Inter-laboratory validation of the measurement of follicle stimulating hormone (FSH) after various lengths of frozen sto
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RESEARCH
Open Access
Inter-laboratory validation of the measurement of follicle stimulating hormone (FSH) after various lengths of frozen storage Jessica Scriver1, Valerie L Baker2, Steven L Young3, Barry Behr2, Lisa M Pastore4*
Abstract Background: Serum follicle stimulating hormone (FSH) levels are used clinically to evaluate infertility, pituitary and gonadal disorders. With increased frequency of research collaborations across institutions, it is essential that interlaboratory validation is addressed. Methods: An inter-laboratory validation of three commercial FSH immunoassays was performed with human serum samples of varying frozen storage length (2 batches of 15 samples each) at -25 degree C. Percentage differences and Bland-Altman limits of agreement were calculated. Results: The inter- and intra-laboratory consistency of FSH values with the same assay manufacturer was much higher after shorter-term storage (frozen for less than 11 months, mean percentage degradation less than 4%) than after long-term storage (2-3 years, mean percentage degradation = 23%). Comparing assay results from different manufacturers, there was similar overall long term degradation as seen with the same manufacturer (-25%), however the degradation was greater when the original FSH was greater than 20 mIU/mL relative to less than 10 mIU/mL (p < 0.001 trend test). Conclusion: The findings suggest that degradation of serum samples stored between 11 months and 2-3 years at -25 degrees C can lead to unstable FSH measurements. Inter-laboratory variability due to frozen storage time and manufacturer differences in assay results should be accounted for when designing and implementing research or clinical quality control activities involving serum FSH at multiple study sites.
Background Follicle-stimulating hormone (FSH) is a glycoprotein dimer secreted by the adenohypophysis that stimulates gametogenesis. Because serum FSH levels provide insight into the functional capacity of the hypothalamus, pituitary, and ovary or testis, they are frequently used for clinical evaluation of infertility, and disorders of the hypothalamic-pituitary-gonadal axis [1]. Specifically, FSH levels can be used to evaluate the etiology of low sperm counts, amenorrhea, menstrual irregularities, pituitary disorders, precocious or delayed puberty, and ovarian/testicular dysfunction [2,3]. Clinical determination of FSH concentration is typically measured in the serum, while measurement of * Correspondence: [email protected] 4 OB/GYN Department, University of Virginia, Charlottesville, VA 22908-0712, USA Full list of author information is available at the end of the article
urine FSH levels has replaced those in serum for some research protocols to avoid venipuncture. The correlation between urine and serum FSH values ranges from 70% - 90% [4]. Stability of stored FSH samples has been evaluated primarily in urine, with optimal storage conditions for sustained FSH immunoreactivity determined to be 1-4 weeks at 4°C due to significant degradation after 4 weeks [5].
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