- Email: [email protected]
Use of proper diagnostic methods will provide more reliable results
Steroids 96 (2015) 169
Contents lists available at ScienceDirect
Steroids journal homepage: www.elsevier.com/locate/steroids
EDITORIAL Use of proper diagnostic methods will provide more reliable results
Dear editor, We read with great interest the recently published article by Ortega et al. in which the authors aimed to evaluate circulating non-esterified fatty acid (NEFA) levels in population-based samples of prepubertal children and adolescents and to analyze the association of NEFA with obesity, insulin resistance (IR), and sexual hormones in adolescents. They concluded that NEFA levels decrease with age in adolescents and were not significantly increased in obese children, supporting the fact that the decreased insulin sensitivity at this age was not affecting NEFA metabolism. Although SHBG was related to insulin and HOMA independently of age in both sexes, SHBG levels were not associated with NEFA [1]. However, we think that there are some points that should be emphasized about this study. First, authors used RIA and IRMA methods to measure testosterone, estradiol, sex hormone binding globulin (SHBG) and serum insulin concentrations. Accurate measurement of hormones is the pivot and requirement of modern endocrinology. As is known, there are some limitations of immunoassay (IA) methods such as low analytical specificity and inaccuracy that are inherent in many IA. There might be up to 2.8, 9.0, and 3.3-fold differences in results for testosterone, estradiol, and progesterone, respectively, between different IA methods as clearly seen from the 2008 Collage of American Pathologist (CAP) proficiency testing (PT) survey. Stanczyk et al. also state that lack of standardization of steroid hormone assays is a major deficiency in epidemiologic studies [2]. Especially in children, some steroid hormone measurements like direct estradiol IAs are problematic due to the lack of accuracy [3]. For the reliable measurement of parameters, if available, authors could prefer more specific and accurate mass spectrometry methods, which have superior limits of quantification. Second, NEFA levels in plasma were measured by an enzymatic colorimetric method in the original study. However, in the literature, there are several chromatographic methods, which can analyze several FAs, both esterified fatty acids (EFAs) and NEFAs, simultaneously [4,5]. Measurement of concentration of FA subtypes (EFAs and NEFAs), calculation of percentage of FA fractions or ratio of some fractions of FAs might be a better indicator to understand the association of FAs with obesity and IR in adolescents [6]. Accordingly, detailed analysis of FA subtypes can provide valuable information in management of dietary intake or supplementation of FAs, which are deficient in adolescents with obesity and IR. In conclusion, using current diagnostic methods with high sensitivity and specificity will provide more reliable results.
http://dx.doi.org/10.1016/j.steroids.2014.10.006 0039-128X/Ó 2014 Elsevier Inc. All rights reserved.
Conflict of interest The authors state that there is no conflict of interests regarding the publication of this paper. References [1] Ortega L, Garcia-Anguita A, Riestra P, Ortega H, Soriano-Guillén L, Lasunción MA, et al. Plasma non-esterified fatty acid levels in children and their relationship with sex steroids. Steroids 2014;88:15–8. [2] Ankarberg-Lindgren C, Norjavaara E. A purification step prior to commercial sensitive immunoassay is necessary to achieve clinical usefulness when quantifying serum 17b-estradiol in prepubertal children. Eur J Endocrinol 2008;158:117–24. [3] Stanczyk FZ, Lee JS, Santen RJ. Standardization of steroid hormone assays: why, how, and when? Cancer Epidemiol Biomarkers Prev 2007;16:1713–9. [4] Han LD, Xia JF, Liang QL, Wang Y, Wang YM, Hu P, et al. Plasma esterified and non-esterified fatty acids metabolic profiling using gas chromatography–mass spectrometry and its application in the study of diabetic mellitus and diabetic nephropathy. Anal Chim Acta 2011;689:85–91. [5] Trufelli H, Famiglini G, Termopoli V, Cappiello A. Profiling of non-esterified fatty acids in human plasma using liquid chromatography-electron ionization mass spectrometry. Anal Bioanal Chem 2011;400:2933–41. [6] Gunes O, Tascilar E, Sertoglu E, Tas A, Serdar MA, Kaya G, et al. Associations between erythrocyte membrane fatty acid compositions and insulin resistance in obese adolescents. Chem Phys Lipids 2014. http://dx.doi.org/10.1016/ j.chemphyslip.2014.09.006. pii: S0009-3084(14)00120-0 [Epub ahead of print].
