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Albert SG, Scott Isbell T. Reconsideration of "Albumin Corrected Total calcium" Determinations: Potential Errors in the Clinical Management of Disorders of Calcium Metabolism. Clin Chim Acta 2023; 544:117353. [PMID: 37076097 DOI: 10.1016/j.cca.2023.117353] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Revised: 04/04/2023] [Accepted: 04/12/2023] [Indexed: 04/21/2023]
Abstract
BACKGROUND The formula, referenced in major textbooks, for albumin corrected calcium [Calcium(alb)] may not accurately depict ionized calcium [ICa]. We evaluated the accuracy of unadjusted calcium [Calcium(Unadjusted)] and [Calcium(alb)], and developed a protocol for local laboratory adjustment of calcium for albumin. METHODS Laboratory data were obtained from an electronic health record. Assessments were accuracy, false positive, and false negative rates. Clinical reliability was defined in "error zones" for calcium [Ca]: Zone A =Ca(normal), ICa(low) ; Zone B =Ca(low), ICa(normal) ; and Zone C =Ca(normal), ICa(high), Zone D=Ca(high), ICa(normal). RESULTS A linear regression from 468 laboratory tests was used to derive a formula for "revised corrected calcium" [Calcium (revised)] over a range of albumin concentrations where, [Calcium (revised)] = plasma calcium (mg/dl) + [(4- Albumin (g/d)L)]*(plasma calcium (mg/dl)*0.052)]. [Calcium(alb]] vs [Calcium(Unadjusted)] decreased zone B errors 12%, [95%CI;8-15%], vs 44% [95%CI;37-50%], p <0.001. However, [Calcium(alb]] vs [Calcium(Unadjusted)] increased zone A error (60%,[95%CI;42-78%], vs 7% [95%CI;1-13%], p <0.001). [Calcium (revised)] decreased zone A errors (15%, [95%CI;6-24%]) vs [Calcium(alb) ] (60% [95%CI;42-78%], p<0.001) and Zone D errors from 9% [95%CI;6-12%] to 2% [95%CI;1:5%, p<0.001]. CONCLUSIONS [Calcium(alb)] is unreliable in hypo- or hypercalcemia. We provide a protocol for locally derived correction of calcium for albumin.
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Affiliation(s)
- Stewart G Albert
- Department of Internal Medicine, Division of Endocrinology and Metabolism.
| | - T Scott Isbell
- Department of Pathology, Division of Laboratory Medicine. Saint Louis University School of Medicine
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2
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Liu B, Dong D, Wang Z, Gao Y, Yu D, Ye S, Du X, Ma L, Cao H, Liu F, Zhang R, Li C. Analysis of influencing factors of serum total protein and serum calcium content in plasma donors. PeerJ 2022; 10:e14474. [PMID: 36523465 PMCID: PMC9745925 DOI: 10.7717/peerj.14474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Accepted: 11/07/2022] [Indexed: 12/14/2022] Open
Abstract
Background and objectives The adverse effects of plasma donation on the body has lowered the odds of donation. The aim of this study was to investigate the prevalence of abnormal serum calcium and total serum protein related to plasma donation, identify the influencing factors, and come up with suggestions to make plasma donation safer. Methods Donors from 10 plasmapheresis centers in five provinces of China participated in this study. Serum samples were collected before donation. Serum calcium was measured by arsenazo III colorimetry, and the biuret method was used for total serum protein assay. An automatic biochemical analyzer was used to conduct serum calcium and total serum protein tests. Results The mean serum calcium was 2.3 ± 0.15 mmol/L and total serum protein was 67.75 ± 6.02 g/L. The proportions of plasma donors whose serum calcium and total serum protein were lower than normal were 20.55% (815/3,966) and 27.99% (1,111/3,969), respectively. There were significant differences in mean serum calcium and total serum protein of plasma donors with different plasma donation frequencies, gender, age, regions, and body mass index (BMI), (all p < 0.05). Logistic regression analysis revealed that donation frequencies, age, BMI and regions were significantly associated with a higher risk of low serum calcium level, and donation frequencies, gender, age and regions were significant determinants factors of odds of abnormal total serum protein. Conclusions Donation frequencies, gender, age, regions, and BMI showed different effects on serum calcium and total serum protein. More attention should be paid to the age, donation frequency and region of plasma donors to reduce the probability of low serum calcium and low total serum protein.
