RT Journal Article
SR Electronic
T1 Paediatric reference interval and biological variation trends of thyrotropin (TSH) and free thyroxine (T4) in an Asian population
JF Journal of Clinical Pathology
JO J Clin Pathol
FD BMJ Publishing Group Ltd and Association of Clinical Pathologists
SP 642
OP 647
DO 10.1136/jclinpath-2015-202916
VO 68
IS 8
A1 Tze Ping Loh
A1 Sunil Kumar Sethi
A1 Michael Patrick Metz
YR 2015
UL http://jcp.bmj.com/content/68/8/642.abstract
AB Aims To describe the reference intervals and biological variation data for thyrotropin (TSH) and free thyroxine (FT4) in a mixed Asian population using an indirect sampling approach and to compare them with published reports.Methods TSH and FT4 of children measured once or twice over a 7-year period (2008–2014) at primary-care and tertiary-care settings were extracted from the laboratory information system. After excluding outliers, age-related reference intervals were derived using the Lambda-Mu-Sigma (LMS) approach, while age-partitioned biological variation data were obtained according to recommendations by Fraser and Harris.Results Both TSH and FT4 were very high at birth and declined with age. Similarly within-individual and between-individual biological variations were higher for both TSH and FT4 at birth and also declined with age. Our data were broadly similar to previous studies. Significant heterogeneity in study population and methods prohibited direct numerical comparison between this and previously published studies.Conclusions This study fills two important gaps in our knowledge of paediatric thyroid function by reporting the centile trends (and reference values) in a mixed Asian population, as well as providing age-partitioned biological variation data. The variation in published reference intervals highlights the difficulty in harmonising paediatric thyroid reference intervals or recommending universal clinical cut-offs.