Assessment of vitamin D status – a changing landscape Herrmann, Markus; Farrell, Christopher-John L.; Pusceddu, Irene ...
Clinical chemistry and laboratory medicine,
01/2017, Letnik:
55, Številka:
1
Journal Article, Web Resource
Recenzirano
Odprti dostop
In recent years it has been shown that vitamin D deficiency is associated with an increased incidence as well as the progression of a broad range of diseases including osteoporosis, rickets, ...cardiovascular disease, autoimmune disease, multiple sclerosis and cancer. Consequently, requests for the assessment of vitamin D status have increased dramatically. Despite significant progress in the analysis of vitamin D metabolites and an expansion of our pathophysiological knowledge of vitamin D, the assessment of vitamin D status remains a challenging and partially unresolved issue. Current guidelines from scientific bodies recommend the measurement of 25-hydroxy vitamin D (25-OHD) in blood as the preferred test. However, growing evidence indicates significant limitations of this test, including analytical aspects and interpretation of results. In addition, the relationships between 25-OHD and various clinical indices, such as bone mineral density and fracture risk, are rather weak and not consistent across races. Recent studies have systematically investigated new markers of vitamin D status including the vitamin D metabolite ratio (VMR) (ratio between 25-OHD and 24,25-dihydroxy vitamin D), bioavailable 25-OHD 25-OHD not bound to vitamin D binding protein (DBP), and free 25-OHD circulating 25-OHD bound to neither DBP nor albumin (ALB). These parameters may potentially change how we will assess vitamin D status in the future. Although these new biomarkers have expanded our knowledge about vitamin D metabolism, a range of unresolved issues regarding their measurement and the interpretation of results prevent their use in daily practice. It can be expected that some of these issues will be overcome in the near future so that they may be considered for routine use (at least in specialized centers). In addition, genetic studies have revealed several polymorphisms in key proteins of vitamin D metabolism that affect the circulating concentrations of vitamin D metabolites. The affected proteins include DBP, 7-dehydrocholesterol synthase and the vitamin D receptor (VDR). Here we aim to review existing knowledge regarding the biochemistry, physiology and measurement of vitamin D. We will also provide an overview of current and emerging biomarkers for the assessment of vitamin D status, with particular attention methodological aspects and their usefulness in clinical practice.
Background
Galcanezumab has shown efficacy and effectiveness in the treatment of episodic and chronic migraine (CM), however, the population represented in randomized clinical trials (RCTs) differs ...from the population observed in real-world setting. To describe the long-term effectiveness and tolerability of galcanezumab in clinical practice in patients excluded from RCTs.
Methods
Multicenter prospective cohort study of consecutive patients with chronic and high-frequency episodic migraine (HFEM) with prior failure to three or more migraine preventive drugs, treated with galcanezumab and followed up for 12 months.
Results
We enrolled 1055 patients, aged 50 (IQR: 42–58), 82.9% female, 76.4% chronic migraine, 69% with at least one exclusion criteria for RCTs, including age > 65 (
n
= 121), concomitant use of onabotulinumtoxinA (
n
= 185), daily headache at baseline (
n
= 347), chronic painful syndromes (
n
= 206), fibromyalgia (
n
= 101) or treatment resistance (
n
= 957). The median number of prior preventive treatments was 4 (IQR: 3–5). The retention rate was 90.8%, 76.8% and 71.4% at 3, 6 and 12 months. The main reasons for treatment discontinuation were lack of effectiveness (21.1%) and inadequate tolerability (6.6%).
The 30%, 50% and 75% responder rates were 62.6%, 49.8% and 24.2% between weeks 8–12; 60.9%, 48.8% and 24.6% between weeks 20–24; and 59.7%, 48.3% and 24.6% between weeks 44–48. Daily headache at baseline (OR: 0.619; 95%CI: 0.469–0.817) and patient’s age (OR: 1.016; 95%CI: 1.005–1.026) were associated with 50% response at weeks 20–24. The variables that were associated with a higher reduction of headache days between weeks 20–24 were patient’s age (0.068; 95% CI: 0.018–0.119) and headache days per month at baseline (0.451; 95% CI: 0.319–0.583), while psychiatric comorbidity (-1.587; 95% CI: -2.626—0.538) and daily headache at baseline (-2.718; 95% CI: -4.58—0.869) were associated with fewer reduction in the number of headache days between weeks 20–24.
Conclusion
This study provides class III evidence of effectiveness and tolerability of galcanezumab in patients with HFEM and CM with comorbidities that would result in exclusion of the pivotal RCTs. Nonetheless, the clinical results over a 12-month period were similar to the efficacy observed in randomized controlled trials. Few patients discontinued the drug due to inadequate tolerability.
