脑脊液总钙及离子钙的测定

目的 在不同环境下测定脑脊液离子钙及其影响因素。方法 用离子电极法测定离子钙和用终点法测定总钙。结果 用于血液离子钙的校正公式不适用于脑脊液离子钙的校正。结论 通过实验我们推出了用于脑脊液离子钙的校正公式，并适用于临床检验。     

血浆离子钙测定的实验条件探讨

用离子选择性电极法测定血浆中的离子钙，低浓度（１０～１５Ｕ／ｍｌ血液）的肝素钠抗凝与非抗凝全血的实时测定值无差别，血样放置超过１５分钟后，导致实测结果的明显降低，经ｐＨ校正后，校正钙（ｐＨ７．４）与实时测定值总体上无差别，但个别结果相差较大。离子钙浓度与总蛋白和清蛋白无确定的相关关系，通过总钙和蛋白浓度计算离子钙是不准确的。５６４名健康人实时测定，离子钙的含量范围是１．１４～１．３０ｍｍｏｌ／Ｌ，     

脑脊液总钙及离子钙的测定

目的：在不同环境下测定脑脊液离子钙及其影响因素。方法：用离子电析法测定离子钙和用终点法测定总钙。结果：用于血液离子钙的校正公式不适用于脑脊液离子钙的校正。结论：通过实验推导出了用于脑脊液离子钙的校正公式，并适用于临床检验。     

关于血浆离子钙测定若干问题的解答

关于血浆离子钙测定若干问题的解答徐俊荣，蒋仁礼，马蔡昀（江苏省人民医院检验科，南京２１００２９）１血浆（清）离子钙，总钙和白蛋白之间的关系如何？答：血浆（清）总钙（ＴＣａ２＋）包括蛋白结合钙，有机酸结合钙和离子钙等几个部分，其中只有离子钙（ｉＣａ２＋...     

测定血清结合钙和离子钙的新方法

血清总钙包括和白旦白结合的钙与磷酸根以及枸椽酸根离子结合的钙(这部分结合钙约占总钙的10-12％)离子钙是具有生理活性钙、约占总钙的42-54％，绝对浓度、新生儿为1．0-1．28，成人为1．12-1．30mmol／L。     

孕妇血清总钙与离子钙的检测

孕妇血清总钙与离子钙的检测马蔡昀，徐俊荣，蒋仁礼（江苏省人民医院检验科，南京２１００２９）孕妇血清总钙（ＴＣａ２＋）降低曾有报道，但对孕妇血清离子钙（ｉＣａ２＋）水平的变化，国外报道各不相同，国内因钙离子选择性电极尚未普及，未见报道。我们在这方面做了...     

血清离子钙分析有关问题的探讨

探讨了离子钙分析的有关问题，电极法测定Ｃａ＾２＋线性良好，线性相关ｒ＝０．９９８４。测定３０例血清标本，Ｃａ＾２＋占ＴＣａ的４４．９％￣４９．５％。平均４８．１７％。血清Ｃａ＾２＋与ｐＨ呈高度负相关，ｒ＝－０．９９６１，经２０例随机样品测定，血清ｐＨ每增加０．１ｐＨ单位，Ｃａ＾２＋浓度减少４．８％￣５．４％，平均为５．２％。离子钙分析临床意义优于总Ｃａ，应推广应用。     

离子强度对血液中离子钙测定的影响

目的探讨离子强度对血液中离子钙测定的影响.方法测定不同离子强度的混合血清和标准液中的离子钙浓度.结果钙离子浓度随着混合血清或标准液中NaCl浓度的升高(112-200mmol/L)而升高,当NaCl浓度为112～140mmol/L时,这种变化尤其明显.结论血液中离子强度的增加对钙离子的测定产生正误差.     

离子强度对血液中离子钙测定的影响

目的：探讨离子强度对血液中离子钙测定的影响。方法：测定不同离子强度的混合血清和标准液中的离子钙浓度。结果：钙离子浓度随着混合血清或标准液中NaCl浓度的升高（112－200mmol/L)而升高，当NaCl浓度为112－140mmol/L时，这种变化尤其明显。结论：血液中离子强度的增加对钙离子的测定产生正误差。     

低钙透析液用于高钙血症患者血液透析的观察及护理

总结低钙透析液用于高钙血症患者血液透析的观察及护理.7例使用低钙透析液透析后血钙下降明显,护理措施主要是开展健康知识宣教,严密观察有无出现不良反应,及时监测实验室指标的变化.低钙液透析3.5 h后改用钙离子浓度1.4 mmol/L透析液透析可预防低血压、肌痉挛的发生.     

