Gohel Mukesh, Makadia Jemil S, Chakrabarti Chandan
Department of Biochemistry, Smt NHL Municipal Medical College, Ahmedabad, Gujarat, India.
J Lab Physicians. 2021 Jun;13(2):144-147. doi: 10.1055/s-0041-1730821. Epub 2021 Jun 19.
The aim of this study was to see the effect of hypoproteinemia on electrolyte measurement by two different techniques, that is, direct ion selective electrode (ISE) and indirect ISE. It was an observational study in which 90 serum samples with normal protein content (Group-1) were subjected to sodium (Na ) and potassium (K ) measurements by direct and indirect ISE methods. In the same way, 90 serum samples with total protein < 5 g/dL (Group-2) were subjected to Na and K measurements by direct and indirect ISE methods. In samples from Group-1 patients, average Na was 138.1 ± 4.764 mmol/L by direct ISE method and 139.3 ± 3.887 mmol/L by indirect ISE method while average K was 4.41 ± 0.644 mmol/L by direct ISE method and 4.40 ± 0.592 mmol/L by indirect ISE method. There was no statistically significant difference in Na and K values measured by different methods. In samples from Group-2 patients, measured value of Na by direct ISE and indirect ISE was 134.57 ± 5.520 mmol/L and 138.64 ± 5.401 mmol/L, respectively. Difference between these two values was statistically significant with -value of < 0.0001, but direct ISE and indirect ISE measured values of K was 4.146 ± 0.9639 mmol/L and 4.186 ± 0.8989, respectively, with no significant difference. Direct and indirect ISE methods are not comparable and showing significantly different results for Na in case of hypoproteinemia. So, it is recommended that setups like intensive care unit or emergency department, where electrolyte values have significant treatment outcome, should follow direct ISE method and should compare its previous result with the same method. Both the methods should not be used interchangeably.
本研究的目的是观察低蛋白血症对两种不同技术（即直接离子选择性电极法（ISE）和间接ISE法）测定电解质的影响。
这是一项观察性研究，对90份蛋白质含量正常的血清样本（第1组）采用直接和间接ISE法进行钠（Na⁺）和钾（K⁺）测定。同样，对90份总蛋白<5g/dL的血清样本（第2组）采用直接和间接ISE法进行Na⁺和K⁺测定。
在第1组患者的样本中，直接ISE法测定的平均Na⁺为138.1±4.764mmol/L，间接ISE法测定的平均Na⁺为139.3±3.887mmol/L；直接ISE法测定的平均K⁺为4.41±0.644mmol/L，间接ISE法测定的平均K⁺为4.40±0.592mmol/L。不同方法测定的Na⁺和K⁺值无统计学显著差异。在第2组患者的样本中，直接ISE法和间接ISE法测定的Na⁺值分别为134.57±5.520mmol/L和138.64±5.401mmol/L。这两个值之间的差异具有统计学显著性，P值<0.0001，但直接ISE法和间接ISE法测定的K⁺值分别为4.146±0.9639mmol/L和4.186±0.8989，无显著差异。
直接和间接ISE法不可比，在低蛋白血症情况下，二者测定Na⁺的结果有显著差异。因此，建议在重症监护病房或急诊科等电解质值对治疗结果有重大影响的科室，应采用直接ISE法，并将其先前的结果与同一方法进行比较。两种方法不应交替使用。
