Standardization of UMELISA TSH NEONATAL® to 3 mm discs

Abstract

Congenital hypothyroidism (CH), known as one of the most frequent
inherited-metabolic diseases in the world and the cause of avoidable
mental retardation in children, has a worldwide incidence of 1 : 4 000. Developmental
delay and bones maturity is avoided by an early diagnosis and the
beginning of a rapid treatment, obtaining a normal psychomotor development
in children. The availability of assays to determine T4 and thyroid stimulating
hormones (TSH) might be implemented on neonatal screening programs
of congenital hypothyroidism. Immunoassay Center developed the UMELISA
TSH NEONATAL® to determine neonatal TSH levels in dry blood on filter
paper. This assay uses 5 mm discs in samples, standards and control. The number
of diseases to diagnose in Neonatal Screening Programs has increased,
that is why it is necessary the maximum use of samples of blood collected in
filter paper, using 3 mm discs in many assays. The current work shows the
modification performed to UMELISA TSH NEONATAL®. These changes allow
the use of 3 mm discs. The authors obtain precision profiles among 7.0,
10.4 and 96.3 % of relative accuracy. The sensitivity is 1 mUI/L . The modified
assay shows a good linear correlation and accuracy with the UMELISA TSH
NEONATAL® (r = 0.9). That modification does not affect the sensitivity, precision
and accuracy of UMELISA TSH NEONATAL® that is why it can be used
in neonatal screening of congenital hypothyroidism.