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Affiliation(s)
- Bin Liu
- Institute of Blood Transfusion, Chinese Academy of Medical Sciences & Peking Union Medical College, Chengdu, China
| | - Demei Dong
- Beijing Tiantan Biological Products Co., Ltd, Chengdu, China
| | - Zongkui Wang
- Institute of Blood Transfusion, Chinese Academy of Medical Sciences & Peking Union Medical College, Chengdu, China
| | - Yang Gao
- Beijing Tiantan Biological Products Co., Ltd, Chengdu, China
| | - Ding Yu
- Rongsheng Pharmaceuticals Co., Ltd, Chengdu, China
| | - Shengliang Ye
- Institute of Blood Transfusion, Chinese Academy of Medical Sciences & Peking Union Medical College, Chengdu, China
| | - Xi Du
- Institute of Blood Transfusion, Chinese Academy of Medical Sciences & Peking Union Medical College, Chengdu, China
| | - Li Ma
- Institute of Blood Transfusion, Chinese Academy of Medical Sciences & Peking Union Medical College, Chengdu, China
| | - Haijun Cao
- Institute of Blood Transfusion, Chinese Academy of Medical Sciences & Peking Union Medical College, Chengdu, China
| | - Fengjuan Liu
- Institute of Blood Transfusion, Chinese Academy of Medical Sciences & Peking Union Medical College, Chengdu, China
| | - Rong Zhang
- Institute of Blood Transfusion, Chinese Academy of Medical Sciences & Peking Union Medical College, Chengdu, China
| | - Changqing Li
- Institute of Blood Transfusion, Chinese Academy of Medical Sciences & Peking Union Medical College, Chengdu, China
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Shen B, Hao J, Lin Y, Li X, Yang X, Huang T, Wang J, Jia Y, Zhou J, Wang J. Estrogen-Induced Extracellular Calcium Influx Promotes Endometrial Cancer Progress by Regulating Lysosomal Activity and Mitochondrial ROS. Front Med (Lausanne) 2022; 9:835700. [PMID: 35223931 PMCID: PMC8866192 DOI: 10.3389/fmed.2022.835700] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Accepted: 01/18/2022] [Indexed: 11/13/2022] Open
Abstract
Objective Calcium is present in serum mainly in filterable and bound forms, and Ca2+ is a major key to modulate signaling pathways that control oncogenesis and oncochannels associated with several types of cancer. However, the biological significance of serum calcium and its related mechanism with estrogen in endometrial cancer (EC) still remains elusive. This study aims to ascertain the relationship between serum calcium and clinicopathology in EC. Methods Retrospective assessment of a total of 502 patients diagnosed with EC after surgery in Peking University People's Hospital from 2010 to 2018. Preoperative serum ionized calcium and the albumin corrected calcium was calculated in quartiles for various postoperative clinicopathological characteristics, logistic regression adjusted for potential confounders. Intracellular calcium homeostasis change induced by estrogen was detected by confocal analysis. Downstream pathways were analyzed by transcriptome and proteomics. Mitochondrial Ca2+ and ROS (reactive oxygen species) level was detected by confocal and flow cytometry. Lysosomal morphological and membrane changes were verified by confocal or Western blot assays. Results High level of albumin-corrected serum calcium was significantly correlated with EC clinicopathological characteristics progression include lymph vascular space invasion, lymph nodes metastasis, myometrial invasion, and cervical invasion. Calcium homeostasis regulated by estrogen in EC cells derived from extracellular calcium influx but not the release of the endoplasmic reticulum. Proteomic and bioinformatic analysis revealed the calcium influx might be involved in the regulation of autophagy and mitochondrial-related pathways. Mechanistic investigation demonstrated that calcium influx acted on the function of mitochondrial ROS and lysosomal activity. Conclusion Our findings revealed that serum calcium level was significantly related to poor outcomes. The extracellular calcium influx induced by estrogen was targeted to mitochondrial ROS and lysosome activity, which should be oriented to improve EC therapeutic strategies.
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Affiliation(s)
- Boqiang Shen
- Department of Obstetrics and Gynecology, Peking University People's Hospital, Beijing, China
| | - Juan Hao
- Department of Obstetrics and Gynecology, Peking University People's Hospital, Beijing, China
| | - Yanying Lin
- Center of Reproductive Medicine, Fujian Maternity and Child Health Hospital, Affiliated Hospital of Fujian Medical University, Fuzhou, China
| | - Xingchen Li
- Department of Obstetrics and Gynecology, Peking University People's Hospital, Beijing, China
| | - Xiao Yang
- Department of Obstetrics and Gynecology, Peking University People's Hospital, Beijing, China
| | - Ting Huang
- Department of Obstetrics and Gynecology, Peking University People's Hospital, Beijing, China
| | - Jiaqi Wang
- Department of Obstetrics and Gynecology, Peking University People's Hospital, Beijing, China
| | - Yuanyuan Jia
- Department of Obstetrics and Gynecology, Peking University People's Hospital, Beijing, China
| | - Jingyi Zhou
- Department of Obstetrics and Gynecology, Peking University People's Hospital, Beijing, China
| | - Jianliu Wang
- Department of Obstetrics and Gynecology, Peking University People's Hospital, Beijing, China
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Abstract
PURPOSE OF REVIEW This review provides suggestions for the evaluation of patients with osteoporosis in order to assure that the diagnosis is correct, to identify potentially correctable conditions contributing to skeletal fragility and fracture risk, and to assist in individualizing management decisions. RECENT FINDINGS Some patients who appear to have osteoporosis have another skeletal disease, such as osteomalacia, that requires further evaluation and treatment that is different than for osteoporosis. Many patients with osteoporosis have contributing factors (e.g., vitamin D deficiency, high fall risk) that should be addressed before and after starting treatment to assure that treatment is effective and safe. Evaluation includes a focused medical history, skeletal-related physical examination, assessment of falls risk, appropriate laboratory tests, and rarely transiliac double-tetracycline labeled bone biopsy. Evaluation of patients with osteoporosis before starting treatment is essential for optimizing clinical outcomes.
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Affiliation(s)
- E Michael Lewiecki
- New Mexico Clinical Research & Osteoporosis Center, 300 Oak St. NE, Albuquerque, NM, 87106, USA.
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Lantman MVS, van de Logt AE, Thelen M, Wetzels JF, van Berkel M. Measurement of serum albumin in nephrology: we need to improve. Nephrol Dial Transplant 2020; 37:1792-1799. [PMID: 33367921 DOI: 10.1093/ndt/gfaa375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Indexed: 11/14/2022] Open
Abstract
Serum albumin is a widely used biomarker in clinical nephrology. Serum albumin cut-off values are used to define disease, to predict outcome, and to guide patient care. The available commercial assays to measure serum albumin rely on different analytical principles, all with their own (analytical) specifications. This paper provides an overview of the different clinical applications of serum albumin measurements in nephrology, the (dis)advantages of the available assays and the estimates of the effects of the measurement uncertainty between different assays in clinical decision making. This paper concludes that harmonisation of serum albumin assay results are needed.
