| 1. |
- Andelin, M., et al.
(författare)
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Assessing the Accuracy of Continuous Glucose Monitoring (CGM) Calibrated With Capillary Values Using Capillary or Venous Glucose Levels as a Reference.
- 2016
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Ingår i: Journal of Diabetes Science and Technology. - : Diabetes Technology Society. - 1932-2968. ; 10:4, s. 876-884
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Tidskriftsartikel (refereegranskat)abstract
- Background: Using the standard venous reference for the evaluation of continuous glucose monitoring (CGM) systems could possibly negatively affect measured CGM accuracy since CGM are generally calibrated with capillary glucose and venous and capillary glucose concentrations differ. We therefore aimed to quantify the effect of using capillary versus venous glucose reference samples on estimated accuracy in capillary calibrated CGM.less thanbr /greater thanMethods: We evaluated 41 individuals with type 1 diabetes mellitus (T1DM) using the Dexcom G4 CGM system over 6 days. Patients calibrated their CGM devices with capillary glucose by means of the HemoCue system. During 2 visits, capillary and venous samples were simultaneously measured by HemoCue and compared to concomitantly obtained CGM readings. The mean absolute relative difference (MARD) was calculated using capillary and venous reference samples.less thanbr /greater thanResults: Venous glucose values were 0.83 mmol/L (15.0 mg/dl) lower than capillary values over all glycemic ranges, P less than .0001. Below 4 mmol/l (72 mg/dl), the difference was 1.25 mmol/l (22.5 mg/dl), P = .0001, at 4-10 mmol/l (72-180 mg/dl), 0.67 mmol/l (12.0 mg/dl), P less than .0001 and above 10 mmol/l (180 mg/dl), 0.95 mmol/l (17.1 mg/dl), P less than .0001. MARD was 11.7% using capillary values as reference compared to 13.7% using venous samples, P = .037. Below 4 mmol/l (72 mg/dl) MARD was 16.6% and 31.8%, P = .048, at 4-10 mmol/l (72-180 mg/dl) 12.1% and 12.6%, P = .32, above 10 mmol/l (180 mg/dl) 8.7% and 9.2%, P = .82.less thanbr /greater thanConclusion: Using capillary glucose concentrations as reference to evaluate the accuracy of CGM calibrated with capillary samples is associated with a lower MARD than using venous glucose as the reference. Capillary glucose concentrations were significantly higher than venous in all glycemic ranges.less thanbr /greater than (© 2016 Diabetes Technology Society.)
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| 2. |
- Sörbo, Ann, et al.
(författare)
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Hair Cortisol as a Biomarker of Stress before and after Subarachnoid Hemorrhage : A Case Report
- 2017
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Ingår i: Remedy Open Access. - : Remedy Publications. - 2573-6078. ; 2
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Tidskriftsartikel (refereegranskat)abstract
- The aim was to study stress in the acute and post-acute phase in patients with severe traumaticbrain injury (TBI) or non-traumatic subarachnoid hemorrhage (SAH) who were treated at theneurointensive care unit (NICU). Hair cortisol is a biomarker of stress via alterations in hypothalamuspituitary-adrenal axis activity, where cortisol from plasma is continuously incorporated intogrowing hairs at their roots. As hair grows at an average of 1 cm/month, concentrations of haircortisol can also be used to measure stress levels retrospectively.Hair samples were collected at an interval of one month until three months, with the first cut atadmission to the NICU. The patients (or their relatives, if the patient was unable to communicate)were interviewed about psychological or physical stressors during the previous months.We present a 28-year-old woman suffering from a subarachnoid hemorrhage (SAH), studied withrepeated haircuts. She experienced the sudden onset of a severe headache. The general practitionersdiagnosed it as migraine or wry neck. Three weeks later, she experienced another attack ofsevere headache. A CT scan showed an SAH. Six months after the SAH, the patient developedhydrocephalus and was successfully treated with a VP shunt. In this case, hair cortisol was elevatedduring the pre-hospital month (probably because of pain and stress due to a sentinel or “warning”leak), during the intensive care period and until two months after the SAH. It then normalized, butit was elevated again at the time at which the patient developed hydrocephalus. At the nine-monthhaircut, her hair cortisol had again normalized.This case indicates that hair cortisol measurement is a promising method for studying stress,retrospectively and during recovery, in patients suffering from SAH.
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| 3. |
- El-Khoury, Joe M., et al.
(författare)
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Time to Reevaluate the 95% Inclusion Criteria for Defining Reference Intervals?
- 2024
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Ingår i: Clinical Chemistry. - : OXFORD UNIV PRESS INC. - 0009-9147 .- 1530-8561.
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- When test results fall outside the reference intervals in healthy individuals, it often leads to frustration and unnecessary investigations for potential diseases. These anomalies can be attributed to matrix effects or lack of selectivity but more commonly are due to the strict criteria we use when designing reference intervals that ultimately could be narrow for some tests (1–3).The central question we raise here is whether it is time to reevaluate and redesign our approach to creating reference intervals to reduce the occurrence of false positives while minimizing false negatives. Here we provide a condensed overview of the history, theory, and practical considerations regarding reference intervals and why we firmly believe we need to update our approach for some tests.
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| 4. |
- Grankvist, Kjell, et al.
