不同钙剂对男性多次双份机采献血者影响的研究

目的研究口服碳酸钙和葡萄糖酸钙对男性多次机采献血者双份机采中血清钙、磷和甲状旁腺素(PTH)的影响。方法随机抽取男性多次机采献血者77例,随机的分为3组:未补钙组,葡萄糖酸钙组(采前20 min口服葡萄糖酸钙4支,元素钙360 mg),碳酸钙组(采前20 min口服碳酸钙2片,元素钙1 200 mg),检测献血者机采前-20 min)、机采开始(0 min)、机采中(40 min)、后(80 min)血清钙、磷和PTH含量,观察献血者的柠檬酸盐抗凝剂相关反应。结果双份机采后,3个组的钙分别为(2.13±0.06),(2.23±0.07),(2.23±0.07)mmol/L;3个组双份机采后的PTH分别为(153±57),(121±35),(104±40)pg/L;机采中和机采后3组的钙、PTH比较,均为P0.01;采集后碳酸钙组与葡萄糖酸钙组比较,血清钙和PTH比较,葡萄糖酸钙、碳酸钙组与未补钙组比较,轻度抗凝剂反应的发生率均为P0.05。结论口服碳酸钙和葡萄糖酸钙能有效稳定机采中血清钙,PTH的波动,献机采前20 min口服碳酸钙是值得推荐的。     

口服葡萄糖酸钙对单采血小板献血者甲状旁腺素及钙、磷的影响

目的观察口服葡萄糖酸钙及不同口服方式对单采血小板前后献血者血清甲状旁腺素（PTH）及钙、磷浓度变化的影响。方法选择单采血小板献血者57名，分为未补钙组（n=26）、采前一次口服钙组（n=19）和采集过程中少量多次口服钙组（n=12），分别检测血小板采集前后血清PTH和钙、磷离子浓度。并选择献全血组20名。结果单采血小板后57名献血者血清中PTH浓度均明显升高，血清磷明显降低，与采集前比较差异有统计学意义（P〈0.05）；未补钙组与一次口服钙组单采前后PTH浓度升高的差异有统计学意义（t=2.167，P〈0.05）；未补钙组与少量多次口服钙组单采前后PTH浓度升高幅度的差异无统计学意义（t=0.403，P〉0.05）。单采组采前PTH浓度高于献全血组（t=2.083，P值均〈0.05），血清钙、磷的浓度低于献全血组（t值分别为2.069，2.162，P值均〈0.05），但仍在正常范围内。结论单采血小板前献血者口服一定的葡萄糖酸钙可以降低机采过程中血清PTH升高的幅度，但在血小板采集过程中少量多次口服钙并不能降低血清PTH升高的幅度。     

长期多频次机采献血者体内钙磷代谢变化及口服葡萄糖酸钙改善柠檬酸盐抗凝剂不良反应的护理研究

目的：调查研究深圳市长期多频次机采献血者体内钙磷代谢变化及口服葡萄糖酸钙改善柠檬酸盐抗凝剂不良反应护理。方法采用随机数字表法将56例献血者按照含有口服葡萄糖酸钙的方式,分为采集前补钙组20例,采集中补钙组19例,未补钙组17例。结果跟踪观察三组献血者的血清钙水平、磷水平以及PTH水平,均出现不同变化。在采集后60 min中未补钙组中血清PTH为（160.23±29.76）pg／ml,采集中补钙组为（121.75±43.12）pg／ml,采集前补钙组为（104.75±20.99）pg／ml,三者相比差异有统计学意义（ P＜0.05）。结论献血者机采前10 min口服葡萄糖酸钙,是补充钙剂的最佳时机,有利于改善献血者低钙症状,提高机采过程中的舒适度,确保献血安全。     

