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Ridefelt, Peter
Alternative names
Publications (10 of 28) Show all publications
Öhrvik, V., Warensjö, E., Nälsén, C., Becker, W., Ridefelt, P. & Lindroos, A. K. (2018). Dietary intake and biomarker status of folate in Swedish adults. European Journal of Nutrition, 57(2), 451-462
Open this publication in new window or tab >>Dietary intake and biomarker status of folate in Swedish adults
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2018 (English)In: European Journal of Nutrition, ISSN 1436-6207, E-ISSN 1436-6215, Vol. 57, no 2, p. 451-462Article in journal (Refereed) Published
Abstract [en]

PURPOSE: National data on folate status are missing in Sweden, and regional data indicate folate insufficiency in up to more than 25% of the study populations. The objectives were to determine folate intake and status in the adult Swedish population as well as identifying dietary patterns associated with beneficial folate status.

METHODS: Folate intake was estimated using a web-based 4-d food record in adults aged 18-80 years (n = 1797). Folate status was measured as erythrocyte (n = 282) and plasma folate concentrations (n = 294). Factor analysis was used to derive a dietary pattern associated with a higher folate status.

RESULTS: Median folate intake was 246 µg/day (Q 1 = 196, Q 3 = 304, n = 1797) and for women of reproductive age 227 µg/day (Q 1 = 181, Q 3 = 282, n = 450). As dietary folate equivalents (DFE), median intake was 257 µg/day (Q 1 = 201, Q 3 = 323) and for women of reproductive age 239 µg/day (Q 1 = 185, Q 3 = 300). Low blood folate concentrations were found in 2% (erythrocyte concentrations <317 nmol/L) and 4% (plasma concentrations <6.8 nmol/L) of the participants, respectively. None of the women of reproductive age had erythrocyte folate concentrations associated with the lowest risk of neural tube defects. Dietary patterns associated with higher folate status were rich in vegetables, pulses and roots as well as cheese and alcoholic beverages, and low in meat.

CONCLUSIONS: Prevalence of low erythrocyte folate concentrations was low in this population, and estimated dietary intakes are well above average requirement. However, to obtain a folate status optimal for prevention of neural tube defects major dietary changes are required and folic acid supplements recommended prior to conception.

National Category
Public Health, Global Health, Social Medicine and Epidemiology
Identifiers
urn:nbn:se:uu:diva-307922 (URN)10.1007/s00394-016-1328-4 (DOI)000427285000004 ()27787623 (PubMedID)
Available from: 2016-11-22 Created: 2016-11-22 Last updated: 2018-05-23Bibliographically approved
Lopes, R. D., Rordorf, R., De Ferrari, G. M., Leonardi, S., Thomas, L., Wojdyla, D. M., . . . Wallentin, L. (2018). Digoxin and Mortality in Patients With Atrial Fibrillation. Journal of the American College of Cardiology, 71(10), 1063-1074
Open this publication in new window or tab >>Digoxin and Mortality in Patients With Atrial Fibrillation
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2018 (English)In: Journal of the American College of Cardiology, ISSN 0735-1097, E-ISSN 1558-3597, Vol. 71, no 10, p. 1063-1074Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: Digoxin is widely used in patients with atrial fibrillation (AF). OBJECTIVES The goal of this paper was to explore whether digoxin use was independently associated with increased mortality in patients with AF and if the association was modified by heart failure and/or serum digoxin concentration.

METHODS: The association between digoxin use and mortality was assessed in 17,897 patients by using a propensity score-adjusted analysis and in new digoxin users during the trial versus propensity score-matched control participants. The authors investigated the independent association between serum digoxin concentration and mortality after multivariable adjustment.