⇑
Erdim Sertoglu Ankara Mevki Military Hospital, Anittepe Dispensary, Biochemistry Laboratory, Ankara, Turkey ⇑ Tel.: +90 507 140 3616; fax: +90 312 304 3300. E-mail address: [email protected] Metin Uyanik Corlu Military Hospital, Biochemistry Laboratory, Tekirdag, Turkey Huseyin Kayadibi Adana Military Hospital, Biochemistry Laboratory, Adana, Turkey Serkan Tapan Gulhane School of Medicine, Department of Medical Biochemistry, Ankara, Turkey Available online 20 November 2014
Contents lists available at ScienceDirect
Steroids journal homepage: www.elsevier.com/locate/steroids
EDITORIAL Use of proper diagnostic methods will provide more reliable results
Dear editor, We read with great interest the recently published article by Ortega et al. in which the authors aimed to evaluate circulating non-esterified fatty acid (NEFA) levels in population-based samples of prepubertal children and adolescents and to analyze the association of NEFA with obesity, insulin resistance (IR), and sexual hormones in adolescents. They concluded that NEFA levels decrease with age in adolescents and were not significantly increased in obese children, supporting the fact that the decreased insulin sensitivity at this age was not affecting NEFA metabolism. Although SHBG was related to insulin and HOMA independently of age in both sexes, SHBG levels were not associated with NEFA [1]. However, we think that there are some points that should be emphasized about this study. First, authors used RIA and IRMA methods to measure testosterone, estradiol, sex hormone binding globulin (SHBG) and serum insulin concentrations. Accurate measurement of hormones is the pivot and requirement of modern endocrinology. As is known, there are some limitations of immunoassay (IA) methods such as low analytical specificity and inaccuracy that are inherent in many IA. There might be up to 2.8, 9.0, and 3.3-fold differences in results for testosterone, estradiol, and progesterone, respectively, between different IA methods as clearly seen from the 2008 Collage of American Pathologist (CAP) proficiency testing (PT) survey. Stanczyk et al. also state that lack of standardization of steroid hormone assays is a major deficiency in epidemiologic studies [2]. Especially in children, some steroid hormone measurements like direct estradiol IAs are problematic due to the lack of accuracy [3]. For the reliable measurement of parameters, if available, authors could prefer more specific and accurate mass spectrometry methods, which have superior limits of quantification. Second, NEFA levels in plasma were measured by an enzymatic colorimetric method in the original study. However, in the literature, there are several chromatographic methods, which can analyze several FAs, both esterified fatty acids (EFAs) and NEFAs, simultaneously [4,5]. Measurement of concentration of FA subtypes (EFAs and NEFAs), calculation of percentage of FA fractions or ratio of some fractions of FAs might be a better indicator to understand the association of FAs with obesity and IR in adolescents [6]. Accordingly, detailed analysis of FA subtypes can provide valuable information in management of dietary intake or supplementation of FAs, which are deficient in adolescents with obesity and IR. In conclusion, using current diagnostic methods with high sensitivity and specificity will provide more reliable results.
http://dx.doi.org/10.1016/j.steroids.2014.10.006 0039-128X/Ó 2014 Elsevier Inc. All rights reserved.
Conflict of interest The authors state that there is no conflict of interests regarding the publication of this paper. References [1] Ortega L, Garcia-Anguita A, Riestra P, Ortega H, Soriano-Guillén L, Lasunción MA, et al. Plasma non-esterified fatty acid levels in children and their relationship with sex steroids. Steroids 2014;88:15–8. [2] Ankarberg-Lindgren C, Norjavaara E. A purification step prior to commercial sensitive immunoassay is necessary to achieve clinical usefulness when quantifying serum 17b-estradiol in prepubertal children. Eur J Endocrinol 2008;158:117–24. [3] Stanczyk FZ, Lee JS, Santen RJ. Standardization of steroid hormone assays: why, how, and when? Cancer Epidemiol Biomarkers Prev 2007;16:1713–9. [4] Han LD, Xia JF, Liang QL, Wang Y, Wang YM, Hu P, et al. Plasma esterified and non-esterified fatty acids metabolic profiling using gas chromatography–mass spectrometry and its application in the study of diabetic mellitus and diabetic nephropathy. Anal Chim Acta 2011;689:85–91. [5] Trufelli H, Famiglini G, Termopoli V, Cappiello A. Profiling of non-esterified fatty acids in human plasma using liquid chromatography-electron ionization mass spectrometry. Anal Bioanal Chem 2011;400:2933–41. [6] Gunes O, Tascilar E, Sertoglu E, Tas A, Serdar MA, Kaya G, et al. Associations between erythrocyte membrane fatty acid compositions and insulin resistance in obese adolescents. Chem Phys Lipids 2014. http://dx.doi.org/10.1016/ j.chemphyslip.2014.09.006. pii: S0009-3084(14)00120-0 [Epub ahead of print].
⇑
Erdim Sertoglu Ankara Mevki Military Hospital, Anittepe Dispensary, Biochemistry Laboratory, Ankara, Turkey ⇑ Tel.: +90 507 140 3616; fax: +90 312 304 3300. E-mail address: [email protected] Metin Uyanik Corlu Military Hospital, Biochemistry Laboratory, Tekirdag, Turkey Huseyin Kayadibi Adana Military Hospital, Biochemistry Laboratory, Adana, Turkey Serkan Tapan Gulhane School of Medicine, Department of Medical Biochemistry, Ankara, Turkey Available online 20 November 2014