口服葡萄糖酸钙对单采血小板过程中献血者血清钙、镁和甲状旁腺素的影响

目的了解单采血小板过程中血清镁的变化情况和固定单采血小板献血者预防性口服补钙后其钙、镁和血清甲状旁腺素的变化情况。方法选择本中心固定单采血小板献血者49人,随机分为口服补钙组(n=20):采集血小板前口服葡萄糖酸钙20 m L(含钙共180 mg);未补钙组(n=29):采集血小板前未口服葡萄糖酸钙。采用全自动生化分析仪和化学发光免疫分析仪分别检测献血者在机采血小板0、30、60、90 min留取的血液标本中的血清钙、镁和甲状旁腺素含量,比较2组单采血小板献血者这3项指标的差异。结果机器采集血小板0、30、60、90 min时,补钙组和与未补钙组献血者的血清钙(mmol/L)分别为2.44±0.25 vs 2.39±0.21、2.31±0.18 vs 2.19±0.20、2.35±0.27 vs 2.25±0.22、2.33±0.27 vs 2.24±0.20;血清镁(mmol/L)分别为0.76±0.19 vs 0.74±0.19、0.72±0.16 vs 0.69±0.20、0.73±0.18 vs 0.71±0.19、0.73±0.16 vs 0.71±0.18;甲状旁腺素(pg/m L)分别为43.43±20.78 vs 48.16±42.31、166.26±88.77 vs 154.22±71.98、137.79±64.73 vs 138.77±62.99、104.09±76.16 vs 99.83±62.20。2组之间只有血清钙水平在30 min时补钙组明显高于未补钙组(P0.05)。结论单采血小板过程中存在血清镁的降低,预防性口服葡萄糖酸钙能缓解低钙血症,但对低镁血症影响有限。     

尿毒症患者血清甲状旁腺激素及钙与血小板参数的关系探讨

目的探讨尿毒症患者血清甲状旁腺激素及钙与血小板参数的关系,了解尿毒症患者血小板功能障碍的产生原因。方法选择108例临床确认尿毒症患者作为病例组,100健康体检标本作为对照组。采用化学发光法检测甲状旁腺激素(PTH),比色法检测血清钙离子(Ca2+)浓度,Bayer AVDIA2120全自动五分类血细胞分析仪检测PLT、MPV、MPC、MPM以及L-Pt。将病例组以PTH300(pg/ml)为界,分为PTH300(pg/ml)组和PTH≤300(pg/ml)组。再将病例组以Ca2+浓度水平2.1mmol/L为界分为Ca2+2.1mmol/L组和Ca2+≤2.1mmol/L组。不同组间血小板的参数检测结果比较采用t检验进行统计学分析。结果尿毒症组血液中具有高水平的PTH和低钙血症,PLT、MPV、MPC、MPM检测结果均低于正常对照组。病例组以PTH300(pg/ml)为界分组检测血小板参数显示,PTH300(pg/ml)组的MPC、MPM显著低于PTH≤300(pg/ml)组的结果(P0.05)。病例组以Ca2+浓度水平2.1mmol/L为界分组检测血小板参数显示,Ca2+2.1mmol/L组的PLT明显高于Ca2+≤2.1mmol/L组的结果(P0.05)。MPV、MPC、MPM以及L-Pt检测结果无显著性差异(P0.05)。结论尿毒症患者高PTH水平可能是影响血小板功能的原因之一,Ca2+浓度水平可能对血小板数量的产生有一定影响。     

单采血小板前后献血者血清甲状旁腺素及电解质的变化

目的观察单采血小板前后献血者血清甲状旁腺素及电解质浓度的变化。方法选择单采血小板献血者45名,分为补钙组(n=11)和未补钙组(n=34),分别检测血小板采集前后血清甲状旁腺素(PTH)和钙、磷、钾、钠、镁离子浓度;献全血组(n=24)。结果单采后补钙组PTH浓度有统计学意义(t=2.472,P<0.05),未补钙组单采后磷浓度升高(t=3.191,P<0.05);单采血小板献血者采前血清磷、钙、钠的浓度低于对照组(t值分别为2.477,2.349和2.064,P<0.05),但仍在正常范围内。结论单采血小板会引起献血者血钙浓度短暂降低,但机体可自身迅速调节,不必常规补钙;单采血小板献血者采集前血清磷、钙、钠的浓度低于全血献血者。     