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Affiliation(s)
- Marith van Schrojenstein Lantman
- Radboud University Medical Centre, Department of Laboratory Medicine, Nijmegen, The Netherlands.,Amphia Hospital, Department of Laboratory for Clinical Chemistry, part of Result Laboratorium, Breda, The Netherlands.,SKML, Organisation for Quality Assurance of Medical Laboratory Diagnostics, Radboud University, Nijmegen, The Netherlands
| | - Anne-Els van de Logt
- Radboud University Medical Centre, Radboud Institute for Health Sciences, Department of Nephrology, Nijmegen, The Netherlands
| | - Marc Thelen
- Radboud University Medical Centre, Department of Laboratory Medicine, Nijmegen, The Netherlands.,Amphia Hospital, Department of Laboratory for Clinical Chemistry, part of Result Laboratorium, Breda, The Netherlands.,SKML, Organisation for Quality Assurance of Medical Laboratory Diagnostics, Radboud University, Nijmegen, The Netherlands
| | - Jack F Wetzels
- Radboud University Medical Centre, Radboud Institute for Health Sciences, Department of Nephrology, Nijmegen, The Netherlands
| | - Miranda van Berkel
- Radboud University Medical Centre, Department of Laboratory Medicine, Nijmegen, The Netherlands
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Fan HX, Gou BD, Gao YX, Wu G, Liu SH, Li F, Zhang TL. Protein-bound calcium phosphate in uremic rat serum: a quantitative study. J Biol Inorg Chem 2020; 25:1051-1063. [PMID: 32839886 DOI: 10.1007/s00775-020-01807-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Accepted: 08/04/2020] [Indexed: 10/23/2022]
Abstract
Protein-bound calcium (prCa) constitutes about 40% of serum total calcium, in which albumin is the most dominant protein. Given the chemical interaction between calcium and phosphate (Pi), the increased serum Pi in chronic kidney disease may cause changes in the composition and structure of the prCa fraction. Here, we report the phosphate binding on the protein-bound calcium in uremic rat serum. Using adenine-fed rats as a uremic model, we separated the calcium and phosphate fractions in rat serum by ultrafiltration, and found that the level of protein-bound phosphate (prPi) in the uremic serum was markedly higher than in control. The elevated prPi level was comparable to the prCa level, consistent with the presence of protein-bound calcium phosphate pr(Ca)j-m(CaPi)m. We then confirmed its presence by ex vivo X-ray absorption near-edge structure spectroscopy, revealing the discrete state of the calcium phosphate clusters associated with protein. Finally, in a quantitative investigation using Ca- and Pi-boosted serum, we discovered the threshold concentration for the Pi binding on prCa, and determined the binding constant. The threshold, while preventing Pi from binding to prCa in normal condition, allows the reaction to take place in hyperphosphatemia conditions. The protein-bound calcium phosphate could act as a link between the metabolism of serum proteins and the homeostasis of phosphate and calcium, and it deserves further investigation whether the molar ratio of (prPi/prCa)⋅100% may serve as a serum index of the vascular calcification status in chronic kidney disease.
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Affiliation(s)
- Hong-Xing Fan
- Department of Preclinical and Forensic Medicine, Baotou Medical College, Inner Mongolia University of Science & Technology, Baotou, 014010, People's Republic of China.,CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, 19B Yuquan Road, Beijing, 100049, People's Republic of China
| | - Bao-Di Gou
- Department of Chemical Biology, Peking University School of Pharmaceutical Sciences, 38 Xueyuan Road, Beijing, 100191, People's Republic of China
| | - Yu-Xi Gao
- CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, 19B Yuquan Road, Beijing, 100049, People's Republic of China
| | - Gang Wu
- Department of Preclinical and Forensic Medicine, Baotou Medical College, Inner Mongolia University of Science & Technology, Baotou, 014010, People's Republic of China.
| | - Shu-Hu Liu
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, 19B Yuquan Road, Beijing, 100049, People's Republic of China
| | - Fan Li
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, 19B Yuquan Road, Beijing, 100049, People's Republic of China
| | - Tian-Lan Zhang
- Department of Chemical Biology, Peking University School of Pharmaceutical Sciences, 38 Xueyuan Road, Beijing, 100191, People's Republic of China.
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Lopresti AL. The Effects of Psychological and Environmental Stress on Micronutrient Concentrations in the Body: A Review of the Evidence. Adv Nutr 2020; 11:103-112. [PMID: 31504084 PMCID: PMC7442351 DOI: 10.1093/advances/nmz082] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 06/14/2019] [Accepted: 07/08/2019] [Indexed: 12/21/2022] Open
Abstract
Stress is the nonspecific response of the body to any demand for change. Excess or chronic psychological or environmental stress is associated with an increased risk of mental and physical diseases, with several mechanisms theorized to be associated with its detrimental effects. One underappreciated potential mechanism relates to the effects of psychological and environmental stress on micronutrient concentrations. Micronutrients (vitamins and minerals) are essential for optimal physical and mental function, with deficiencies associated with an array of diseases. In this article, animal and human studies investigating the effects of various psychological and environmental stressors on micronutrient concentrations are reviewed. In particular, the effects of psychological stress, sleep deprivation, and physical exercise on micronutrient concentrations and micronutrient excretion are summarized. Micronutrients identified in this review include magnesium, zinc, calcium, iron, and niacin. Overall, the bulk of evidence suggests stress can affect micronutrient concentrations, often leading to micronutrient depletion. However, before definitive conclusions about the effects of stress can be made, the impact of different stressors, stress severity, and acute versus chronic stress on micronutrient concentrations requires investigation. Moreover, the impact of stress on micronutrients in different populations varying in age, gender, and premorbid health status and the durability of changes after a stressor is resolved require examination. The medical, physical, and psychological implications of nutrient changes caused by a stressor also remain to be determined.
