Tobias Alfvén

Imperial College London, London, ENG, United Kingdom

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Publications (5)24.73 Total impact

  • Article: Classification of anaphylaxis and utility of the EAACI Taskforce position paper on anaphylaxis in children.
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    ABSTRACT: Correct management and classification of anaphylaxis is mandatory. Records of emergency department (ED) visits to any of the three pediatric hospitals in Stockholm, because of reactions to foods during 2007, were identified. A retrospective analysis of clinical ED records of 371 children with 381 unique occasions of reactions to foods was performed. Symptoms/signs of reactions to foods recorded for classification of anaphylaxis were related to those presented in the EAACI Taskforce position paper on Anaphylaxis in Children (Allergy 2007; 62: 857). Forty-six different symptoms/signs of reactions to foods were retrieved. Several severe signs or symptoms from the respiratory tract and signs indicating reduced brain perfusion were not described in detail in the EAACI paper, hampering correct classification of anaphylaxis including grading of severity in our material. After modification of the EAACI classification including such signs and symptoms, we were able to classify 128 (35%) children with anaphylaxis. Seventy children (19%) did not fulfill our modified EAACI's criteria for anaphylaxis. They had been given adrenaline before or at arrival to hospital, possibly preventing anaphylaxis. Another 173 (47%) children/adolescents had neither been given adrenalin, nor fulfilled the criteria for anaphylaxis. Classification of food-induced anaphylaxis and severity grading should be built on signs and symptoms to facilitate diagnosis. The existing EAACI tool is helpful, but for Swedish children it is not quite applicable, in particular because of the lack of description of some respiratory, neurological or possible cardiovascular signs and symptoms.
    Pediatric Allergy and Immunology 06/2011; 22(4):369-73. · 2.46 Impact Factor
  • Article: Low level cadmium exposure, renal and bone effects--the OSCAR study.
    Lars Järup, Tobias Alfvén
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    ABSTRACT: It is well known that high cadmium exposure causes renal damage, osteoporosis and osteomalacia, whereas the dose-response relationships at low-level exposure are less well established. WHO estimated (1992) that a urinary excretion of 10 nmol/mmol creatinine would constitute a 'critical limit' below which kidney damage would not occur. Later, Belgian and Swedish studies have shown signs of cadmium induced kidney dysfunction in the general population already at urinary cadmium levels around 2-3 nmol/mmol creatinine. The Swedish OSCAR (OSteoporosis-CAdmium as a Risk factor) study comprised 1021 individuals, exposed to cadmium in the environment. Blood and urinary cadmium were used as dose estimates. Protein HC (alpha-1-microglobulin) was used as an indicator of renal tubular damage. Forearm bone mineral density (BMD) was assessed with DXA (dual energy x-ray absorptiometry) technique. The study showed that tubular proteinuria occurred at much lower levels of cadmium dose than previously known. A negative dose-effect relationship was found between cadmium dose and BMD for people at the age of 60 or older. In this age group, there was also a dose-response relationship, showing a three-fold increased risk of low BMD in the group with urinary cadmium over 3 nmol/mol creatinine, as compared to the lowest dose group. There was also evidence of an increased risk of forearm fractures with increasing cadmium levels in the population 50 years of age or older. The potential public health consequences of low level cadmium exposure should be recognized, and measures taken to reduce cadmium exposure to an absolute minimum.
    BioMetals 11/2004; 17(5):505-9. · 2.82 Impact Factor
  • Article: Cadmium exposure and distal forearm fractures.
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    ABSTRACT: The aim of this study was to analyze the relationship between low-level cadmium exposure and distal forearm fractures. Altogether, 1021 men and women exposed to cadmium in Sweden were included. The study indicates that cadmium exposure is associated with increased risk of forearm fractures in people over the age of 50. Very few studies have been performed on environmental risk factors for fractures. Cadmium is known to cause damage to the kidneys and in high doses to the bone. The aim of this study was to analyze the relationship between low-level cadmium exposure and distal forearm fractures. A total of 479 men and 542 women, 16-81 years of age, that