RESULTS: At baseline, 5,824 (32.5%) patients were receiving digoxin. Baseline digoxin use was not associated with an increased risk of death (adjusted hazard ratio [HR]: 1.09; 95% confidence interval [CI]: 0.96 to 1.23; p = 0.19). However, patients with a serum digoxin concentration $ 1.2 ng/ml had a 56% increased hazard of mortality (adjusted HR: 1.56; 95% CI: 1.20 to 2.04) compared with those not on digoxin. When analyzed as a continuous variable, serum digoxin concentration was associated with a 19% higher adjusted hazard of death for each 0.5-ng/ml increase (p = 0.0010); these results were similar for patients with and without heart failure. Compared with propensity score-matched control participants, the risk of death (adjusted HR: 1.78; 95% CI: 1.37 to 2.31) and sudden death (adjusted HR: 2.14; 95% CI: 1.11 to 4.12) was significantly higher in new digoxin users.

CONCLUSIONS: In patients with AF taking digoxin, the risk of death was independently related to serum digoxin concentration and was highest in patients with concentrations $ 1.2 ng/ml. Initiating digoxin was independently associated with higher mortality in patients with AF, regardless of heart failure.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE INC, 2018
Keywords
atrial fibrillation, digoxin, heart failure, mortality
National Category
Cardiac and Cardiovascular Systems
Identifiers
urn:nbn:se:uu:diva-350280 (URN)10.1016/j.jacc.2017.12.060 (DOI)000426569700001 ()29519345 (PubMedID)
Available from: 2018-05-09 Created: 2018-05-09 Last updated: 2018-05-09Bibliographically approved
Larsson, A. & Ridefelt, P. (2018). Pediatric reference intervals for liver markers derived from healthy community-based subjects will improve diagnostic interpretation in children and adolescents. Journal of Laboratory and Precision Medicine, 3, 2
Open this publication in new window or tab >>Pediatric reference intervals for liver markers derived from healthy community-based subjects will improve diagnostic interpretation in children and adolescents
2018 (English)In: Journal of Laboratory and Precision Medicine, ISSN 2519-9005, Vol. 3, p. 2-Article in journal (Refereed) Published
Place, publisher, year, edition, pages
Uppsala: , 2018
National Category
Clinical Laboratory Medicine
Research subject
Clinical Chemistry
Identifiers
urn:nbn:se:uu:diva-343000 (URN)10.21037/jlpm.2018.01.01 (DOI)
Available from: 2018-02-24 Created: 2018-02-24 Last updated: 2018-03-15Bibliographically approved
Gyllenhammar, I., Diderholm, B., Gustafsson, J., Berger, U., Ridefelt, P., Benskin, J. P., . . . Glynn, A. (2018). Perfluoroalkyl acid levels in first-time mothers in relation to offspring weight gain and growth. Environment International, 111, 191-199
Open this publication in new window or tab >>Perfluoroalkyl acid levels in first-time mothers in relation to offspring weight gain and growth
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2018 (English)In: Environment International, ISSN 0160-4120, E-ISSN 1873-6750, Vol. 111, p. 191-199Article in journal (Refereed) Published
Abstract [en]

We investigated if maternal body burdens of perfluoroalkyl acids (PFAAs) at the time of delivery are associated with birth outcome and if early life exposure (in utero/nursing) is associated with early childhood growth and weight gain. Maternal PFAA body burdens were estimated by analysis of serum samples from mothers living in Uppsala County, Sweden (POPUP), sampled three weeks after delivery between 1996 and 2011. Data on child length and weight were collected from medical records and converted into standard deviation scores (SDS). Multiple linear regression models with appropriate covariates were used to analyze associations between maternal PFAA levels and birth outcomes (n=381). After birth Generalized Least Squares models were used to analyze associations between maternal PFAA and child growth (n=200). Inverse associations were found between maternal levels of perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), and perfluoroundecanoic acid (PFUnDA), and birth weight SDS with a change of -0.10 to -0.18 weight SDS for an inter-quartile range (IQR) increase in ng/g PFAA. After birth, weight and length SDS were not significantly associated with maternal PFAA. However, BMI SDS was significantly associated with PFOA, PFNA, and PFHxS at 3 and 4years of age, and with PFOS at 4 and 5years of age. If causal, these associations suggest that PFAA affects fetal and childhood body development in different directions.