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Affiliation(s)
- Adrian L Lopresti
- School of Psychology and Exercise Science, Murdoch University, Perth, Australia; and Clinical Research Australia, Duncraig, Australia,Address correspondence to ALL (e-mail: )
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de Roij van Zuijdewijn CL, de Haseth DE, van Dam B, Bax WA, Grooteman MP, Bots ML, Blankestijn PJ, Nubé MJ, van den Dorpel MA, ter Wee PM, Penne EL. Role of Albumin Assay on Calcium Levels and Prescription of Phosphate Binders in Chronic Hemodialysis Patients. Nephron Clin Pract 2018; 140:211-217. [PMID: 30212837 PMCID: PMC6262677 DOI: 10.1159/000492238] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 07/17/2018] [Accepted: 07/17/2018] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND/AIMS In hemodialysis (HD) patients, the bromcresol green (BCG) assay overestimates, whereas the bromcresol purple (BCP) assay underestimates albumin concentration. Since corrected calcium concentrations depend on albumin, the albumin assay may have implications for the management of bone mineral disorders. METHODS A subset of patients from CONTRAST, a cohort of prevalent HD patients, was analyzed. Bone mineral parameters and prescription of medication were compared between patients in whom albumin was assessed by BCP versus BCG. RESULTS Albumin was assessed by BCP in 331 patients (9 of 25 centers) and by BCG in 175 patients (16 of 25 centers). Albumin was the lowest in the BCP group (34.5 ± 4.2 vs. 40.3 ± 3.1 g/L; p < 0.0005). Measured calcium levels and the prescription of calcium-based phosphate binders were similar in both groups. Corrected calcium levels, however, were markedly higher in the BCP group (2.45 ± 0.18 vs. 2.33 ± 0.18 mmol/L; p < 0.0005). CONCLUSION These findings suggest that calcium levels are not corrected for albumin in clinical practice when considering the prescription of calcium-free or calcium-based phosphate-binders in dialysis patients.
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Affiliation(s)
| | - Dinky E. de Haseth
- Department of Internal Medicine, Northwest Clinics, Alkmaar, The Netherlands
| | - Bastiaan van Dam
- Department of Internal Medicine, Northwest Clinics, Alkmaar, The Netherlands
| | - Willem A. Bax
- Department of Internal Medicine, Northwest Clinics, Alkmaar, The Netherlands
| | - Muriel P.C. Grooteman
- Amsterdam UMC, Vrije Universiteit Amsterdam, Department of Nephrology, Amsterdam Cardiovascular Sciences, Amsterdam, The Netherlands
| | - Michiel L. Bots
- Julius Center for Health Sciences and Primary Care, University Medical Center, Utrecht University, Utrecht, The Netherlands
| | - Peter J. Blankestijn
- Department of Nephrology and Hypertension, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Menso J. Nubé
- Amsterdam UMC, Vrije Universiteit Amsterdam, Department of Nephrology, Amsterdam Cardiovascular Sciences, Amsterdam, The Netherlands
| | | | - Pieter M. ter Wee
- Amsterdam UMC, Vrije Universiteit Amsterdam, Department of Nephrology, Amsterdam Cardiovascular Sciences, Amsterdam, The Netherlands
| | - Erik L. Penne
- Department of Internal Medicine, Northwest Clinics, Alkmaar, The Netherlands
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Lian IA, Åsberg A. Should total calcium be adjusted for albumin? A retrospective observational study of laboratory data from central Norway. BMJ Open 2018; 8:e017703. [PMID: 29627804 PMCID: PMC5892769 DOI: 10.1136/bmjopen-2017-017703] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
OBJECTIVES Albumin-adjusted total calcium is often used as a surrogate marker for free calcium to evaluate hypocalcaemia or hypercalcaemia. Many adjustment formulas based on simple linear regression models have been published, and continue to be used in spite of questionable diagnostic accuracy. In the hope of finding a more pure albumin effect on total calcium, we used multiple linear regression models to adjust for other relevant variables. The regression coefficients of albumin were used to construct local adjustment formulas, and we tested whether the diagnostic accuracy was improved compared with previously published formulas and unadjusted calcium. DESIGN A retrospective hospital laboratory data study. DATA SOURCES The local hospital laboratory data system. SETTING Norway, 2006-2015. PARTICIPANTS 6549 patients above 2 years of age, where free calcium standardised at pH 7.40, total calcium, creatinine, albumin and phosphate had been analysed in a single blood draw, including hospitalised patients and patients from outpatient clinics and general practice. MAIN OUTCOME MEASURES Diagnostic accuracy by Harrell's c and receiver operating characteristic curve analysis, using free calcium standardised at pH 7.40 as a gold standard, in subgroups with estimated glomerular filtration rate (eGFR) ≥60 or <60 mL/min/1.73 m2. RESULTS In the subgroup with eGFR <60 mL/min/1.73 m2, the Harrell's c of unadjusted total calcium (0.801) was significantly larger than those of the local formulas (0.790, p=0.002) and the best formula taken from literature (0.791, p=0.004). In the subgroup with eGFR ≥60 mL/min/1.73 m2, no significant differences were found between these three formulas. CONCLUSIONS Our study shows that the diagnostic accuracy of unadjusted total calcium is superior to several commonly used adjustment formulas, and we suggest that the use of such formulas should be abandoned in clinical practice. If the clinician does not trust total calcium to reflect the calcium status of the patient, free calcium should be measured.
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Affiliation(s)
- Ingrid Alsos Lian
- Department of Clinical Chemistry, St.Olavs hospital, Trondheim, Norway
| | - Arne Åsberg
- Department of Clinical Chemistry, St.Olavs hospital, Trondheim, Norway
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Ridefelt P, Helmersson-Karlqvist J. Albumin adjustment of total calcium does not improve the estimation of calcium status. Scand J Clin Lab Invest 2017; 77:442-447. [PMID: 28613958 DOI: 10.1080/00365513.2017.1336568] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
BACKGROUND There is a longstanding controversy as to whether plasma measurements of total calcium should be adjusted for albumin concentration, and if so which formulas are the most appropriate. METHODS Ionised calcium, total calcium and albumin results, analysed at the same time at Uppsala University Hospital Laboratory between February 2005 and June 2013, were retrieved from a laboratory information system. The dataset included results from 20,003 patients. Total calcium was albumin-modified by a locally derived formula, based on 3106 patients from the dataset, and formulas from the literature. The agreement between the reference method ionised calcium and unadjusted total calcium and the seven different albumin-modifying calcium formulas, respectively, were compared with intra-class correlation coefficients (ICC). RESULTS Total calcium showed substantial agreement to ionised calcium, ICC 0.85 (95% CI 0.84-0.86) for the whole validation cohort. Albumin-modified calcium by different formulas showed significantly less or equal agreement, however the locally determined formula performed better than formulas taken from the literature. Also, total calcium classified the patient as hypo-normo- or hypercalcemic right in 82% of the patients. The albumin-modified calcium did not classify patients significantly better except in the subgroup hypoalbuminemia (<30 g/L) where the local formula classified the patients slightly better than total calcium. CONCLUSIONS Albumin modification of total calcium determinations is unlikely to add valuable information, and this practice should be abandoned. Ionised calcium should be used more frequently when aberrant results for total calcium are followed up, or in patients with known hypoalbuminemia.
