scholarly journals Determination of Reference Intervals for Serum Total Calcium in the Vitamin D-Replete Pediatric Population

2013 ◽  
Vol 98 (12) ◽  
pp. E1946-E1950 ◽  
Author(s):  
Jeffrey D. Roizen ◽  
Vipul Shah ◽  
Michael A. Levine ◽  
Dean C. Carlow
Keyword(s):  
Vitamin D ◽  
Pediatric Population ◽  
Reference Intervals ◽  
Total Calcium ◽  
Serum Total Calcium

scholarly journals Analytical methods and performance of the immunoassay methods for determination of vitamin d in comparison to mass spectrometry / Analitičke metode i izvođenje imunometrijskih određivanja vitamina d u poređenju sa masenom spektrometrijom

2012 ◽  
Vol 31 (4) ◽  
pp. 333-338 ◽  
Author(s):  
Nikolina Babić
Keyword(s):  
Mass Spectrometry ◽  
Vitamin D ◽  
Transition Period ◽  
Medical Center ◽  
Pediatric Population ◽  
Well Being ◽  
Technical Expertise ◽  
Assay Sensitivity ◽  
Clinical Laboratories

Summary Demand for vitamin D testing has been on a constant rise worldwide, partially due to mounting evidence linking vitamin D status to overall health and well-being. Currently available assays measure 25-hydroxy vitamin D (25-OHD), a major circulating form of vitamin D. Available methodologies include immunoassays and mass spectrometry based methods (LC-MS/MS). Until recently, the only immunoassays available for diagnostic use in the US have been DiaSorin radioimmunoassay (RIA) and an automated immunoassay on a LIAISON® platform. Within the last year, Siemens and Abbott successfully launched immuno - assays for determination of total vitamin D on their respective automated platforms, Centaur® and ARCHITECT®. Development of robust and precise Vitamin D immunoassays has historically been plagued with difficulty. One of the major challenges is development of specific antibodies against such a small antigen. Vitamin D is also highly hy - drophobic molecule predominantly bound to vitamin D binding protein (DBP). It is likely, therefore, that immuno - assays might be affected to varying extent by the DBP concentration. Adoption of LC-MS/MS into clinical laboratories has enabled development of accurate and almost fully automated methods that could handle increasing volume demands, especially in large volume reference laboratories. Smaller to mid-size hospital laboratories as well as physician offices have neither funds nor technical expertise to implement LC-MS/MS based testing. Our laboratory at the University of Chicago Medical Center has also seen in - crease in vitamin D volume and currently performs close to 20,000 25-OHD assays per year. We have recently deve - loped an LC-MS/MS method for quantitation of 25-OHD2 (obtained from plant sources) and 25-OHD3 (endogenous and animal sources). Prior to acquisition of LC-MS/MS instrument, we performed 25-OHD analysis by RIA. Du - ring the transition period, we encountered several challenges, including the necessity to streamline sample preparation as well as the bias introduced by calibration dif ferences. We chose to match our LC-MS/MS method to the RIA method in order to make this transition transparent to the clinician. Most immunoassays available today are acceptable for clinical use and might be method of choice for smaller laboratories. Larger clinical laboratories and aca demic institutions that possess technical expertise, particularly the ones with large pediatric population where assay sensitivity and specificity may be important, might find LC-MS/MS methodology a more suitable choice.

scholarly journals Seizures in patients with idiopathic hypoparathyroidism: effect of antiepileptic drug withdrawal on recurrence of seizures and serum calcium control

2014 ◽  
Vol 170 (5) ◽  
pp. 777-783 ◽  
Author(s):  
Sagar Modi ◽  
Manjari Tripathi ◽  
Soma Saha ◽  
Ravinder Goswami
Keyword(s):  
Vitamin D ◽  
Antiepileptic Drug ◽  
Drug Withdrawal ◽  
Limited Information ◽  
Total Calcium ◽  
Eligibility Criteria ◽  
Serum Total Calcium ◽  
Antiepileptic Drug Withdrawal ◽  
The Mean

ObjectiveThere is limited information on seizures in patients with idiopathic hypoparathyroidism (IH). We assessed seizure characteristics at presentation, subclinical seizures during follow-up, and the effect of antiepileptic drug (AED) withdrawal in IH patients.Designs and methodsSeizure characteristics were assessed in 70 patients with IH attending endocrine clinic. Provoked electroencephalography (EEG) was performed for subclinical seizures in 44 of them. AEDs were withdrawn using strict criteria, i.e. i) no seizure during past 2 years, ii) normal EEG, iii) serum total calcium ≥1.8 mmol/l, and iv) feasibility to follow-up regularly after AED withdrawal for at least 9 months (n=14). The effects of AED withdrawal on seizures and serum total calcium were assessed.ResultsSeizures were present in 64.3% of patients, generalized tonic–clonic in 86.7%, and treated with phenytoin (46.7%), valproate (40%), and carbamazepine (26.7%). Most (69/70) patients were seizure-free during the follow-up of 6.6±4.5 years. Ten of 14 (71.4%) patients were successfully withdrawn from AED and remained seizure free during the follow-up period of 13.5±2.4 months (range 9–18). AEDs were restarted because of the recurrence of seizures (n=3) and poor compliance with calcium/vitamin D (n=1). The mean serum total calcium increased from 1.9±0.19 to 2.1±0.14 mmol/l after AED withdrawal (P=0.004).ConclusionSeizures were present in 64.3% of patients with IH and they responded to AED and calcium/1-α-(OH)D during the follow-up. With strict eligibility criteria, it was possible to withdraw AED in 71% of patients with IH. Serum total calcium improved significantly after AED withdrawal.

