Külpmann W R
Institut für Klinische Chemie I, Medizinische Hochschule Hannover, Bundesrepublik Deutschland.
Wien Klin Wochenschr Suppl. 1992;192:37-41.
In clinical chemistry two different quantities are determined for electrolytes: 1) Electrolyte concentration (total) in serum (S) e.g. S-sodium (mmol/l), S-calcium (mmol/l). 2) Electrolyte concentration (ionized) in serum water [S(W)] e.g. S(W)-sodium, ionized (mmol/kg), S(W)-calcium, ionized (mmol/kg) ad 1) For the determination of the electrolyte concentration in serum, various methods are used: Sodium, potassium: Flame atomic emission spectrometry, ion-selective electrodes after dilution of the sample, enzymatic methods; Chloride: Coulometry, absorption spectrometry after chemical reaction, enzymatic method; Calcium, magnesium: Flame atomic absorption spectrometry, flame atomic emission spectrometry (calcium), absorption spectrometry after chemical reaction, enzymatic method (magnesium). A safe and unambiguous medical interpretation of sodium and chloride ion concentration in serum is not possible without knowledge of the water concentration or of the lipid and protein concentration of the individual sample. The same holds true--even though for some other reasons--for calcium concentration in whole serum. The reference intervals of the pertinent ions are valid only for samples, which are "normal" with respect to the size of the electrolyte-free compartment and--depending on the method--the amount of complex-binding ions. ad 2) For the determination of the concentration of the "ionized" or "free" fraction of sodium, potassium, calcium, and magnesium in serum water (or the extracellular water phase of whole blood) the following method is only applicable: Ion selective electrode without dilution of the sample. A save medical interpretation of the ionized electrolyte concentration in serum water is possible without knowledge of the water concentration of the individual sample, because these quantities are independent from the size of the electrolyte-free compartment.(ABSTRACT TRUNCATED AT 250 WORDS)
在临床化学中，电解质可测定两种不同的量：1）血清（S）中电解质的浓度（总量），例如血清钠（mmol/L）、血清钙（mmol/L）。2）血清水[S（W）]中电解质的浓度（离子化），例如离子化血清钠（mmol/kg）、离子化血清钙（mmol/kg）。 1）对于血清中电解质浓度的测定，使用了多种方法：钠、钾：火焰原子发射光谱法、样品稀释后的离子选择性电极法、酶法；氯：库仑法、化学反应后的吸收光谱法、酶法；钙、镁：火焰原子吸收光谱法、火焰原子发射光谱法（钙）、化学反应后的吸收光谱法、酶法（镁）。如果不知道个体样本的水浓度或脂质和蛋白质浓度，就无法对血清中的钠和氯离子浓度进行安全且明确的医学解读。对于全血清中的钙浓度，情况也是如此——尽管原因有所不同。相关离子的参考区间仅适用于那些在无电解质区室大小方面“正常”的样本，并且——取决于方法——适用于复合结合离子的量。 2）对于血清水（或全血的细胞外水相）中钠、钾、钙和镁的“离子化”或“游离”部分浓度的测定，仅适用以下方法：不稀释样品的离子选择性电极法。无需知道个体样本的水浓度就可以对血清水中离子化电解质浓度进行安全的医学解读，因为这些量与无电解质区室的大小无关。（摘要截选至250词）