Effect of acute bile acid pool depletion on total and ionized calcium concentrations in human bile*

Abstract. Although calcium salts are important components of gallstones, there are few data on the total and ionized calcium content of human bile. Therefore, in 14 fasting T-tube patients studied 7–11 days after cholecystectomy, we measured bile flow, bile acid [BA], total [Ca_TOt] and free ionized [Ca⁺⁺] calcium concentrations, in 20–30 min bile collections during acute BA pool depletion induced by 6–8 h of continuous bile drainage. During washout of the BA pool there were parallel falls in bile flow, BA output and total calcium output (correlation coefficients ranging from 0.59 to 0.99; P< 0.02–0.001). In 12 of the 14 patients, [Ca_TOT] also fell (from 1.84 ± 0.29 to l.32 ± 0.34 mmol L^-1) in parallel with [BA] (from 34.0 ± 14.0 to 8.2 ± 8.0 mmol L^-1; r= 0.75–0.98; P<0.005). In contrast, biliary [Ca⁺⁺] remained virtually unchanged. These data suggest that the BAs are linked to the bound, rather than to the free, ionized, fraction of biliary calcium, which is consistent with in vivo calcium binding by BAs. A model is proposed in which BA-induced biliary calcium secretion results from (i) bile acid-induced water flow via solvent drag; and (ii) calcium binding in the bile canaliculus by bile acids, which induces paracellular diffusion of Ca⁺⁺, thereby maintaining [Ca⁺⁺] independent of [BA].     

Serum ionized magnesium and calcium levels in adult patients with seizures

Objective. Prior studies have been equivocal about whether or not serum levels of the divalent ions calcium and magnesium are altered during different types of seizures. Magnesium is a potential modulator of seizure activity because of its ability to antagonize the excitatory calcium influx through the N‐methyl‐D‐aspartate (NMDA) receptor. We hypothesize that serum ionized levels of calcium (Ca²⁺) and magnesium (Mg²⁺) would be altered significantly during certain types of seizures. Material and methods. A convenience sample of seizure patients presenting to an emergency department (ED) were enrolled in this prospective study. Novel ion‐selective electrodes were used to measure Ca²⁺ and Mg²⁺. Data were reported as mean values±standard deviations. Group comparisons were analyzed by ANOVA with post‐hoc testing using the Bonferroni, or the Fisher exact test, where appropriate, α = 0.05 (two‐tailed). Results. Forty‐nine patients with seizure and 32 healthy racially matched controls were included in the study. Seizure patients had a significantly (p<0.001) lower mean Mg²⁺, but not total serum Mg and a significantly (p<0.001) higher Ca²⁺/Mg²⁺ ratio than that in controls. Conclusions. We were able to show significantly lower Mg²⁺ and higher ionized Ca²⁺/Mg²⁺ ratios in seizure patients compared with a racially matched control group.     

Stimulation of arginine vasopressin secretion by a small increase in blood ionized calcium in normal men

Evidence has been provided for an increase in baseline serum corticotrophin (ACTH) levels in response to a rise in circulating ionized calcium (Ca_i) levels within the physiological range. In order to establish whether small Ca_i increments are also able to modify the basal secretion of arginine vasopressin (AVP), we infused calcium gluconate through an intravenous infusion pump in eight healthy male subjects (25–31 years old). Serum Ca_i, ACTH and AVP concentrations were measured every 10 min over an infusion period lasting 90 min. A significant progressive rise in serum Ca_i (baseline: 42 ± 0.9 mg dL⁻¹; 90 min: 47.2 ± 0.9 mg dL⁻¹, P  < 0.001), ACTH (baseline: 30.7 ± 1.3 pg mL⁻¹; mean peak at 80 min: 37.4 ± 2.4 pg mL⁻¹, P  < 0.01) and AVP levels (baseline: 2.1 ± 0.6 pg mL⁻¹; mean peak at 80 min: 3.2 ± 0.5 pg mL⁻¹, P  < 0.01) was observed during calcium infusion. Furthermore, a significant positive correlation ( r  = 0.71; P  < 0.001) was observed between ACTH and AVP responses to calcium infusion at 60, 70, 80 and 90 min. These data demonstrate that AVP secretion is stimulated by a slight rapid increase in serum Ca_i levels even though absolute serum Ca_i levels remain within the normal range. In addition, the positive correlation between Ca_i-induced ACTH and AVP increments suggests that AVP plays a releasing role on ACTH secretion during calcium infusion.     

The Q-oTc and Q-Tc interval and ionized calcium in newborns

Summary. Ionized calcium (CaF), Q-oT_c and Q-T_c intervals were determined in 31 full-term healthy newborns, 12 infants subjected to blood exchange transfusion (ET) and 10 infants with verified clinical hypocalcaemia. There was no significant correlation between CaF values and QT intervals. The large fluctuations in CaF during ET did not correspond to any similar change in Q-oT_c or Q-T_c intervals. The Q-oT_c interval was slightly longer in the hypocalcaemic and the blood exchanged groups compared to controls. The Q-T_c interval was somewhat longer in the ET group. The differences in mean values for QT intervals were fairly small and the ranges wide. ECG findings lack practical implications in diagnosing and following neonatal hypocalcaemia and we therefore recommend the measurement of CaF as a guideline.     