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Affiliation(s)
- Peter Ridefelt
- a Department of Medical Sciences , Clinical Chemistry, Uppsala University , Uppsala , Sweden
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11
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Guiducci L, Maffei S, Sabatino L, Zyw L, Battaglia D, Vannucci A, Di Cecco P, Vassalle C. Significance of the ionized calcium measurement to assess calcium status in osteopenic/osteoporosis postmenopausal outpatients. Gynecol Endocrinol 2017; 33:383-388. [PMID: 28102095 DOI: 10.1080/09513590.2016.1270932] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
INTRODUCTION Evaluation of calcium status is important in the osteoporotic risk assessment. Although guidelines indicate total calcium (tCa) as first-line measurement, directly measured ionized calcium (m-iCa), considered as the gold standard, is more and more often required. Aim of this study is to evaluate the agreement between m-iCa, tCa and iCa calculated from a formula based on total calcium and albumin (c-iCa) in osteopenic/osteoporotic postmenopausal outpatients. METHODS A total of 140 postmenopausal outpatients, 41 osteopenic (OPN) and 99 osteoporotic (OP) were enrolled. Levels of tCa, m-iCa, c-iCa, total protein and albumin, vitamin D (25-OHD), parathyroid hormone 1-84 (PTH), bone alkaline phosphatase, osteocalcin and serum collagen type 1 cross-linked C-telopeptide (CTX) were also measured. RESULTS There were no statistically significant differences between OPN and OP groups regarding values of tCa, m-iCa, and c-iCa, 25-OHD and PTH. However, OP women had lower levels of CTX (p < 0.05). A significant direct correlation between m-iCa and tCa (r = 0.60, p < 0.001) and c-iCa (r = 0.61, p < 0.001) was found. Women with isolated hyper-m-iCa had similar DEXA parameter levels respect to the other patients. However, one patient with confirmed primary hyperparathyroidism presented hyper-m-iCa versus normal tCa and c-iCa values. CONCLUSIONS The use of tCa could be sufficient to characterize the calcium status in postmenopausal outpatients, but reflexive calcium testing strategy for m-iCa test is necessary to women presenting the low or high extremes of tCa levels, or in women with suspected PHPT.
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Affiliation(s)
- Letizia Guiducci
- a Institute of Clinical Physiology, CNR National Research Council , Pisa , Italy and
| | - Silvia Maffei
- b Fondazione CNR-Regione Toscana G Monasterio , Pisa , Italy
| | - Laura Sabatino
- a Institute of Clinical Physiology, CNR National Research Council , Pisa , Italy and
| | - Luc Zyw
- b Fondazione CNR-Regione Toscana G Monasterio , Pisa , Italy
| | | | | | - Pietro Di Cecco
- b Fondazione CNR-Regione Toscana G Monasterio , Pisa , Italy
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Obi Y, Nguyen DV, Streja E, Rivara MB, Rhee CM, Lau WL, Chen Y, Kovesdy CP, Mehrotra R, Kalantar-Zadeh K. Development and Validation of a Novel Laboratory-Specific Correction Equation for Total Serum Calcium and Its Association With Mortality Among Hemodialysis Patients. J Bone Miner Res 2017; 32:549-559. [PMID: 27714897 PMCID: PMC5947953 DOI: 10.1002/jbmr.3013] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Revised: 09/23/2016] [Accepted: 10/05/2016] [Indexed: 12/23/2022]
Abstract
Conventional albumin-corrected calcium is inaccurate in predicting ionized calcium, and hidden hypercalcemia, characterized as high ionized calcium with normal total calcium, is associated with higher mortality in hemodialysis patients. By using a national cohort of hemodialysis patients in the Unites States, a novel laboratory-specific prediction equation composed of total calcium, albumin, and phosphorus was derived from 242 patients in the South Atlantic division (adjusted R2 = 0.80 versus 0.71 for the conventional equation) and then validated among 566 patients in the other divisions (adjusted R2 = 0.79 versus 0.68 for the conventional equation). Compared with the conventional equation, the novel equation showed a greater correlation with intact parathyroid hormone. Its relative performance against the conventional equation was consistent across subgroups based on medications related to calcium metabolism. The novel equation also had a higher sensitivity (57% versus 34%) and an equivalent specificity (99% versus 100%) against ionized hypercalcemia at a cut-off value of 10.2 mg/dL. Sensitivity and specificity at 9.4 mg/dL was 94% and 76% (versus 87% and 82% for the conventional equation), respectively. A survival analysis in 87,779 incident hemodialysis patients showed that among patients who were categorized as having a high-normal calcium status (ie, >9.4 to 10.2 mg/dL) by the conventional equation, there appeared a trend toward higher adjusted mortality risk across higher calcium status defined according to the novel equation. Meanwhile, the mortality risk was consistent across calcium strata defined according to the conventional equation within the categories defined by the novel equation. In conclusion, in comparison to the conventional equation, a novel laboratory-specific correction equation derived for correction of total calcium performs significantly better in ascertaining hidden hypercalcemia in hemodialysis patients, and aids in identifying patients at higher risk for mortality. © 2016 American Society for Bone and Mineral Research.
