J Clin Pathol Qual Control.  2001 Jun;23(1):215-220.

Recheck Rate, Recall Rate and Reference Range of the Neonatal Screening Test for Congenital Hypothyroidism

• Lee JM
• Choi TY
• Lee DW
• Lee DH

Abstract

BACKGROUND: Recently neonatal mass screening tests on inborn errors of metabolism have been increased rapidly. Enzyme-linked immunosorbent assay(ELISA) as a thyroid stimulating hormone (TSH) test method influenced by variable test condition. Recheck rate and neonatal recall rate secondary to the false positive results can be increased according to the range of reference value.
METHODS
Neonatal screening test for TSH drawn out the capillaries of 22,182 infants' heels requested from March 1995 to August 1999 at the Soonchunhyang University Hospital. The measurement of TSH was performed by ImmuChem N-TSH (ICN Pharmaceuticals Inc., USA) reagent. The recheck rate and recall rate was produced by established reference range (20 micronIU/mL). The correlation between ImmuChem N-TSH and Enzaplate N-TSH (Bayer Diagnostic Ltd., Japan) reagents was evaluated by 50 TSH control samples with low, middle and high concentration. Through two reagents each reference value was analyzed in the 438 newborns requested at screening test since September 1999.
RESULTS
The recheck rate and recall rate of TSH screening test used for ImmuChem N-TSH reagent were 2.16% and 0.93%. The correlation between ImmuChem N-TSH and Enzaplate N-TSH reagents was very good (r=0.996). The 95% reference ranges (mean+/-2SD) of TSH used for two reagents were 0-19.64 micronIU/mL (mean+/-SD = 7.38+/-6.14 micronIU/mL) and 0-14.80 micronIU/mL (mean+/-SD = 4.60+/-5.10 micronIU/mL), respectively. The reference range of TSH was significantly different between two reagents (P<0.001).
CONCLUSIONS
TSH of congenital hypothyroidism had shown a tendency that recheck rate and recall rate are rather higher than that of foreign countries. As the reference range demonstrates different results, it is better to establish an appropriate reference range of each reagent under intensive quality control.

MeSH Terms

Capillaries
Congenital Hypothyroidism*
Heel
Humans
Hypothyroidism
Indicators and Reagents
Infant, Newborn
Mass Screening
Metabolism, Inborn Errors
Neonatal Screening*
Quality Control
Reference Values*
Thyrotropin
Indicators and Reagents
Thyrotropin