血液灌流对维持性血透患者血清甲状旁腺素的清除作用

[摘要] 目的 观察血液透析(HD)和血液透析串联血液灌流(HD+HP)对维持性血液透析患者血清甲状旁腺素(PTH)的清除效果。方法 将20例稳定的维持性血液透析患者随机分为2组：HD组及HD+HP组，治疗前、后分别抽静脉血测定血清肌酐（Scr）、尿素氮（BuN）血清磷及PTH。结果 HD组治疗后PTH及血清磷分别由 987.86±445.31pg/ml，2.40±0.31mmol/L降至973.29±424.36pg/ml, 1.87±0.10mmol/L，PTH清除率为 7.33±2.89%，治疗前后无明显差异（P＞0.05），血清磷治疗前后差异显著（P＜0.05）；HD+HP组治疗后PTH由 998.38±431.96pg/ml降至749.13±543.13pg/ml，单次治疗清除率为39.73±27.53% ，治疗前后差异显著(P＜0.05)，血清磷由治疗前2.39±0.37mmol/L降至1.34±0.12mmol/L，差异显著并明显高于HD组（P＜0.05）。结论 HD+HP可以有效清除PTH及磷，HD可以有效清除血清磷但不能有效清除PTH。     

肺结核并发糖尿病患者外周血白细胞介素-22含量检测

目的 检测肺结核并发糖尿病(PPTDM)患者外周血血清IL-22含量并分析其意义。方法 ELISA检测30例PPTDM患者、30例肺结核(PTB)患者、30例糖尿病(DM)患者和30例健康志愿者(HV)血清IL-22含量并分析其意义。结果 PPTDM组血清IL-22含量(54.4±4.81 pg/ml)显著低于DM组(72.36±5.12 pg/ml)和HV组(68.32±3.08 pg/ml),差异均有统计学意义(t=2.557,P=0.013; t=2.437,P=0.018)。PPTDM组血清IL-22含量高于PTB组(45.36±5.88 pg/ml),但差异无统计学意义(t=1.190,P=0.239)。不同形式肺结核并发糖尿病患者血清IL-22含量检测结果中,先患肺结核后患糖尿病(PTB-DM)组血清IL-22含量(64.62±8.59 pg/ml)显著高于先患糖尿病后患肺结核(DM-PTB)组(44.21±2.68 pg/ml),差异有统计学意义(t=2.267,P=0.031)。结论 IL-22在PPTDM疾病发生中可能具有重要作用。     

两种钙剂对首次和固定献血者Ca2+和PTH变化的探讨

目的 探究葡萄糖酸钙口服液和乳酸钙颗粒剂对首次和固定机采血小板献血者血清钙和甲状旁腺素(PTH)变化的影响。方法 2020年7月～11月招募机采血小板首次献血志愿者84例和固定献血志愿者35例为研究对象,将首次献血者平均分成2组,每组各42例(男28、女14例),和固定献血者参与2组钙剂实验,每个实验周期≥14d,第1实验周期2组献血者采前20 min服用葡萄糖酸钙口服液(葡萄糖酸钙2支,补钙量180 mg),第2实验周期2组献血者采前20 min服用乳酸钙颗粒冲剂(乳酸钙颗粒剂2.5 g/袋,补钙量180 mg),检测2组献血者采集前(20 min)、采集开始(0 min)、采集中(20 min)、采集中(40 min)血清钙和甲状旁腺素含量,比较2组献血者在采集过程中枸橼酸钠中毒反应情况,评估2种钙剂的使用效果。结果 2补钙组首次和固定献血者血总钙均于采集20 min开始明显下降,并在采集40 min趋向平稳,PTH的总体水平则呈先迅速上升后缓慢回降的趋势。固定和首次献血者补钙前Ca²⁺变化比较,P<0.01;采集20 min Ca²⁺     

