Plasma osmolalities were measured in 100 normal, 100 general hospital and 100 intensive care patients, and compared with the osmolalities calculated from the plasma concentrations of sodium, potassium, glucose and urea, using five different published formulae. The mean osmolar gaps in the 100 consecutive intensive care patients and the 100 general hospital patients were not significantly different from the mean osmolar gap in the 100 normal individuals. The formula which gave the least difference between the measured and calculated osmolality was 2 × Na + urea + glucose, where the concentrations of sodium, urea and glucose were measured in mmol/l.
EdelmanIS, LeibmanJ, O'MearaMP, BirkenfeldLW. Interrelations between serum sodium concentration, serum osmolarity and total exchangable potassium and total body water. J Clin Invest1958; 37:1236–1256.
2.
WeitzmanR, KleemanCR. Water metabolism and the neurohypophyseal hormones. In: MaxwellMH, KleemanCR, eds. Clinical disorders of fluid and electrolyte metabolism, 3rd ed. McGraw-Hill, New York1980; 531–645.
3.
RobinsonAG, LoebJN. Ethanol ingestion — commonest cause of elevated plasma osmolality?N Engl J Med1971; 284:1253–1255.
4.
DorwartVW, ChalmersL.Comparison of methods for calculating serum osmolality from chemical concentrations, and the prognostic value of such calculations. Clin Chem1975; 21:190–194.
5.
AlbrinkMJ, HaldPM, ManEB, PetersPJ. The displacement of serum water by the lipids of hyperlipidemic serum: A new method for rapid determination of serum water. J Clin Invest1955; 34:1483–1488.
6.
FrickPG, SchmidJR, KestlerJH. Hyponatremia associated with hyperprotinemia in multiple myelomaHelv Med Acta1966; 33:317–239.
7.
GlasserL, SternglanzPD, CombieJ, RobinsonA.Serum osmolality and its application to drug overdose. Am J Clin Pathol1973; 60:695–699.
8.
JacobsenD, BredesenJE, EideI, OstborgJ.Anion and osmolar gaps in the diagnosis of methanol and ethylene glycol poisoning. Acta Med Scand1982; 22:17–20.
9.
LundME, BannerW, FinleyPR, BurnhamL, DyeJA. Effects of alcohols and selected solvents on serum osmolality. J Toxicol Clin Toxicol1983; 20:115–132.
10.
BatumanV, MaesakaJK. Serum osmolality. N Engl J Med1984; 310–1609–1610.
11.
GennariFJ. Serum osmolality uses and limitations. N Engl J Med1984; 310:102–105.
12.
BoydDR, FolkFA, CondonRE, NeyhusLM, BakerRJ. Predictive value of serum osmolality in shock following major trauma. Surg Forum1970; 21:32–33.
13.
BoydDR, MansbergerARJr. Serum water and osmolal changes in hemorrhagic shock: an experimental and clinical study. Am Surg1968; 34:744–749.
14.
CoakleyJC, TobguiS, DennisPM. Screening for alcohol intoxication by the osmolar gap. Pathology1983; 15:321–323.