National Category
Clinical Medicine
Identifiers
urn:nbn:se:uu:diva-343486 (URN)10.1016/j.envint.2017.12.002 (DOI)000423441500020 ()29223808 (PubMedID)
Funder
Swedish Environmental Protection Agency, 219 1202Swedish Research Council Formas, 2010-1300Swedish Civil Contingencies Agency, dnr 1637/2012
Available from: 2018-02-27 Created: 2018-02-27 Last updated: 2018-03-07Bibliographically approved
Ridefelt, P. & Helmersson-Karlqvist, J. (2017). Albumin adjustment of total calcium does not improve the estimation of calcium status. Scandinavian Journal of Clinical and Laboratory Investigation, 77(6), 442-447
Open this publication in new window or tab >>Albumin adjustment of total calcium does not improve the estimation of calcium status
2017 (English)In: Scandinavian Journal of Clinical and Laboratory Investigation, ISSN 0036-5513, E-ISSN 1502-7686, Vol. 77, no 6, p. 442-447Article in journal (Refereed) Published
Abstract [en]

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 (<30g/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.

Keywords
Calcium, human, hypercalcemia, hypocalcemia, plasma albumin
National Category
Clinical Laboratory Medicine
Identifiers
urn:nbn:se:uu:diva-335545 (URN)10.1080/00365513.2017.1336568 (DOI)000409183500009 ()28613958 (PubMedID)
Available from: 2017-12-06 Created: 2017-12-06 Last updated: 2017-12-06Bibliographically approved
Bjermo, H., Aune, M., Cantillana, T., Glynn, A., Lind, P. M., Ridefelt, P. & Darnerud, P. O. (2017). Serum levels of brominated flame retardants (BFRs: PBDE, HBCD) and influence of dietary factors in a population-based study on Swedish adults. Chemosphere, 167, 485-491
Open this publication in new window or tab >>Serum levels of brominated flame retardants (BFRs: PBDE, HBCD) and influence of dietary factors in a population-based study on Swedish adults
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2017 (English)In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 167, p. 485-491Article in journal (Refereed) Published
Abstract [en]

The aim of this study was to investigate associations between serum concentrations of brominated flame retardants and personal characteristics, including diet, in adults participating in a population-based study in Sweden 2010-11. Moreover, observed concentrations were used in a health risk assessment, using published health-based reference values. Serum samples of 170 adult individuals of both sexes were analyzed for 10 PBDE congeners and HBCD by GC-MS. When including concentrations between LOD and LOQ, highest median serum concentration was observed for BDE-153 (1.2 ng/g serum lipid), followed by BDE-209 (0.95 ng/g lipid), BDE-47 (0.49 ng/g lipid) and BDE-100 (0.21 ng/g lipid). Median concentration of HBCD was 0.10 ng/g lipid. A few markedly elevated concentrations of BDE-209, HBCD (77-78 ng/g lipid) and BDE-47 (44 ng/g lipid) were observed. The only statistical significant findings were higher BDE-153 concentrations in men than in women, and positive associations between serum BDE-153 concentrations and consumption of fish (total), beef, mutton and poultry. PBDE concentrations were in accordance with concentrations reported in other European countries but generally lower than those found in North America. Median PBDE serum concentrations observed in adults from Sweden suggest sufficient health protection, when compared with published health-based reference values, although some outliers with high serum concentrations had lower safety margins.

Keywords
Brominated flame retardants, PBDE, HBCD, Serum, Population-based survey, Diet
National Category
Public Health, Global Health, Social Medicine and Epidemiology Pharmacology and Toxicology
Identifiers
urn:nbn:se:uu:diva-311167 (URN)10.1016/j.chemosphere.2016.10.008 (DOI)000388543400057 ()27750173 (PubMedID)
Funder
Swedish Environmental Protection Agency
Available from: 2016-12-22 Created: 2016-12-22 Last updated: 2018-01-13Bibliographically approved
Helmersson, J., Ridefelt, P., Lind, L. & Larsson, A. (2016). Reference values for 34 frequently used laboratory tests in 80-year-old men and women. Maturitas, 92, 97-101
Open this publication in new window or tab >>Reference values for 34 frequently used laboratory tests in 80-year-old men and women
2016 (English)In: Maturitas, ISSN 0378-5122, E-ISSN 1873-4111, Vol. 92, p. 97-101Article in journal (Refereed) Published
Abstract [en]

OBJECTIVES: Reference values are usually based on blood samples from healthy individuals in the age range 20-50 years. Most patients seeking health care are older than this reference population. Many reference intervals are age dependent and there is thus a need to have appropriate reference intervals also for elderly individuals.