不同方式治疗维持性血液透析患者难治性继发性甲状旁腺功能亢进的对比性研究

目的探讨帕立骨化醇联合盐酸西那卡塞治疗难治性继发性甲状旁腺功能亢进(secondary hyperparathyroidism,SHPT)的有效性及安全性;同时与甲状旁腺切除术(parathyroidectomy,PTX)进行疗效对比。方法回顾性分析2013年12月至2016年6月在哈尔滨医科大学附属第一医院血液净化中心行维持性血液透析(maintenance hemodialysis,MHD)的难治性SHPT患者,PTX组11例,帕立骨化醇联合西那卡塞(药物)组13例,记录年龄、透析龄、治疗前1周、治疗后1周、1月、3月及6月血清钙(calcium,Ca)、磷(phosphorus P)、钙磷乘积(Ca×P)、全段甲状旁腺素(intact parathyroid hormone,i PTH)水平、碱性磷酸酶(alkaline phosphatase,AKP)及临床症状,根据复查结果调整药量。比较两组相同时间点及不同治疗方式上述指标。结果与治疗前相比,PTX组治疗后1周、1月、3月及6月血清Ca、Ca×P、i PTH及AKP水平降低,差异有统计学意义(血清Ca:F=18.908,P0.001;Ca×P:F=21.884,P0.001;血清i PTH:F=24.251,P0.001;血清AKP:F=95.459,P=0.001);药物组治疗后1月、3月及6月血清Ca及i PTH水平显著降低,差异有统计学意义(血Ca:F=7.671,P0.001;血清i PTH:F=4.037,P=0.006);血清P及AKP水平整个治疗期间差异不显著(血清P:F=0.378,P=0.824;血清AKP:F=0.718,P=0.583)。治疗6月后两组(PTX组比药物组)血清Ca[(2.40±0.15)mmol/L比(2.44±0.14)mmol/L、t=-0.797,P=0.434]、P[(1.98±0.25)mmol/L比(2.20±0.39)mmol/L,t=-1.616,P=0.120]及Ca×P[(4.74±0.27)mmol~2/L~2比(5.38±1.02)mmol~2/L~2,t=-1.740,P=0.096]及AKP[(85.50±38.43)比(113.33±36.83)U/L,t=-1.815,P=0.083]无差异;血清i PTH差异显著[(525.81±242.12)pg/ml比(809.22±372.87)pg/ml,t=-2.161,P=0.042]。结论帕立骨化醇联合盐酸西那卡塞与PTX均能不同程度治疗难治性SHPT,PTX能够更快的改善高Ca、P及骨代谢,远期疗效需扩大样本量及观察时间进一步评价。     

Hypocalcemic symptoms during plateletpheresis using the COBE Spectra: A comparison of oral combination of 600mg calcium+300mg magnesium+100IU vitamin D3 vs. a 1000mg calcium in symptomatic donors.

BACKGROUND: The aim of this study was to find an effective treatment for hypocalcemic symptoms during plateletpheresis and to evaluate if a combination of calcium, magnesium and vitamin D3 is more effective in comparison to routine calcium supplementation. MATERIAL AND METHODS: A study group consisting of 10 donors, having a history of previous hypocalcemic symptoms during plateletpheresis, donated platelets twice in a one-month period. During the first donation combination tablets (600mg Ca+300mg Mg+100IU vitamin D3) were used to treat hypocalcemic symptoms while routine treatment calcium carbonate tablets (1000mg Ca) were used during the second donation. If symptoms persisted after 10min the same dose was repeated. A control group, with no supplementation, consisting of five donors, with no history of hypocalcemic symptoms, were included. Donor subjective symptoms were graded and recorded on four occasions: at the start of plateletpheresis, when symptoms appeared, 10min after the first tablet and at the end of donation. Samples for analysis of ionized calcium (iCa), magnesium and potassium were also taken at the same occasions. RESULTS: All donors from the study group experienced minor or medium hypocalcemic symptoms and needed a second dose of supplementation. Calcium carbonate tablets completely relieved the hypocalcemic symptoms in six donors, it had no effect on three donors and one donor experienced aggravated symptoms. The combination tablets completely relieved the symptoms in three donors, one donor experienced a partial relief and six donors had no relief of symptoms. There were no significant differences in iCa, potassium and magnesium levels were noted in the study group irrespective of which tablets were used for treatment of hypocalcemic symptoms. After plateletpheresis the median iCa levels declined by 30% and potassium levels declined by 3-11% in all donors while the magnesium levels were not significantly affected. There was no correlation between the presence of symptoms and the changed levels of iCa or magnesium. CONCLUSION: Addition of magnesium and vitamin D3 to calcium seems to have no beneficial effect in the treatment of hypocalcemic symptoms in plateletpheresis donors.     