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Affiliation(s)
- Yoshitsugu Obi
- Harold Simmons Center for Kidney Disease Research and Epidemiology, Division of Nephrology and Hypertension, University of California Irvine, School of Medicine, Orange, CA, USA
| | - Danh V Nguyen
- Biostatistics, Epidemiology, and Research Design Unit, Institute for Clinical and Translational Science, University of California Irvine, Orange, CA, USA
- Department of Medicine, University of California Irvine, School of Medicine, Orange, CA, USA
| | - Elani Streja
- Harold Simmons Center for Kidney Disease Research and Epidemiology, Division of Nephrology and Hypertension, University of California Irvine, School of Medicine, Orange, CA, USA
| | - Matthew B Rivara
- Kidney Research Institute and Harborview Medical Center, Division of Nephrology, University of Washington, Seattle, WA, USA
| | - Connie M Rhee
- Harold Simmons Center for Kidney Disease Research and Epidemiology, Division of Nephrology and Hypertension, University of California Irvine, School of Medicine, Orange, CA, USA
| | - Wei Ling Lau
- Harold Simmons Center for Kidney Disease Research and Epidemiology, Division of Nephrology and Hypertension, University of California Irvine, School of Medicine, Orange, CA, USA
| | - Yanjun Chen
- Biostatistics, Epidemiology, and Research Design Unit, Institute for Clinical and Translational Science, University of California Irvine, Orange, CA, USA
| | - Csaba P Kovesdy
- Division of Nephrology, University of Tennessee Health Science Center, Memphis, TN, USA
- Nephrology Section, Memphis VA Medical Center, Memphis, TN, USA
| | - Rajnish Mehrotra
- Kidney Research Institute and Harborview Medical Center, Division of Nephrology, University of Washington, Seattle, WA, USA
| | - Kamyar Kalantar-Zadeh
- Harold Simmons Center for Kidney Disease Research and Epidemiology, Division of Nephrology and Hypertension, University of California Irvine, School of Medicine, Orange, CA, USA
- Fielding School of Public Health at UCLA, Los Angeles, CA, USA
- Los Angeles Biomedical Research Institute at Harbor-UCLA, Torrance, CA, USA
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Jean G, Granjon S, Zaoui E, Deleaval P, Hurot JM, Lorriaux C, Mayor B, Chazot C. Usefulness and feasibility of measuring ionized calcium in haemodialysis patients. Clin Kidney J 2015; 8:378-87. [PMID: 26251703 PMCID: PMC4515894 DOI: 10.1093/ckj/sfv039] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 05/04/2015] [Indexed: 12/21/2022] Open
Abstract
Background Measuring blood calcium level is recommended in haemodialysis (HD) patients. The Kidney Disease Improving Global Outcomes position states that the measurement of ionized calcium (ICa) level is preferred, but in the clinical setting, due to technical difficulties, total calcium (tCa) level is preferred to ICa. Aim The aim of this study was to test the possibility of delayed ICa analysis using frozen serum, and so to identify the factors associated with predialysis ICa level and compare the ability of tCa and Alb-Ca to predict ICa level and finally to compare the survival rate according to the three calcium measurements. Methods All prevalent HD patients, dialysed by a native AV fistula in a 3 × 4 to 3 × 8 h schedule, had their predialysis ICa, tCa and Alb-Ca levels and usual mid-week biology recorded. Intergroup comparisons between ICa quartile were performed. Bland–Altman plots and linear regression were used to assess the differences between 30 fresh and frozen samples. Survival analyses were performed using ICa and tCa levels. Results Comparing fresh blood and frozen serum samples, linear regression (y = 0.98 + 0.02, r = 0.961) showed that the two methods were quite identical with the same mean ICa value (1.1 ± 0.1 mmol/L, P = 0.45). A total of 160 HD patients were included in the study. Hypocalcaemia, using ICa values, was highly prevalent in our population (40%) whereas hypercalcaemia was observed only in three cases (1.8%). In predicting ICa hypocalcaemia (<1.12 mmol/L, n = 64), the use of tCa was accurate in 48.4% of patients, and the use of Alb-Ca was accurate in only 17.2% of patients; tCa was not a predictive factor for hypercalcaemia (ICa > 1.32 mmol/L, n = 3); Alb-Ca value predicted hypercalcaemia in 2/3 of the patients. In predicting normocalcaemia, the use of tCa values was correct in 92.4% of patients and the use of Alb-Ca values in 88.1% of patients; only younger age (P = 0.03) and female sex (P = 0.01) were associated with higher ICa quartile. None of the three calcium measures was significantly associated with survival rate using log-rank and Cox models adjusted for age, dialysis vintage, diabetes and sex. Conclusion In the present study, we report that (1) delayed ICa measure is feasible in dialysis patients using a freezing technique, (2) hypocalcaemia is highly prevalent in HD patients and poorly predicted by Alb-Ca level, (3) the main factor associated with ICa level is sex of the individual and (4) calcaemia is not associated with survival rate using any of the three methods.