METHODS: We analyzed a group of frequently used laboratory tests in an 80-year-old population (n=531, 266 females and 265 males). The 2.5th and 97.5th percentiles for these markers were calculated according to the International Federation of Clinical Chemistry guidelines on the statistical treatment of reference values.

RESULTS: Reference values are reported for serum alanine transaminase (ALT), albumin, alkaline phosphatase, pancreatic amylase, apolipoprotein A1, apolipoprotein B, apolipoprotein B/apolipoprotein A1 ratio, aspartate aminotransferase (AST), AST/ALT ratio, bilirubin, calcium, calprotectin, cholesterol, HDL-cholesterol, creatinine kinase (CK), creatinine, creatinine estimated GFR, C-reactive protein, cystatin C, cystatin C estimated GFR, gamma-glutamyltransferase (GGT), iron, iron saturation, lactate dehydrogenase (LDH), magnesium, phosphate, transferrin, triglycerides, urate, urea, zinc, hemoglobin, platelet count and white blood cell count. The upper reference limit for creatinine and urea was significantly increased while the lower limit for iron and albumin was decreased in this elderly population in comparison with the population in the Nordic Reference Interval Project (NORIP).

CONCLUSIONS: Reference values calculated from the whole population and a subpopulation without cardiovascular disease showed strong concordance. Several of the reference interval limits were outside the 90% confidence interval of NORIP.

National Category
Clinical Laboratory Medicine
Identifiers
urn:nbn:se:uu:diva-303898 (URN)10.1016/j.maturitas.2016.07.015 (DOI)000384787700016 ()27621245 (PubMedID)
Available from: 2016-09-26 Created: 2016-09-26 Last updated: 2017-11-21Bibliographically approved
Ridefelt, P. (2015). Population-Based Pediatric Reference Intervals in General Clinical Chemistry: A Swedish Survey. Journal of Medical Biochemistry, 34(1), 64-65
Open this publication in new window or tab >>Population-Based Pediatric Reference Intervals in General Clinical Chemistry: A Swedish Survey
2015 (English)In: Journal of Medical Biochemistry, ISSN 1452-8258, E-ISSN 1452-8266, Vol. 34, no 1, p. 64-65Article in journal (Refereed) Published
Abstract [en]

Very few high quality studies on pediatric reference intervals for general clinical chemistry and hematology analytes have been performed. Three recent prospective community-based projects utilising blood samples from healthy children in Sweden, Denmark and Canada have substantially improved the situation. The Swedish survey included 701 healthy children. Reference intervals for general clinical chemistry and hematology were defined.

Keywords
biomarker, children, clinical chemistry tests, pediatric, reference interval, reference range
National Category
Biochemistry and Molecular Biology
Identifiers
urn:nbn:se:uu:diva-238390 (URN)10.2478/jomb-2014-0050 (DOI)000344055500011 ()
Available from: 2014-12-17 Created: 2014-12-12 Last updated: 2017-12-05Bibliographically approved
Larsson, A., Ridefelt, P., Melhus, H. & Lind, L. (2015). Reference intervals for parathyroid hormone for 70-year-old males and females: exclusion of individuals from the reference interval based on sex, calcium, diabetes, cardiovascular diseases or reduced kidney function has limited effects on the interval. Annals of Clinical Biochemistry, 52(1), 39-43
Open this publication in new window or tab >>Reference intervals for parathyroid hormone for 70-year-old males and females: exclusion of individuals from the reference interval based on sex, calcium, diabetes, cardiovascular diseases or reduced kidney function has limited effects on the interval
2015 (English)In: Annals of Clinical Biochemistry, ISSN 0004-5632, E-ISSN 1758-1001, Vol. 52, no 1, p. 39-43Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: A problem when producing reference intervals for elderly individuals is that they often suffer from a number of diseases and they are most often on medication. If all such persons are excluded, there is a risk that the residual subgroup may not be representative of the population, we therefore wanted to compare the effects different exclusion criteria has on the reference intervals.