were environmentally or occupationally exposed to cadmium were examined in 1997. Cadmium in urine was used to estimate dose, and information about previous fractures and risk factors for fractures was obtained from questionnaires. Fractures were validated using medical records. The association between cadmium dose and risk of forearm fracture was evaluated using Cox proportional hazard regression analysis. The mean urinary cadmium in the study population was 0.74 nmol cadmium/mmol creatinine (10% and 90% percentiles are 0.19 and 1.42, respectively). For fractures occurring after the age of 50 years (n = 558, 32 forearm fractures), the fracture hazard ratio, adjusted for gender and other relevant co-variates, increased by 18% (95% CI, 1.0-38%) per unit urinary cadmium (nmol cadmium/mmol creatinine). When subjects were grouped in exposure categories, the hazard ratio reached 3.5 (90% CI, 1.1, 11) in the group of subjects with urinary cadmium between 2 and 4 nmol/mmol creatinine and 8.8 (90% CI, 2.6, 30) in the group of subjects with > or = 4 nmol/mmol creatinine. Associations between cadmium and fracture risk were absent before the age of 50. Cadmium exposure is associated with increased risk of forearm fractures in people over 50 years of age.
    Journal of Bone and Mineral Research 07/2004; 19(6):900-5. · 6.37 Impact Factor
  • Source
    Article: Cadmium and lead in blood in relation to low bone mineral density and tubular proteinuria.
    Tobias Alfvén, Lars Järup, Carl-Gustaf Elinder
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    ABSTRACT: Long-term exposure to cadmium may cause kidney and bone damage. Urinary cadmium is commonly used as the dose estimate for the body burden of cadmium. However, elevated levels of cadmium in the urine may reflect not only high levels of cadmium dose but also renal dysfunction. In this study we used blood cadmium as the dose estimate. In addition, we analyzed blood lead. We examined 479 men and 542 women, ages 16-81 years, who were environmentally or occupationally exposed to cadmium and lead. We used urinary protein alpha 1-microglobulin as a marker for tubular proteinuria and measured forearm bone mineral density using dual-energy X-ray absorptiometry. The relationship between blood cadmium and tubular proteinuria was strong, even when we excluded occupationally exposed participants. The subgroup with the highest blood cadmium levels had a 4-fold risk of tubular proteinuria compared to the subgroup with the lowest blood cadmium levels. In the older age group (age > 60), the risk of low bone mineral density (z-score < -1) for the subgroup with the highest blood cadmium levels was almost 3-fold compared to the group with lowest blood cadmium levels. We found no similar associations for lead. The observed effects may be caused by higher cadmium exposure in the past. This study strengthens previous evidence that cadmium exposure may affect both bone mineral density and kidney function.
    Environmental Health Perspectives 07/2002; 110(7):699-702. · 7.04 Impact Factor
  • Article: Low‐Level Cadmium Exposure and Osteoporosis
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    ABSTRACT: Osteoporosis is a major cause of morbidity worldwide. A number of risk factors, such as age and gender, are well established. High cadmium exposure causes renal damage and in severe cases also causes osteoporosis and osteomalacia. We have examined whether long-term low-level cadmium exposure increases the risk of osteoporosis. Bone mineral density (BMD) in the forearm was measured in 520 men and 544 women, aged 16–81 years, environmentally or occupationally exposed to cadmium, using dual-energy X-ray absorptiometry (DXA) technique. Cadmium in urine was used as the dose estimate and protein HC was used as a marker of renal tubular damage. There was a clear dose-response relation between cadmium dose and the prevalence of tubular proteinuria. Inverse relations were found between cadmium dose, tubular proteinuria, and BMD, particularly apparent in persons over 60 years of age. There was a dose-response relation between cadmium dose and osteoporosis. The odds ratios (ORs) for men were 2.2 (95% CI, 1.0-4.8) in the dose group 0.5-3 nmol Cd/mmol creatinine and 5.3 (2.0-14) in the highest dose category (≥3 nmol/mmol creatinine) compared with the lowest dose group (<0.5 nmol Cd/mmol creatinine). For women, the OR was 1.8 (0.65-5.3) in the dose group 0.5-3 nmol Cd/mmol creatinine. We conclude that exposure to low levels of cadmium is associated with an increased risk of osteoporosis.
    Journal of bone and mineral research: the official journal of the American Society for Bone and Mineral Research 07/2000; 15(8):1579 - 1586. · 6.04 Impact Factor