Randomized placebo-controlled study of oral calcium carbonate supplementation in plateletpheresis: II. Metabolic effects

BACKGROUND: The metabolic effects of oral calcium (Ca) supplementation during plateletpheresis were evaluated in a randomized, placebo-controlled trial. STUDY DESIGN AND METHODS: Twenty-three donors underwent four plateletpheresis procedures each, receiving in random order, elemental Ca (Ca) 1 or 2 g orally, or a corresponding placebo, 30 minutes before donation. Ten of these donors underwent a fifth procedure using a 4-g Ca dose. All procedures were performed at a fixed citrate infusion rate of 1.5 mg per kg per minute. RESULTS: Oral Ca induced dose-sensitive changes in parathyroid hormone (iPTH), total (tCa), and ionized (iCa) calcium levels. Compared to placebo, the greatest improvement in tCa and iCa levels occurred after the 2-g Ca dose (tCa of 73, 89, and 25% above placebo levels at 60 min, using 1, 2, and 4 g of oral Ca, respectively). Twenty-four hours after apheresis, serum tCa and iCa levels were higher, and iPTH levels lower, in donors who received oral Ca rather than placebo. Marked increases in urinary Ca and magnesium (Mg) excretion occurred at the completion of apheresis, were unaffected by Ca dose, and returned to baseline within 24 hours. Plateletpheresis also induced significant changes in serum alkaline phosphatase, 1,25-dihydroxyvitamin D, and osteocalcin levels immediately and at 24 hours after apheresis. CONCLUSION: Plateletpheresis induces marked acute metabolic effects, with sustained changes evident up to 24 hours after the completion of apheresis. Oral Ca supplementation exerts a significant but clinically modest impact on selected laboratory variables associated with these effects. Further studies are indicated to examine the long-term impact of plateletpheresis, with or without Ca supplementation, on donor Ca balance and bone density.     

碳酸钙D3咀嚼片联合唑来膦酸注射液治疗老年男性骨质疏松症的临床效果

目的分析碳酸钙D3咀嚼片联合唑来膦酸注射液治疗老年男性骨质疏松症的临床效果。方法回顾性选取本院2018年1月至2020年1月收治的100例老年男性骨质疏松症患者的临床资料,依据治疗方法将其分为联合治疗组(50例,碳酸钙D3咀嚼片联合唑来膦酸注射液治疗)和单独治疗组(50例,单独碳酸钙D3咀嚼片治疗)。比较两组患者的血钙、血磷、骨代谢相关生化指标水平、骨密度、临床疗效及不良反应发生情况。结果治疗后,两组的血钙、血磷、BGP、BAP水平均升高,β-CTX、TRAP-5b水平均降低,且联合治疗组明显优于单独治疗组(P<0.05)。治疗后,联合治疗组腰椎L_2~4、股骨颈、股骨大转子、Ward三角区的骨密度均明显高于单独治疗组(P<0.05)。联合治疗组的治疗总有效率为94.00%,明显高于单独治疗组的80.00%(P<0.05)。两组的不良反应总发生率比较,差异无统计学意义(P>0.05)。结论碳酸钙D3咀嚼片联合唑来膦酸注射液治疗老年男性骨质疏松症的临床效果显著,且安全性高。     

Randomized placebo-controlled study of oral calcium carbonate administration in plateletpheresis: I. Associations with donor symptoms

BACKGROUND: The effect of oral calcium (Ca) supplements in preventing citrate-induced symptoms during plateletpheresis was evaluated in a randomized, blinded, placebo-controlled trial. STUDY DESIGN AND METHODS: Twenty-three donors (12 men, 11 women) underwent four plateletpheresis procedures each, ingesting either 1 or 2 g of oral Ca carbonate or an equivalent placebo 30 minutes before donation. Ten of these subjects subsequently ingested 4 g of open-label Ca before a fifth procedure. All procedures were conducted at the same citrate infusion rate (1.5 mg/kg/min) for 90 minutes. RESULTS: Ingestion of 2 g of oral Ca resulted in a significant reduction in the severity of paresthesias and a significant, though modest, increase in serum ionized calcium (iCa), but no significant improvement in total symptom scores, compared to placebo. Minimal effects were seen with the 1-g dose. The two factors most highly correlated with development of severe symptoms were decreased levels of iCa and ionized magnesium (iMg) at 30 minutes into apheresis. Lower preapheresis serum albumin, creatinine, vitamin D, iMg, and total Mg concentrations were also significantly associated with symptoms. Women experienced more frequent and severe symptoms than men, however, gender was not associated with symptoms after adjustment for lower serum albumin, creatinine, and Mg levels. Ingestion of 4 g of Ca offered no improvement in symptoms or iCa levels compared with the 2-g dose. CONCLUSION: Prophylactic oral Ca was associated with modest improvements in citrate-induced symptoms and laboratory parameters. Baseline albumin and Mg levels were strongly predictive of the development of symptoms. In donors with a prior history of uncomfortable citrate-related effects, a 2-g oral Ca dose before apheresis is recommended.     