•Intact glucagon can be simply and accurately measured by LC-MS/MS.•Fast and easy sample preparation with solid-phase extraction is suitable to routine application.•The described method can open up ...the possibility to standardize glucagon analysis.
The quantitation of glucagon remains a challenging immunoassay, mainly due to cross-reactivity. A sensitive, rapid and specific intact glucagon method is therefore necessary for quality routine analysis. A tandem mass spectrometry method to fulfill this objective is described in this work.
Glucagon was extracted from plasma employing a mixed-mode anion exchange solid-phase extraction. Sample stability was assessed in K2-EDTA and P800 tubes at different temperatures. We compared our method to two different immunoassays. FDA and EMA guidelines were followed for validation. An external quality control program served for comparison with other laboratories.
Assay imprecision was below 4%. Recoveries were within 95–103%. LoQ was 8.75 pg/mL. Total analytical CV was 2.91%. Samples were found stable at 4 °C for less than 4 h. Diasource® RIA disagreed with our method. Mercodia® ELISA provided a closer agreement, also proven by external quality control samples.
A rapid and specific LC-MS/MS method for glucagon quantitation has been developed, validated and is suitable to routine care. The simplicity and the good performances in terms of time and specificity, could open the possibility to establish a standardized method for glucagon.
Rapid, easy and reliable measurement of the major vitamin D metabolites is required in order to fulfill the needs of a clinical routine laboratory. To overcome these challenges, we have developed and ...validated a LC-MS/MS method for the quantification of 25-hydroxyvitamin D2 and D3, epi-25-hydroxyvitamin D3 and 24,25-dihydroxyvitamin D3.
Sample preparation was based on precipitation and centrifugation of 100μL of patient serum, followed by injection into the LC-MS/MS system. Samples from Vitamin D Standardization Program (n=80) and patient samples (n=281) have been compared with a reference LC-MS/MS method. For the analytical validation NIST and Labquality quality control materials were used.
Mean intra-assay and inter-assay imprecision were <6.0 and 6.4% and mean recoveries were within 95–104%. LOQ's were 0.5μg/L for 24,25(OH)2D3, 1.1μg/L for 25(OH)D3 and epi-25(OH)D3 and 1.7μg/L for 25(OH)D2. A 3% bias obtained between the proposed and the reference method satisfies Vitamin D Standardization Program recommendations.
We present a rapid, easy, reliable and cost-effective method completely adequate for routine testing, which permits the measurement of the ratio of 24,25-dihydroxyvitamin D to 25-hydroxyvitamin D, Vitamin D Metabolite Ratio (VMR), in serum samples.
•Determination of vitamin D metabolites by LC-MS/MS in serum•Fast, easy, reliable and cost-effective method for routine testing•Complete analytical and clinical validation
•We determined NP and 4-t-OP combining isotope dilution mass spectrometry (IDMS) and isotope pattern deconvolution (IPD).•Matrix effect compensation based on IDMS methodology and the minimal labeled ...standard was used which avoids isotopic effects.•In-house synthesis and characterization of the isotope-marked compound 13C1-4-tert-octylphenol.•A hollow-fiber liquid phase microextraction procedure offers a cheap and easy extraction of alkylphenols from water samples.•Full validation of the proposed HF-LPME-UHPLC–MS/MS methodology in wastewater samples.
We present here a new measurement method for the rapid extraction and accurate quantification of technical nonylphenol (NP) and 4-t-octylphenol (OP) in complex matrix water samples by UHPLC-ESI-MS/MS. The extraction of both compounds is achieved in 30min by means of hollow fiber liquid phase microextraction (HF-LPME) using 1-octanol as acceptor phase, which provides an enrichment (preconcentration) factor of 800. On the other hand we have developed a quantification method based on isotope dilution mass spectrometry (IDMS) and singly 13C1-labeled compounds. To this end the minimal labeled 13C1-4-(3,6-dimethyl-3-heptyl)-phenol and 13C1-t-octylphenol isomers were synthesized, which coelute with the natural compounds and allows the compensation of the matrix effect. The quantification was carried out by using isotope pattern deconvolution (IPD), which permits to obtain the concentration of both compounds without the need to build any calibration graph, reducing the total analysis time. The combination of both extraction and determination techniques have allowed to validate for the first time a HF-LPME methodology at the required levels by legislation achieving limits of quantification of 0.1ngmL−1 and recoveries within 97–109%. Due to the low cost of HF-LPME and total time consumption, this methodology is ready for implementation in routine analytical laboratories.