(författare)
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Laboratoriernas verksamhet
- 2018. - 10
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Ingår i: Laurells Klinisk kemi i praktisk medicin. - Lund : Studentlitteratur AB. - 9789144119748 ; , s. 13-30
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Bokkapitel (refereegranskat)
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| 5. |
- Greaves, Ronda F, et al.
(författare)
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The IFCC Curriculum - phase 1.
- 2018
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Ingår i: EJIFCC. - 1650-3414. ; 29:1, s. 55-93
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Tidskriftsartikel (refereegranskat)
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| 6. |
- Hammarsten, Ola, et al.
(författare)
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Tolkning av analysresultat
- 2018. - 10
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Ingår i: Laurells Klinisk kemi i praktisk medicin. - Lund : Studentlitteratur AB. - 9789144119748 ; , s. 31-53
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Bokkapitel (refereegranskat)
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| 7. |
- Jacobsson, Stefan, et al.
(författare)
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Anemier
- 2018. - 10
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Ingår i: Laurells klinisk kemi i praktisk medicin. - Lund : Studentlitteratur AB. - 9789144119748 ; , s. 209-264
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 8. |
- Kallner, Anders, et al.
(författare)
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An experimental study of methods for the analysis of variance components in the inference of laboratory information
- 2020
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Ingår i: Scandinavian Journal of Clinical and Laboratory Investigation. - : TAYLOR & FRANCIS LTD. - 0036-5513 .- 1502-7686. ; 80:1, s. 73-80
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Tidskriftsartikel (refereegranskat)abstract
- Measurement uncertainty (MU) can be estimated and calculated by different procedures, representing different aspects and intended use. It is appropriate to distinguish between uncertainty determined under repeatability and reproducibility conditions, and to distinguish causes of variation using analysis of variance components. The intra-laboratory MU is frequently determined by repeated measurements of control material(s) of one or several concentrations during a prolonged period of time. We demonstrate, based on experimental results, how such results can be used to identify the repeatability, pure reproducibility and intra-laboratory variance as the sum of the two. Native patient material was used to establish repeatability using the Dahlberg formula for random differences between measurements and an expanded Dahlberg formula if a non-random difference, e.g. bias, was expected. Repeatability and reproducibility have different clinical relevance in intensive care compared to monitoring treatment of chronic diseases, comparison with reference intervals or screening.
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| 9. |
- Kallner, Anders, et al.
(författare)
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Measurement repeatability profiles of eight frequently requested measurands in clinical chemistry determined by duplicate measurements of patient samples
- 2020
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Ingår i: Scandinavian Journal of Clinical and Laboratory Investigation. - : TAYLOR & FRANCIS LTD. - 0036-5513 .- 1502-7686. ; 80:3, s. 202-209
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Tidskriftsartikel (refereegranskat)abstract
- Measurement uncertainties in clinical chemistry are commonly regarded as heteroscedastic - having a constant relative standard deviation irrespective of the concentration of the measurand. The uncertainty is usually determined at two concentrations using stabilized control materials and assumed to represent the analytical goal. The purpose of the present study was to use duplicates of unselected patient samples to calculate the absolute and relative repeatability component of the intra-laboratory measurement uncertainty from duplicates, using the Dahlberg formula and analysis of variance components. Estimates were made at five different concentration intervals of ALT, AST, Calcium, Cholesterol, Creatinine, CRP, Triglycerides and TSH covering the entire concentration interval of the patient cohort. This partioning allows detailing their repeatability profiles. The calculations of the profiles were based on randomly selected results from sets of duplicates ranging from 12,000 to 65,000 pairs. The repeatability of the measurands showed substantial variability within the measuring interval. Therefore, characterizing imprecision profiles as purely homo- or heteroscedastic or by a single number may not be optimal for the intended use. The present data make a case for nuancing the evaluation of analytical goals and minimal differences of measurement results by establishing uncertainty profiles under repeatability conditions, using natural patient samples.
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| 10. |
- Kallner, Anders, et al.
(författare)
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Repeatability imprecision from analysis of duplicates of patient samples and control materials
- 2020
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Ingår i: Scandinavian Journal of Clinical and Laboratory Investigation. - : TAYLOR & FRANCIS LTD. - 0036-5513 .- 1502-7686. ; 80:3, s. 210-214
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Tidskriftsartikel (refereegranskat)abstract
- Measurement imprecision is usually calculated from measurement results of the same stabilized control material(s) obtained over time, and is therefore, principally, only valid at the concentration(s) of the selected control material(s). The resulting uncertainty has been obtained under reproducibility conditions and corresponds to the conventional analytical goals. Furthermore, the commutability of the control materials used determines whether the imprecision calculated from the control materials reflects the imprecision of measuring patient samples. Imprecision estimated by measurements of patient samples uses fully commutable samples, freely available in the laboratories. It is commonly performed by calculating the results of routine patient samples measured twice each. Since the duplicates are usually analysed throughout the entire concentration interval of the patient samples processed in the laboratory, the result will be a weighted average of the repeatability imprecision measured in the chosen measurement intervals or throughout the entire interval of concentrations encountered in patient care. In contrast, the uncertainty derived from many measurements of control materials over periods of weeks is usually made under reproducibility conditions. Consequently, the repeatability and reproducibility imprecision play different roles in the inference of results in clinical medicine. The purpose of the present review is to detail the properties of the imprecision calculated by duplicates of natural samples, to explain how it differs from imprecision calculated from single concentrations of control materials, and to elucidate what precautions need to be taken in case of bias, e.g. due to carry-over effects.
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