Effects of propranolol and verapamil on plasma ionized calcium and parathyroid hormone in short-term intense isokinetic leg exercise

Summary. Physical exercise, beta-adrenergic stimulation and calcium channel blockade can affect calcium homeostasis. The present study investigated, in eight healthy males, the effects of orally administered propranolol or verapamil during a 2-min maximal, isokinetiC., leg exercise. Immediately after exercise the plasma ionized calcium concentrations were increased, in control and drug tests, by 5–6%, and within 5 min of recovery they were almost returned to baseline. Serum parathyroid hormone (PTH) concentrations were unchanged at termination of exercise, but they increased during the first 5 min of recovery, coincident with the decline in calcium concentrations, which, however, were still elevated. Neither verapamil nor propranolol selectively changed basal or exercise plasma ionized calcium or serum PTH concentrations. Muscle strength, blood pH, lactate concentrations and plasma volume changes were not affected by any drug. Verapamil did not have any specific effect on the concentrations of plasma magnesium, phosphate, potassium or sodium while propranolol increased the concentrations of plasma potassium and decreased those of phosphate during exercise as well as recovery.     

Decreased serum concentration of ionized calcium in insulin-dependent human diabetes mellitus

Abstract. Low serum ionized calcium concentrations were observed in twenty-five insulin dependent diabetic outpatients compared with twenty-three age-matched normal subjects: mean 1.16 mmol/l (SEM 0.01) versus 1.20 mmol/l (0.01), P < 0.002. Despite this, there was no compensatory increase in serum concentrations of immunoreactive parathyroid hormone, nor was serum total calcium decreased in the diabetic patients. Serum magnesium was significantly decreased in the diabetics compared with normals: mean 0.75 mmol/l versus 0.83 mmol/l, P < 0.001. No significant correlation could be demonstrated between serum magnesium and serum ionized calcium or parathyroid hormone in the diabetic patients.
Since no significant correlations were observable between serum ionized calcium and indices of diabetes control, the etiology and pathogenesis of decreased serum calcium ion in insulin-dependent human diabetes mellitus remain unknown.     

急性肾缺血再灌注大鼠肾细胞游离钙水平与细胞凋亡的研究

目的观察缺血再灌注损伤对肾细胞游离钙([Ca2+]i)水平和细胞凋亡的影响。方法采用摘除左肾,钳夹大鼠右侧肾蒂,建立急性缺血再灌注肾损伤模型,应用Fura-2/AM荧光指示剂测定缺血再灌注大鼠肾细胞[Ca2+]i水平,流式细胞术检测肾细胞凋亡率。结果缺血再灌注不同时期肾细胞呈现不同程度Ca2+超载,与对照组相比差异显著(P0.01);肾细胞凋亡率增高,与对照组相比差异显著(P0.05、P0.01),有正相关趋势。结论缺血再灌注不同时期肾细胞游离钙([Ca2+]i)水平增高,并与肾细胞凋亡率有正相关趋势,再灌注时间与肾细胞Ca2+超载呈正相关,提示再灌注损伤在加重细胞钙超载同时增加了肾组织细胞凋亡,可能是再灌注损伤肾功能障碍的重要原因。     

Serum ionized magnesium levels and serum ionized calcium/ionized magnesium ratios in women with menstrual migraine

OBJECTIVE: It has been suggested that magnesium deficiency may play an important role in menstrual migraine and that the serum ionized calcium (ICa2+)/ionized magnesium (IMg2+) ratio is important in migraine headache. Studies were designed to test these hypotheses. DESIGN: We prospectively evaluated 270 women seen at a headache clinic and in 61 women with menstrual migraine measured IMg2+, total magnesium, and ICa2+ levels so as to calculate the ICa2+/IMg2+ ratio. RESULTS: The incidences of IMg2+ deficiency were 45% during menstrual attacks, 15% during nonmenstrual attacks, 14% during menstruation without a migraine, and 15% between menstruations and between migraine attacks. The serum ICa2+ levels were within our reference range, but the ICa2+/IMg2+ ratio was elevated (P<.01) in menstrual migraine. CONCLUSIONS: The high incidence of IMg2+ deficiency and the elevated ICa2+/IMg2+ ratio during menstrual migraine confirm previous suggestions of a possible role for magnesium deficiency in the development of menstrual migraine.     

Heparinization of samples for plasma ionized calcium measurement

Maintenance of normal plasma ionized calcium concentration forms part of the management of the critically ill patient; it is, therefore, important to measure accurately plasma ionized calcium. We have compared the ionized calcium concentration of blood samples heparinized with a carefully measured amount of heparin with that of blood samples heparinized in the conventional fashion. The amount of heparin in the deadspace of a syringe was demonstrated to artifactually lower the plasma ionized calcium concentration. Samples for plasma ionized calcium measurement should be heparinized with a measured quantity of heparin, since the conventional technique introduces an unknown and probably excessive quantity of heparin into the syringe deadspace.