METHODS: We measured parathyroid hormone (PTH), calcium, albumin and cystatin C in a cohort of 70-year-old males and females (n = 1003). Reference intervals for PTH for males and females were calculated for the entire population and after exclusion of persons with calcium >2.60 mmol/L, calcium >2.51 mmol/L, diabetes, reduced glomerular filtration rate (GFR), and cardiovascular diseases.

RESULTS: The calculated PTH reference interval 16 (CI 14-17) to 94 (CI 87-101) ng/L. Exclusion of study subjects resulted in smaller reference sample groups, but the reference limits remained within the 90% confidence intervals of the original reference limits. The selections thus had a very limited effect on the calculated reference interval for PTH.

CONCLUSIONS: Exclusion of elderly individuals with high calcium concentrations, diabetes, reduced GFR or cardiovascular disease has little effect on the reference interval for PTH. It is better not to exclude these individuals, as it will provide a broader base for the reference interval.

National Category
Clinical Laboratory Medicine
Identifiers
urn:nbn:se:uu:diva-220509 (URN)10.1177/0004563214526170 (DOI)000346418300004 ()24619764 (PubMedID)
Available from: 2014-03-17 Created: 2014-03-17 Last updated: 2017-12-05Bibliographically approved
Warensjö Lemming, E., Nälsén, C., Becker, W., Ridefelt, P., Mattisson, I. & Lindroos, A. K. (2015). Relative validation of the dietary intake of fatty acids among adults in the Swedish National Dietary Survey using plasma phospholipid fatty acid composition.. Journal of Nutritional Science, 4
Open this publication in new window or tab >>Relative validation of the dietary intake of fatty acids among adults in the Swedish National Dietary Survey using plasma phospholipid fatty acid composition.
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2015 (English)In: Journal of Nutritional Science, ISSN 2048-6790, E-ISSN 2048-6790, Vol. 4Article in journal (Refereed) Published
Abstract [en]

The aims of a national dietary study are several-fold. One purpose is to monitor the intake of foods and nutrients in the population and to compare intakes with dietary recommendations. It is, however, difficult to measure dietary fat intake and plasma biomarker fatty acid (FA) composition may be used as an objective measure of dietary fat intake. Thus, the relative ability of a diet record to capture habitual fat intake was validated against biomarker FA. Dietary fat intake was measured in a novel self-assisted web-based 4-d food record - the 'Riksmaten' method. Spearman rank correlations between dietary FA, certain food groups (fish-shellfish, dairy products, meat and sausages, and spreads) and the fat content of these food groups and biomarker FA were explored. Participants were 150 women and 129 men, aged 18-80 years, who took part in the Swedish National Dietary Survey, Riksmaten adults 2010-11. Blood samples were collected on average 20 d after the diet record and FA composition was measured in plasma phospholipids by GLC. Total n-3 FA (r 0·31), EPA (r 0·34) and DHA (r 0·42) were correlated between plasma and diet (all P ≤ 0·001). Adjustment for covariates attenuated the relationships. Linoleic acid was only marginally correlated (r 0·15; P = 0·06) in women. Plasma pentadecaenoic acid and heptadecaenoic acid were correlated with dairy product intake as previously reported. In conclusion, the Riksmaten method appears valid for the purpose of collecting data on dietary fat composition, at least in a healthy adult population.

National Category
Clinical Medicine
Identifiers
urn:nbn:se:uu:diva-278195 (URN)10.1017/jns.2015.1 (DOI)000362528100001 ()26495117 (PubMedID)
Available from: 2016-02-24 Created: 2016-02-24 Last updated: 2017-11-23Bibliographically approved
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