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Affiliation(s)
- Guillaume Jean
- Dialysis, NephroCare Tassin-Charcot, Sainte Foy-Les-Lyon, France
| | - Samuel Granjon
- Biochemistry Department, Laboratoire Novescia, Sainte Foy Les Lyon, Rhone Alpes, France
| | - Eric Zaoui
- Biochemistry Department, Laboratoire Novescia, Sainte Foy Les Lyon, Rhone Alpes, France
| | - Patrik Deleaval
- Dialysis, NephroCare Tassin-Charcot, Sainte Foy-Les-Lyon, France
| | - Jean-Marc Hurot
- Dialysis, NephroCare Tassin-Charcot, Sainte Foy-Les-Lyon, France
| | | | - Brice Mayor
- Dialysis, NephroCare Tassin-Charcot, Sainte Foy-Les-Lyon, France
| | - Charles Chazot
- Dialysis, NephroCare Tassin-Charcot, Sainte Foy-Les-Lyon, France
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Abstract
Calcium is essential for both neurotransmitter release and muscle contraction. Given these important physiological processes, it seems reasonable to assume that hypocalcemia may lead to reduced neuromuscular excitability. Counterintuitively, however, clinical observation has frequently documented hypocalcemia’s role in induction of seizures and general excitability processes such as tetany, Chvostek’s sign, and bronchospasm. The mechanism of this calcium paradox remains elusive, and very few pathophysiological studies have addressed this conundrum. Nevertheless, several studies primarily addressing other biophysical issues have provided some clues. In this review, we analyze the data of these studies and propose an integrative model to explain this hypocalcemic paradox.
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Affiliation(s)
- Pengcheng Han
- Barrow Neurological Institute, Dignity Health St Joseph's Hospital and Medical Center and Medical Center, Phoenix, AZ, USA
| | - Bradley J Trinidad
- Creighton University School of Medicine-Phoenix Campus, Phoenix, AZ, USA
| | - Jiong Shi
- Barrow Neurological Institute, Dignity Health St Joseph's Hospital and Medical Center and Medical Center, Phoenix, AZ, USA
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15
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Rivara MB, Ravel V, Kalantar-Zadeh K, Streja E, Lau WL, Nissenson AR, Kestenbaum B, de Boer IH, Himmelfarb J, Mehrotra R. Uncorrected and Albumin-Corrected Calcium, Phosphorus, and Mortality in Patients Undergoing Maintenance Dialysis. J Am Soc Nephrol 2015; 26:1671-81. [PMID: 25613037 DOI: 10.1681/asn.2014050472] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Accepted: 09/02/2014] [Indexed: 12/20/2022] Open
Abstract
Uncorrected serum calcium concentration is the first mineral metabolism metric planned for use as a quality measure in the United States ESRD population. Few studies in patients undergoing either peritoneal dialysis (PD) or hemodialysis (HD) have assessed the association of uncorrected serum calcium concentration with clinical outcomes. We obtained data from 129,076 patients on dialysis (PD, 10,066; HD, 119,010) treated in DaVita, Inc. facilities between July 1, 2001, and June 30, 2006. After adjustment for potential confounders, uncorrected serum calcium <8.5 and ≥10.2 mg/dl were associated with excess mortality in patients on PD or HD (comparison group uncorrected calcium 9.0 to <9.5 mg/dl). Additional adjustment for serum albumin concentration substantially attenuated the all-cause mortality hazard ratios (HRs) associated with uncorrected calcium <8.5 mg/dl (HR, 1.29; 95% confidence interval [95% CI], 1.16 to 1.44 for PD; HR, 1.17; 95% CI, 1.13 to 1.20 for HD) and amplified the HRs associated with calcium ≥10.2 mg/dl (HR, 1.65; 95% CI, 1.42 to 1.91 for PD; HR, 1.59; 95% CI, 1.53 to 1.65 for HD). Albumin-corrected calcium ≥10.2 mg/dl and serum phosphorus ≥6.4 mg/dl were also associated with increased risk for death, irrespective of dialysis modality. In summary, in a large nationally representative cohort of patients on dialysis, abnormalities in markers of mineral metabolism, particularly high concentrations of serum calcium and phosphorus, were associated with increased mortality risk. Additional studies are needed to investigate whether control of hypercalcemia and hyperphosphatemia in patients undergoing dialysis results in improved clinical outcomes.
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Affiliation(s)
- Matthew B Rivara
- Kidney Research Institute, University of Washington, Seattle, Washington;
| | - Vanessa Ravel
- Harold Simmons Center for Chronic Disease Research and Epidemiology, University of California Irvine Medical Center, Irvine, California
| | - Kamyar Kalantar-Zadeh
- Harold Simmons Center for Chronic Disease Research and Epidemiology, University of California Irvine Medical Center, Irvine, California; Division of Nephrology and Hypertension, University of California Irvine Medical Center, Orange, California
| | - Elani Streja
- Harold Simmons Center for Chronic Disease Research and Epidemiology, University of California Irvine Medical Center, Irvine, California; Fielding School of Public Health, University of California Los Angeles, Los Angeles, California
| | - Wei Ling Lau
- Division of Nephrology and Hypertension, University of California Irvine Medical Center, Orange, California
| | - Allen R Nissenson
- Division of Nephrology, Department of Medicine, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, California; and DaVita, Inc., El Segundo, California
| | - Bryan Kestenbaum
- Kidney Research Institute, University of Washington, Seattle, Washington
| | - Ian H de Boer
- Kidney Research Institute, University of Washington, Seattle, Washington
| | | | - Rajnish Mehrotra
- Kidney Research Institute, University of Washington, Seattle, Washington
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Gonzalez-Parra E, Gonzalez-Casaus ML, Arenas MD, Sainz-Prestel V, Gonzalez-Espinoza L, Muñoz-Rodriguez MA, Tabikh A, Egido J, Ortiz A. Individualization of dialysate calcium concentration according to baseline pre-dialysis serum calcium. Blood Purif 2014; 38:224-33. [PMID: 25531119 DOI: 10.1159/000366126] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Accepted: 07/22/2014] [Indexed: 11/19/2022]
Abstract
BACKGROUND A positive calcium balance may contribute to vascular calcification, while a negative balance increases iPTH. We explored the impact of different dialysate calcium concentrations on bone and mineral metabolism parameters according to pre-dialysis serum calcium levels. RESULTS Fifty-six hemodialysis patients were dialyzed with 3.0 or 2.5 mEq/l dialysate [calcium] in a crossover study of two weeks. Bone mineral metabolites were measured prior to and following the hemodialysis session. A 3.0 mEq/l dialysate [calcium] increased more post-dialysis total calcium and ionized calcium than 2.5 mEq/l dialysate [calcium]. The mildest dialysis-induced changes in calcium and PTH were observed in patients with pre-dialysis serum calcium <8.75 mg/dl dialyzed with 2.5 mEq/l dialysate [calcium] and in patients with pre-dialysis serum calcium >9.15 mg/dl dialyzed with 3.0 mEq/l calcium dialysate. CONCLUSION In conclusion, the individualization of dialysate calcium concentration according to baseline pre-dialysis serum calcium may prevent major excursions in post-dialysis serum calcium and iPTH levels. SHORT SUMMARY High calcium dialysate may increase serum calcium in hemodialysis patients, while low dialysate calcium may increase PTH. Individualization of dialysate calcium according to predialysis serum calcium levels may prevent or decrease unwanted excursions of both serum calcium and PTH.