scholarly journals Determinação de valores próprios de referência para vitamina D, hormônio paratireoideo e cálcio em um laboratório de análises clínicas

2018 ◽  
Vol 28 (4) ◽  
pp. 28462 ◽  
Author(s):  
Adriana Dalpicolli Rodrigues ◽  
Estefânia Weirich ◽  
Eunice Zanandréa Duarte
Keyword(s):  
Vitamin D ◽  
Direct Method ◽  
Package Insert ◽  
Cross Sectional Study ◽  
Reference Intervals ◽  
Lower Range ◽  
Cross Sectional ◽  
Laboratory Workers ◽  
The Mean

AIMS: To determine the proper reference intervals for vitamin D, parathyroid hormone (PTH) and calcium in a clinical laboratory.METHODS: A retrospective cross-sectional study was carried out at the units of Alfa Ltda. Laboratory, located in Caxias do Sul, in the mountain region of Rio Grande do Sul. The sample included self-declared healthy clients and laboratory workers. The study was based on two research methods (direct and indirect) proposed by the Clinical & Laboratory Standards Institute for the establishment of proper reference intervals for a specific laboratory. The direct method (DM) involved questionnaire application, collection and analysis of blood samples and the indirect method (IM) consisted of database analysis.RESULTS: Results of 241 individuals were evaluated in the DM, of which 120 were female. The mean age of participants was 33.8±10.6 years. IM resulted in 5,485 values for vitamin D, 191 for PTH, and 856 for calcium. The mean age of the individuals was 45.0±15.6 years, 49.0±15.3 years and 48.87±15.41 years, respectively. The proper reference intervals obtained by the DM were statistically equal to those of the IM for the three dosages. When comparing the reference intervals obtained with those available in the manufacturer report, vitamin D resulted in a lower range of normality (report: >30 ng/mL; MD: 10-47 ng/mL; MI: 11-46 ng/mL), PTH in a higher range (report: 15-68.3 ng/mL; MD: 19.2-81.6 ng/mL; MI: 26.1-94.3 ng/mL), and calcium presented very close values (report: 8.3-10.6 ng/mL; MD: 8.3-10.2 ng/mL; MI: 8.2-10.1 ng/mL). There was a statistical difference between the reference intervals established for vitamin D and calcium between genders.CONCLUSIONS: Both MD and MI were efficient for the determination of proper reference intervals. The reference intervals established in the study, specifically for vitamin D and PTH, were different from those suggested in the manufacturer's package insert, which reinforces the recommendation of establishing proper reference intervals for each laboratory.

Potential predictive marker of treatment effectiveness in patients with osteopenic syndrome after surgical menopause

GYNECOLOGY ◽  
2020 ◽  
Vol 22 (4) ◽  
pp. 39-42
Author(s):  
Yansiiat Z. Zaydieva ◽  
Elena V. Kruchinina ◽  
Olga S. Gorenkova ◽  
Elena Yu. Polyakova ◽  
Elena N. Kareva ◽  
...  
Keyword(s):  
Vitamin D ◽  
Combination Therapy ◽  
Vitamin D Receptor ◽  
Surrogate Marker ◽  
Predictive Marker ◽  
Expression Level ◽  
Mineral Density ◽  
Vitamin D Receptors ◽  
Surgical Menopause

Introduction. Patients with surgical menopause have a risk for osteopenic syndrome (OS). Menopausal hormone therapy (MHT) in combination with calcium and vitamin D promotes increase in bone mineral density (BMD). The expression level of vitamin D receptor in mononuclear fraction cells (MNFC) of blood can be considered as a predictive marker of effectiveness of OS therapy. Aim. To search a molecular predictive marker of the effectiveness of OS treatment. Materials and methods. The study included 100 women aged 4055 years with a duration of surgical menopause from 12 months to 6 years. The criterion for including patients in the study was the absence of contraindications to the use of MHT. The subject of the study was the determination of BMD by dual-energy X-ray absorptiometry, polymerase chain reaction diagnostics of the level of expression of vitamin D genes, estradiol and progesterone receptors, determination of 25-OH vitamin D in the blood. Results. Analysis of 12-month OS therapy effectiveness evaluated with a surrogate marker BMD. The increase in BMD up to 34% per year was treated as absence of negative dynamics, more than 4% per year as positive one. Significant effect of combination therapy compared with MHT on BMD in patients with surgical menopause with a low baseline level of BMD (due to hypovitaminosis D) is associated with the anti-inflammatory, bone-protective effect of vitamin D. In both groups of patients not responding; to the prescribed therapy we were able to conduct a comparative analysis of expression level of the target molecules in the MNFC before the start of treatment. The efficacy of MHT and combination therapy for BMD disorders is positively associated with the expression level of vitamin D receptors in MNFC before treatment. Therefore, the vitDR mRNA level is a potential predictive marker of the effectiveness of OS treatment. The expression levels of nuclear estradiol beta receptor and membrane receptor for progesterone in MNFC before treatment showed an upward trend in women responding to therapy. Conclusion. The expression level of the vitamin D receptor in MNFC of blood is significantly lower in the group of women with no/insufficient effect on 12-month combined therapy. This indicator can be considered as a predictive marker of the effectiveness of OS therapy.

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