低钙透析液对维持性血液透析患者钙磷代谢及甲状旁腺激素的影响

目的探讨低钙透析液对非低钙血症维持性血液透析患者的钙磷代谢以及甲状旁腺激素的影响。方法将60例非低钙血症维持性血液透析患者随机分为观察组与对照组,观察组采用低钙透析液(Ca~(2+)浓度为1.25 mmol/L),对照组采用常规透析液(Ca~(2+)浓度为1.50 mmol/L),比较2组患者的疗效。结果治疗后,观察组患者血清T-Ca、T-Ca×P显著下降,血清i PTH显著升高(P0.05);对照组患者血清T-Ca、T-Ca×P显著升高,血清i PTH显著下降(P0.05)。观察组患者血清T-Ca、T-Ca×P均显著低于对照组,血清i PTH均显著高于对照组(P0.05)。治疗6个月后,观察组患者血清hs-CRP显著低于对照组(P0.05)。2组患者不良反应发生率无显著差异(P0.05)。结论非低钙血症维持性血液透析患者应用低钙透析液可以降低血清高钙负荷,改善甲状旁腺过度抑制状态与心血管炎症状态。     

Evidence that blood ionized calcium can regulate serum 1,25(OH)2D3 independently of parathyroid hormone and phosphorus in the rat.

This study asks whether arterial blood ionized calcium concentration (Ca++) can regulate the serum level of 1,25-dihydroxy-vitamin D3 [1,25(OH)2D3] independently of serum phosphorus and parathyroid hormone (PTH). We infused either PTH (bovine 1-34, 10 U/kg body wt/h) or saline into awake and unrestrained rats for 24 h, through a chronic indwelling catheter. PTH raised total serum calcium and arterial blood ionized calcium, yet serum 1,25(OH)2D3 fell from 35 +/- 6 (mean +/- SEM, n = 10) with saline to 12 +/- 3 pg/ml (n = 11, P less than 0.005 vs. saline). To determine if the decrease in serum 1,25(OH)2D3 was due to the elevated Ca++, we infused PTH into other rats for 24 h, along with varying amounts of EGTA. Infusion of PTH + 0.67 micron/min EGTA reduced Ca++, and 1,25(OH)2D3 rose to 90 +/- 33 (P less than 0.02 vs. PTH alone). PTH + 1.00 micron/min EGTA lowered Ca++ more, and 1,25(OH)2D3 increased to 148 +/- 29 (P less than 0.01 vs. saline or PTH alone). PTH + 1.33 micron/min EGTA lowered Ca++ below values seen with saline or PTH alone, and 1,25(OH)2D3 rose to 267 +/- 46 (P less than 0.003 vs. all other groups). Thus, during PTH infusion lowering Ca++ with EGTA raised 1,25(OH)2D3 progressively. There were no differences in serum phosphorus concentration or in arterial blood pH in any group infused with PTH. The log of serum 1,25(OH)2D3 was correlated inversely with Ca++ in all four groups infused with PTH (r = -0.737, n = 31, P less than 0.001), and also when the saline group was included (r = -0.677, n = 41, P less than 0.001). The results of this study indicate that serum 1,25(OH)2D3 may be regulated by Ca++ independent of PTH and serum phosphorus levels in the rat. Since 1,25(OH)2D3 regulates gastrointestinal calcium absorption, there may be direct feedback control of 1,25(OH)2D3, by its regulated ion, Ca++.     