Summary
A 50+ SPF sunscreen decreased significantly cutaneous vitamin D production following a single narrow-band (nb)UVB exposure, independently from the body surface area exposed. In contrast, the ...circulating 25(OH)D
3
levels were only minimally affected. It is probable that another endogenous source of precursors is selected when skin-originated precursors are lacking.
Purpose
Sunscreen use, highly advocated for preventing cutaneous carcinogenesis, is potentially leading to an aggravation of vitamin D deficiency with its consequences on bone health. The effect of sunscreens on circulating vitamin D levels remains debated. This study investigated the effect of sunscreen on cutaneous vitamin D production and circulating 25(OH)D
3
levels, according to different body surface areas (BSA).
Methods
Vitamin D and 25(OH)D
3
levels were measured in four groups exposed to a single nbUVB exposure on 9% (group I: head and hands), 23% (group II: head, hands and arms), 50% (group III: head, hands, arms and legs) and 96% (group IV: total body) of the body surface without and with a 50+ sun protection factor sunscreen.
Results
Sunscreen use decreased by 83, 88.3, 75.7 and 92.5% the cutaneous vitamin D production in groups I to IV, respectively, but only by 13.2, 10.5, 7.7 and 10.4% the values of circulating 25(OH)D
3,
correspondingly.
Conclusions
Although a 50+ sunscreen decreases significantly cutaneous vitamin D production following a single nbUVB exposure, and independently from the BSA, the circulating 25(OH)D
3
levels were only minimally affected. This could be explained by a switch to another endogenous source of precursors. Short-term sunscreen use probably does not affect circulating vitamin D levels and hence does not increase the risk for osteoporosis. The effect of long-term sunscreen use remains however to be determined.
•Development of an easy, fast and robust method for routine analysis of 3α-diol G.•Complete clinical and analytical validation of the proposed method in serum samples.•Establishment of new reference ...values for both genders in children and adults.
Androstanediol glucuronide is linked to a range of disorders of peripheral androgen formation and action, such as in hirsutism and acne. Nowadays its accurate quantification is still challenging and there are just a few LC-MS/MS methods available. Besides, their reference intervals for normal European populations by LC-MS/MS, including prepubertal and pubertal children, have not been reported yet.
Validation of the proposed new methodology was performed at 3 levels in triplicate during 3 different days. Calibration curve concentration ranged from 0.1 to 25 µg/L. For method comparison between ELISA and the newly developed LC-MS/MS method, 43 patient samples were tested. A reference interval study was performed with 264 healthy Belgian individuals (108 male and 156 female).
Validation of the proposed LC-MS/MS method was satisfactorily achieved, with mean imprecision values lower than 7.4%, mean recoveries within 99–108% and a limit of quantification of 0.059 µg/L. Compared to LC-MS/MS, ELISA showed a positive bias in serum samples, providing results 43% higher for the same sample. As a consequence, new reference intervals based on age and gender have been calculated.
An easy, fast and straightforward LC-MS/MS method for the determination of androstanediol glucuronide has been developed and fully validated. Besides, reference interval for normal European populations, including prepubertal and pubertal children has been established for the first time.
A stable isotope dilution liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed and validated for the determination of 24,25-dihydroxyvitamin D
3
(24,25(OH)
2
D
3
) and ...25-hydroxyvitamin D
3
/D
2
(25(OH)D
3
/D
2
) in human aqueous humor samples from the Eye-D study. Optimum sample preparation is based on simple liquid-liquid extraction (LLE) followed by derivatization with an Amplifex reagent prior to LC-MS/MS in order to enhance analyte sensitivity. The average recoveries for 24,25(OH)
2
D
3
(0.02, 0.05, 0.4 μg L
−1
), 25(OH)D
3
(0.2, 0.5,3.75 μg L
−1
) and 25(OH)D
2
(0.15, 0.4, 3 μg L
−1
) ranged from 92 to 112 with a coefficient of variance (CV) lower than 15%. The limits of quantitation (LOQs) were from 0.02 μg L
−1
(24,25(OH)
2
D
3
) to 0.2 μg L
−1
(25(OH)D
3
) using a sample volume of 50 μL. We demonstrated that the present method provides adequate sensitivity, selectivity, accuracy, and robustness to screen for vitamin D metabolites in aqueous humor samples by analyzing five samples which were withdrawn during cataract operation.
A stable isotope dilution liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed for the determination of 24,25-dihydroxyvitamin D
3
(24,25(OH)
2
D
3
) and 25-hydroxyvitamin D
3
/D
2
(25(OH)D
3
/D
2
) in human aqueous humor samples.
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