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17
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Ferreira-Junior M, Lichtenstein A, Sales MM, Taniguchi LU, Aguiar FJBD, Fonseca LAM, Sumita NM, Duarte AJDS. Rational use of blood calcium determinations. SAO PAULO MED J 2014; 132:243-8. [PMID: 25055071 PMCID: PMC10496734 DOI: 10.1590/1516-3180.2014.1324731] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2013] [Revised: 11/28/2013] [Accepted: 11/29/2013] [Indexed: 11/22/2022] Open
Abstract
CONTEXT AND OBJECTIVE This study was motivated by the recent excessive increase in requests for blood calcium determinations and laboratory tests in general, in the Hospital das Clínicas complex of Faculdade de Medicina, Universidade de São Paulo (HCFMUSP). Its aim was to suggest rules for the determination of total and ionized calcium in our intensive care units, emergency department, wards and outpatient services, thus contributing towards improving the quality of medical care and achieving more appropriate use of human and financial resources. DESIGN AND SETTING Critical analysis on clinical and laboratory data and the pertinent scientific literature, conducted by the study group for rational clinical laboratory use, which is part of the Central Laboratory Division, HCFMUSP. METHODS The study group reviewed scientific publications, statistics and clinical and laboratory data concerning requests for total and ionized calcium determinations in the settings of intensive care units, emergency department, wards and outpatient services. RESULTS From this critical analysis, clinical decision flow diagrams aimed at providing guidance for ordering these tests were constructed. CONCLUSIONS Use of the proposed flow diagrams may help to limit the numbers of inappropriate requests for ionized and total calcium determinations, with consequent reductions in the number of tests, risks to patients and unnecessary costs.
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Affiliation(s)
- Mario Ferreira-Junior
- Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brazil
| | - Arnaldo Lichtenstein
- Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brazil
| | - Maria Mirtes Sales
- Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brazil
| | | | | | | | - Nairo Massakazu Sumita
- Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brazil
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18
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Golzy M, Bessette RW, Carter RL. Renal function, calcium regulation, and time to hospitalization of patients with chronic kidney disease. BMC Nephrol 2013; 14:154. [PMID: 23865435 PMCID: PMC3723874 DOI: 10.1186/1471-2369-14-154] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2012] [Accepted: 07/15/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Chronic kidney disease is associated with disruption of the endocrine system that distorts the balance between calcitriol, calcium, phosphate and parathyroid hormone in the calcium regulation system. This can lead to calcification of the arterial tree and increased risk of cardiovascular disease and death. In this study we develop a health metric, based on biomarkers involved in the calcium regulation system, for use in identifying patients at high risk for future high-cost complications. METHODS This study is a retrospective observational study involving a secondary analysis of data from the kidney disease registry of a regional managed care organization. Chronic kidney disease patients in the registry from November 2007 through November 2011 with a complete set of observations of estimated glomerular filtration rate, calcitriol, albumin, free calcium, phosphate, and parathyroid hormone were included in the study (n = 284). Weibull regression model was used to identify the most significant lab tests in predicting "waiting time to hospitalization". A multivariate linear path model was then constructed to investigate direct and indirect effects of the biomarkers on this outcome. RESULTS The results showed negative significant direct effects of phosphate and parathyroid hormone on "waiting time to hospitalization". Base on this result, the risk of hospitalization increases 16.8% for each 0.55 mg/dl increase in phosphate level and 13.5% for each 0.467 increase in the natural logarithm of parathyroid hormone. Positive indirect effects of calcitriol surrogate (calcidiol), free calcium, albumin and estimated glomerular filtration rate were observed but were relatively small in magnitude. CONCLUSION Variables involved in the calcium regulation system should be included in future efforts to develop a quality of care index for Chronic Kidney disease patients.
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Affiliation(s)
- Mojgan Golzy
- Department of Biostatistics and Population Health Observatory, State University of New York at Buffalo, Buffalo, NY 14214-3000, USA
| | - Russell W Bessette
- Abell Administration Center, University of Louisville, 323 East Chestnut St., Louisville, Kentucky 40202, USA
| | - Randy L Carter
- Department of Biostatistics and Population Health Observatory, State University of New York at Buffalo, Buffalo, NY 14214-3000, USA
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20
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Endres DB. Investigation of hypercalcemia. Clin Biochem 2012; 45:954-63. [DOI: 10.1016/j.clinbiochem.2012.04.025] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2012] [Revised: 04/19/2012] [Accepted: 04/26/2012] [Indexed: 02/06/2023]
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21
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Different manufacturers of syringes: A new source of variability in blood gas, acid–base balance and related laboratory test? Clin Biochem 2012; 45:683-7. [DOI: 10.1016/j.clinbiochem.2012.03.007] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Revised: 03/03/2012] [Accepted: 03/05/2012] [Indexed: 11/20/2022]
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Ionized calcium. Clin Chim Acta 2011; 412:696-701. [DOI: 10.1016/j.cca.2011.01.004] [Citation(s) in RCA: 121] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2010] [Revised: 01/04/2011] [Accepted: 01/04/2011] [Indexed: 11/23/2022]
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