marissa G. Spitz
Journal of Clinical Laboratory Analysis, 2014, Volume 28, Number 5, Page 368
[13]
Jelena Maletkovic and Andrew Drexler
Endocrinology and Metabolism Clinics of North America, 2013, Volume 42, Number 4, Page 677
[14]
D. T. Dugger, M. S. Mellema, K. Hopper, and S. E. Epstein
Journal of Small Animal Practice, 2013, Volume 54, Number 4, Page 184
[15]
Frank Donnerstag, Xiaoqi Ding, Lars Pape, Eva Bültmann, Thomas Lücke, Jan Zajaczek, Ludwig Hoy, Anibh Martin Das, Heinrich Lanfermann, Jochen Ehrich, and Hans Hartmann
European Radiology, 2012, Volume 22, Number 3, Page 506
[16]
Tetsu Akimoto, Chiharu Ito, Maki Kato, Manabu Ogura, Shigeaki Muto, and Eiji Kusano
Medical Hypotheses, 2011, Volume 77, Number 4, Page 601
[17]
Gustavo J. Rodriguez, Steve M. Cordina, Gabriela Vazquez, M. Fareed K. Suri, Jawad F. Kirmani, Mustapha A. Ezzeddine, and Adnan I. Qureshi
Neurocritical Care, 2009, Volume 10, Number 2, Page 187
[18]
Mehdi Rasouli, Asadollah Mohseni Kiasari, and Shahin Arab
Clinical and Experimental Pharmacology and Physiology, 2008, Volume 35, Number 8, Page 889
[19]
Thomas Schermerhorn and Stephen C. Barr
Journal of Veterinary Emergency and Critical Care, 2007, Volume 17, Number 1, Page 3

Comments (0)

Please log in or register to comment.
Log in