Calcium absorption in children estimated from single and double stable calcium isotope techniques

In order to determine whether the specific activity in a single serum sample estimates calcium absorption, six healthy children participated in a study using stable isotopic calcium tracers, one given orally and the second intravenously. High-resolution, fast atom bombardment mass spectrometry was used to quantify the 44Ca and 42Ca tracers in serum and urine. Subjects ingested 250 mg of calcium (215 mg calcium enriched with 35 mg 44Ca) in the form of a chewable calcium citrate malate tablet with a standard meal, followed 30 min later with an i.v. injection of 42Ca tracer. Blood for tracer determinations was obtained at 90, 120, 150, 180, and 300 min after oral ingestion, and a urine sample was obtained 24 h after oral calcium tracer administration. The average calcium absorption estimated from the ratio of urinary tracers was 41.4 +/- 8.2%. This study indicates that the level of oral tracer in serum taken 150 min post-ingestion is significantly correlated (r = 0.85, p less than 0.05) with calcium absorption, as determined by the tracer levels in the urine. These results show that an oral stable isotopic tracer coupled with a single blood sample can be used to estimate calcium absorption in children.     

Circulating ionized calcium and parathyroid hormone levels following coronary artery by-pass surgery

In critically ill patients, hypocalcaemia is a common finding. Also variable derangements in the normally tight Ca2+-mediated control of the parathyroid hormone (PTH) secretion have been found. Utilizing coronary artery by-pass grafting (CABG) as a standardized model of severe trauma, 18 patients underwent determinations of blood levels of calcium, magnesium (Mg), ionized calcium (Ca2+), serum levels of intact PTH, procalcitonin (PCT) and the proinflammatory cytokines tumour necrosis factor alpha (TNF-alpha) and interleukin-6 (IL-6). Samples were collected before, directly after, the morning after and 5 days after surgery. A significant, but minor, decrease in blood Ca2+ levels (mean 0.04 mmol/L, p<0.05) was seen shortly after CABG, not accompanied by any significant change of serum PTH levels. This alteration of the Ca2+ control of the steady-state PTH levels contrasted with the maintenance of the PTH secretory response to a sequential citrate and calcium infusion (CiCa clamp), which was normal in two patients evaluated in the morning following surgery. Serum Mg levels were transiently increased after operation (+0.25 mmol/L, p<0.001) and correlated to the TNF-alpha (r=0.62, p <0.01) and PCT (r=0.67, p < 0.006) levels in the morning after surgery. Serum levels of IL-6 and TNF-alpha were significantly (p < 0.0001) increased immediately after surgery, while the peak in serum PCT levels (p < 0.001) occurred in the morning after CABG. Serum PTH levels correlated positively with IL-6 (r=0.68, p<0.008) 5 days after surgery. In conclusion, CABG caused a decrease in ionized calcium levels without a rise in steady-state PTH levels, but rapid changes in Ca2+ during CiCa clamping revealed a normal PTH secretory response. These findings might relate to elevated serum Mg levels, while a direct action of TNF-alpha or IL-6 on the PTH release seem less possible.     

Relative bioavailability of calcium from calcium formate, calcium citrate, and calcium carbonate

Calcium is an essential nutrient required in substantial amounts, but many diets are deficient in calcium making supplementation necessary or desirable. The objective of this study was to compare the oral bioavailability of calcium from calcium formate, a new experimental dietary calcium supplement, to that of calcium citrate and calcium carbonate. In a four-way crossover study, either a placebo or 1200 mg of calcium as calcium carbonate, calcium citrate, or calcium formate were administered orally to 14 healthy adult female volunteers who had fasted overnight. After calcium carbonate, the maximum rise in serum calcium ( approximately 4%) and the fall in serum intact parathyroid hormone 1-84 (iPTH) (approximately 20-40%) did not differ significantly from placebo. After calcium citrate, the changes were modestly but significantly (p < 0.05) greater, but only at 135 to 270 min after ingestion. In contrast, within 60 min after calcium formate serum calcium rose by approximately 15% and serum iPTH fell by 70%. The mean increment in area under the plasma concentration-time curve (0-270 min) for serum calcium after calcium formate (378 mg . min/dl) was double that for calcium citrate (178 mg . min/dl; p < 0.01), whereas the latter was only modestly greater than either placebo (107; p < 0.05) or calcium carbonate (91; p < 0.05). In this study, calcium formate was clearly superior to both calcium carbonate and calcium citrate in ability to deliver calcium to the bloodstream after oral administration. Calcium formate may offer significant advantages as a dietary calcium supplement.