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Log In Create Account. The principal investigators of the study request that you use the official version of the modified score here. The effect of hyperglycemia is well known for its lowering of serum sodium levels. The most commonly used correction factor is a 1.
Hillier and associates challenged this correction factor in a study that monitored serum sodium levels in a group of otherwise healthy persons who were rendered acutely insulin deficient. Healthy young volunteers were eligible for the study if they had no personal or family history of diabetes mellitus and were not taking any medications.
After an overnight fast, baseline serum glucose and sodium levels were measured. Subsequently, somatostatin was infused to suppress insulin secretion, along with a solution of 20 percent dextrose to increase the glucose concentration to more than mg per dL Once this glucose level was attained, the dextrose infusion was stopped and regular insulin was given a six-unit bolus and then six units an hour until the glucose concentration was less than mg per dL 7. Serum sodium and plasma glucose levels were measured three times in three subjects during induction of hyperglycemia.
These measurements were obtained in all subjects every 10 minutes once the glucose infusion was stopped and their glucose levels had returned to normal. A group of six volunteers, consisting of five men and one woman, completed the study. Serum sodium levels decreased in all volunteers as their glucose levels increased. This factor is significantly greater than the conventional correction factor. However, the decrease in serum sodium did not actually appear to be a linear value, particularly in volunteers whose glucose concentration was greater than mg per dL The 2.
The degree of hyponatremia was changed in Moreover, the median values for delta of sodium concentrations for each subgroup was 1. Comparison of the pairwise results for degree of hyponatremia between sodium concentrations before and after correction. Additionally, we have attempted to calculate corrected sodium concentrations in lipemic samples. Of 11 results, three The mean delta sodium concentration of 11 results was 1. When compared with the sodium concentrations on blood gas analysis five of 11 results , the mean difference was 1.
Hyponatremia is common in clinical practice. The causes of hyponatremia vary from mild disorder to systemic problem [ 14 ]. Typically, the main reason of hyponatremia is abnormal retention of water, such as excess intake or infusion of water, which leads to a hypotonic status [ 2 ]. In patients with mild symptoms, hyponatremia with signs and symptoms e. However, the approach to patients with hyponatremia should be performed with caution. Rapid or inappropriate correction of sodium concentration carries the risk of osmotic demyelination syndrome due to re-accumulation of osmolytes in the cells [ 5 ].
On the other hand, patients with pseudohyponatremia usually exhibit normal osmolar pressure, which, if mistaken for hypo-osmolar hyponatremia and given fluid restriction, is feared to further exacerbate the level of hyperviscosity and hypercoagulability [ 15 ].
As mentioned, serum sodium concentration is influenced by some factors. Hyperglycemia induces hyponatremia by an extracellular shift of water [ 8 ]; however, previous studies have shown that decrease in serum glucose concentration in patients with hyperglycemia results in increased serum sodium concentration due to return of water to the intercellular space [ 5 ], [ 9 ].
Thus, correction of serum sodium concentration by sodium glucose concentration correction is recommended in patients with hyperglycemia [ 4 ], [ 10 ]. Furthermore, hyperlipidemia and hyperproteinemia can also induce hyponatremia in samples measured using the I-ISE method.
The direct ISE method can overcome this problem and measure the actual sodium concentration, but the I-ISE method has been widely used in routine clinical laboratories. Because of relatively lower proportion of water fraction in samples that contain excess lipid or protein, an I-ISE-based analyzer has a tendency to report pseudohyponatremia.
Thus, actual serum water content should be calculated in hyperlipidemia or hyperproteinemia in order to avoid misclassification of hyponatremia. Certainly, there is a concern about the reliability and usefulness of the corrected sodium concentration. However, this change was implemented by our laboratory to help clinicians interpret their results with hyperglycemia or hyperlipidemia. We present both pre- and postcorrection concentrations and make them available for use in clinical settings. We retrospectively collected 1-year data on corrected sodium concentrations and evaluated the effects of the calculation on reduction of frequency of reports on pseudohyponatremia.
During the 1-year period, reports on pseudohyponatremia were reduced by After applying the formula, the degree of hyponatremia was unchanged only in The percentage of one grading difference was Furthermore, even in samples with severe hyperglycemia, three grading differences were observed in 14 samples. The trend of delta sodium concentrations was similar to that of other results in this study.
This study has some limitations. First, we used a correction factor of 1. However, Hiller [ 9 ] suggested a correction factor of 2. The hyponatremic effect of hyperglycemia has been analyzed in several studies, but the accuracy of each correction factor has not been proven yet. This is one of limitations of our study, and if a more reliable correction factor is proven, we will change the formula applied to our LIS.
Second, we did not assess clinical outcomes in this study. For these reasons, we could not reflect the clinical courses or outcomes. In this study, as we present both pre- and post-correction data, it is expected that clinicians will be able to use our data to make judgments if there is a discrepancy between the sodium level and actual clinical status of the patient with hyponatremia.
However, we did not include a survey of how clinicians feel and what points should be improved to our system. Therefore, further study is needed to reflect this clinical aspect. However, as mentioned, only 11 results had both hyponatremia and hyperlipidemia. Moreover, hyperproteinemia was not found in any samples.
Moreover, the number of samples was small, so statistically significant results were not obtained in hyperlipidemia. This is also one of limitations in our study. Further studies are required to evaluate the efficacy of the formula for hyperlipidemia on reduction of frequency of reports on pseudohyponatremia.
In conclusion, our laboratory has applied the formula of corrected sodium concentration for hyperglycemia or hyperlipidemia since August The report on corrected sodium concentration has reduced the frequency of pseudohyponatremia in hyperglycemic samples. Author contributions: All the authors have accepted responsibility for the entire content of this submitted manuscript and approved submission.
Competing interests: The funding organization s played no role in the study design; in the collection, analysis, and interpretation of data; in the writing of the report; or in the decision to submit the report for publication. Electrolyte disorders in community subjects: prevalence and risk factors. Am J Med ;— Search in Google Scholar. Oh MS, Briefel G. Evaluation of renal function, water, electrolytes, and acid-base balance.
Louis, MO: Elsevier Saunders, —
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