The need for standardized bloodspot TSH-calibrators in congenital hypothyroidism screening.
BACKGROUND
The preparation of bloodspot calibrators and quality control samples for neonatal thyrotropin (TSH), as part of the national quality assessment scheme in The Netherlands, is sometimes problematic. Often, the recovery of the added TSH is well above 100% when measured in plasma. Results from other External Quality Assessment Schemes for neonatal TSH show similar problems.


RESULTS
A questionnaire was sent to 17 kit manufacturers and organizers of EQAS concerning the preparation of bloodspot calibrators for TSH; 13 completed questionnaires were returned. There are large differences with respect to type of filterpaper, matrix, assessment of TSH-concentrations to the calibrators, size of the bloodspots, shelf life, etc.


CONCLUSIONS
Attention is focused on several items to be considered when attempting standardization of the preparation of TSH bloodspot calibrators.
Elvers
L H
LH
Diagnostic Laboratory for Infectious Diseases and Perinatal Screening, National Institute of Public Health and the Environment, Bilthoven, The Netherlands.
Loeber
J G
JG
D003409:Congenital Hypothyroidism; D004355:Drug Stability; D006801:Humans; D007037:Hypothyroidism / Q000097:blood; D007231:Infant, Newborn; D015997:Neonatal Screening / Q000592:standards*; D010209:Paper; D011786:Quality Control; D011933:Reagent Kits, Diagnostic; D011795:Surveys and Questionnaires; D013696:Temperature; D013972:Thyrotropin / Q000097:blood*
D011933:Reagent Kits, Diagnostic; D013972:Thyrotropin