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Effect of repeated freezing and thawing on vitamins and hormones in serum.

Effect of repeated freezing and thawing on vitamins and hormones in serum. No. of fr.ezlng and thawing cycles before essay Analyt. Two Thre. Four 491 (37) 40 (7) 1086 (239) Nutrients Retinol, 1zg/L Retinol-binding protein, 494 (41) 39 (5) 1071 (138) 244 (42) 443(64) 492 (44) 40 (3) 1085 (172) mg/L Total carotenoids, /L Beta-carotene, p/L Lycopene, pg/L Total tocopherol, mg/L Hormones Testosterone, ng/L 244 (42) 443(42) 239 (35) 453(65) 8.0 (0.9) 3045(339) 378 (35) 5.4 (0.4) 15.8(0.5) 7.9 (0.4) 8.0(0.5) 3106(159) 389 (22) 5.9 (0.4) 15.1 (0.4) 8.5 (0.4) 7.9 (0.5) Dihydrotestosterone, ng/L Prolactin, j.g/L Lutropin,mt. units/L Follitropin, t. units/L m Effect of Repeated Freezing and Thawing on Vitamins and Hormones in Serum, Ann W. Hsing,1 George W. Com8tock,2 and B. Frank PoW (1 Dept. of Epidemiology, School of Hygiene and Public Health, The Johns Hopkins University, Baltimore, MD 21205; present address: Epidemiology and Biostatistics Program, Division of Cancer Etiology, National Cancer Institute, Executive Plaza North, Rockville, MD 20892; 2 address correspondence to this author at Johns Hopkins Training Center for Public Health Research, Box 2067, Hagerstown, MD 21742-2067; 3deceased) Increasing numbers of studies are comparing the prediagnostic concentrations of biochemical markers in sera from persons subsequently diagnosed as having cancer and in persons not known to have cancer (1). Sera may be used for more than a single study and undergo repeated freezing and thawing. Several studies have investigated the effects of such treatment on vitamin A (2-4); vitamin E (5); ta-carotene (6); thyroxin, cortisol, and insulin (7); and testosterone and androstenedione (8). To add to this information, we undertook a small study of the effects of repeated freezing and thawing on serum concentrations of retinol, carotenoids, and tocopherol, and on testosterone, dthydrotestosterone, prolactin, lutropin, and foffitropin. Sera from healthy volunteers were pooled, mixed thoroughly, pipetted into 3.6-mL Cryotubes (Nunc, Roskilde, Denmark), and stored at -73 #{176}C. Enough of these aliquots were thawed to yield 15 1-mL aliquots for vitamin assays after two, three, and four freeze-thaw cycles and five 2-mL aliquots for hormone assays after two and three freezethaw cycles. Hormones were assayed by Hazleton Laboratories, Vienna, VA; vitamins were assayed by our laboratory. To remove the effects of any day-to-day laboratory variations, Repeated freezing and thawing appears unlikely to affect the concentrations of retinol, retinol-binding protein, carotenoids, and tocopherol in serum. Unfortunately, the number of assays for hormones is too small to allow any conclusion other than that the effects of freezing and thawing are not likely to be catastrophic. Nonetheless, for long-term studies, it still seems desirable to store sera in several small aliquots to obviate repeated freezing and thawing. This work was supported in part by Cancer Training Grant T32CA09314 and research grant CA 36390 from the National Cancer Institute, and Career Research Award ML 21670 from the National Heart, Lung, and Blood Institute. We thank Marie A. Foard for help with the vitamin assays. References 1. Petrakis NL. Biologicbanking in cohort studies,with special reference to blood. In: Garfinkel L, Ochs 0, Mushineki M, eda. Selection,follow-upand analysisin prospectivestudies:workshop. NatlCancerInst Monogr 67.NIH Pub. No. 85-2713. Washington: U.S. Govt. Printing Office, 1985:193-8. 2. Driskell WJ, Lackey AD, Hewett JS, Bashor MM. Stability of vitamin A in frozen sera. Cliii Chem 1985;31:871-2. 3. Driskell WJ, Bashor MM, Neeae JW. Loss of vitamin A in long-term stored, frozen sara. Chin Chim Acta 1985;147:25-30. 4. Driskell WJ, Neese JW, Bryant CC, Bashor MM. Measurement of vitamin A and vitamin E in human serum by high performance liquid chromatography. J Chromatogr 1982;231:439-44. 5. Gunter EW, Driskell WJ, Yeager PR. Stability of vitamin E in long-term stored serum. Cliii Chim Acta 1988;175:329-36. 6. Nierenberg DW. Serum and plasma fl-carotene levels measured with an improved method of high-performance liquid chroniatography. J Chromatogr 1985;339:273-84. 7. Reimers TJ, McMann JP, Cowan RG, et al. Effects storage, of hemolysis, and freezing and thawing on concentrations of thyroxun, cortisol, and insulin in blood samples. Proc Soc Exp Biol Med 1982;170:509-16. 8. Wickings JE, Nieschlag E. Stability of testosterone and androstenedione in blood and plasma samples. Chin Chim Acta 1976;71:439-43. CLINICAL CHEMISTRY, Vol. 35,No.10,1989 2145 http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Clinical Chemistry American Association for Clinical Chemistry

Effect of repeated freezing and thawing on vitamins and hormones in serum.

Clinical Chemistry , Volume 35 (10): 2145 – Oct 1, 1989

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American Association for Clinical Chemistry
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Copyright © 1989 by the American Association for Clinical Chemistry.
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0009-9147
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Abstract

No. of fr.ezlng and thawing cycles before essay Analyt. Two Thre. Four 491 (37) 40 (7) 1086 (239) Nutrients Retinol, 1zg/L Retinol-binding protein, 494 (41) 39 (5) 1071 (138) 244 (42) 443(64) 492 (44) 40 (3) 1085 (172) mg/L Total carotenoids, /L Beta-carotene, p/L Lycopene, pg/L Total tocopherol, mg/L Hormones Testosterone, ng/L 244 (42) 443(42) 239 (35) 453(65) 8.0 (0.9) 3045(339) 378 (35) 5.4 (0.4) 15.8(0.5) 7.9 (0.4) 8.0(0.5) 3106(159) 389 (22) 5.9 (0.4) 15.1 (0.4) 8.5 (0.4) 7.9 (0.5) Dihydrotestosterone, ng/L Prolactin, j.g/L Lutropin,mt. units/L Follitropin, t. units/L m Effect of Repeated Freezing and Thawing on Vitamins and Hormones in Serum, Ann W. Hsing,1 George W. Com8tock,2 and B. Frank PoW (1 Dept. of Epidemiology, School of Hygiene and Public Health, The Johns Hopkins University, Baltimore, MD 21205; present address: Epidemiology and Biostatistics Program, Division of Cancer Etiology, National Cancer Institute, Executive Plaza North, Rockville, MD 20892; 2 address correspondence to this author at Johns Hopkins Training Center for Public Health Research, Box 2067, Hagerstown, MD 21742-2067; 3deceased) Increasing numbers of studies are comparing the prediagnostic concentrations of biochemical markers in sera from persons subsequently diagnosed as having cancer and in persons not known to have cancer (1). Sera may be used for more than a single study and undergo repeated freezing and thawing. Several studies have investigated the effects of such treatment on vitamin A (2-4); vitamin E (5); ta-carotene (6); thyroxin, cortisol, and insulin (7); and testosterone and androstenedione (8). To add to this information, we undertook a small study of the effects of repeated freezing and thawing on serum concentrations of retinol, carotenoids, and tocopherol, and on testosterone, dthydrotestosterone, prolactin, lutropin, and foffitropin. Sera from healthy volunteers were pooled, mixed thoroughly, pipetted into 3.6-mL Cryotubes (Nunc, Roskilde, Denmark), and stored at -73 #{176}C. Enough of these aliquots were thawed to yield 15 1-mL aliquots for vitamin assays after two, three, and four freeze-thaw cycles and five 2-mL aliquots for hormone assays after two and three freezethaw cycles. Hormones were assayed by Hazleton Laboratories, Vienna, VA; vitamins were assayed by our laboratory. To remove the effects of any day-to-day laboratory variations, Repeated freezing and thawing appears unlikely to affect the concentrations of retinol, retinol-binding protein, carotenoids, and tocopherol in serum. Unfortunately, the number of assays for hormones is too small to allow any conclusion other than that the effects of freezing and thawing are not likely to be catastrophic. Nonetheless, for long-term studies, it still seems desirable to store sera in several small aliquots to obviate repeated freezing and thawing. This work was supported in part by Cancer Training Grant T32CA09314 and research grant CA 36390 from the National Cancer Institute, and Career Research Award ML 21670 from the National Heart, Lung, and Blood Institute. We thank Marie A. Foard for help with the vitamin assays. References 1. Petrakis NL. Biologicbanking in cohort studies,with special reference to blood. In: Garfinkel L, Ochs 0, Mushineki M, eda. Selection,follow-upand analysisin prospectivestudies:workshop. NatlCancerInst Monogr 67.NIH Pub. No. 85-2713. Washington: U.S. Govt. Printing Office, 1985:193-8. 2. Driskell WJ, Lackey AD, Hewett JS, Bashor MM. Stability of vitamin A in frozen sera. Cliii Chem 1985;31:871-2. 3. Driskell WJ, Bashor MM, Neeae JW. Loss of vitamin A in long-term stored, frozen sara. Chin Chim Acta 1985;147:25-30. 4. Driskell WJ, Neese JW, Bryant CC, Bashor MM. Measurement of vitamin A and vitamin E in human serum by high performance liquid chromatography. J Chromatogr 1982;231:439-44. 5. Gunter EW, Driskell WJ, Yeager PR. Stability of vitamin E in long-term stored serum. Cliii Chim Acta 1988;175:329-36. 6. Nierenberg DW. Serum and plasma fl-carotene levels measured with an improved method of high-performance liquid chroniatography. J Chromatogr 1985;339:273-84. 7. Reimers TJ, McMann JP, Cowan RG, et al. Effects storage, of hemolysis, and freezing and thawing on concentrations of thyroxun, cortisol, and insulin in blood samples. Proc Soc Exp Biol Med 1982;170:509-16. 8. Wickings JE, Nieschlag E. Stability of testosterone and androstenedione in blood and plasma samples. Chin Chim Acta 1976;71:439-43. CLINICAL CHEMISTRY, Vol. 35,No.10,1989 2145

Journal

Clinical ChemistryAmerican Association for Clinical Chemistry

Published: Oct 1, 1989

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