Methodologic Limitations on the Measurement of Thyroxine from Small Dried Blood Discs: Comparison of Double-Antibody and Solid Phase Radioimmunoassays
Measuring T4 from the eluate of 10-mm diameter dried blood samples was initially used in screening for neonatal hypothyroidism (Dussault and Laberge 1973; see also related article p. 167ff in this volume). We have previously reported about methodologic factors and limitations involved in using such a technique, involving a dried blood disc 10–13 mm in diameter (Walfish 1975, 1976; Walfish et al. 1975). Using a smaller disc of only 1/8 in. (3.2 mm) in diameter was subsequently proposed (Larsen and Broskin 1975) and has a number of theoretical advantages, as can be seen in Table 1. We therefore developed our own double-antibody radioimmunoassay (MS) to measure T4 in a single 1/8-in. diameter disc and compared our results to a commercial solid phase radioassay (Concept 4, Micromedic System).
KeywordsCongenital Hypothyroidism Mount Sinai Hospital Capillary Blood Sample Solid Phase Assay Solid Phase Radioimmunoassay
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- Walfish PG (1975) Screening for neonatal hypothyroidism using a dried capillary blood method: Observations on methodological factors, selection criteria and preliminary results. In: Fisher DA, Burrow GN (eds) Perinatal thyroid physiology and disease. Raven Press, New York, pp 239–247Google Scholar
- Walfish PG (to be published) Experience with the Toronto regionalized screening program for the detection of neonatal hypothyroidism. In: Fisher DA, Koch R (eds) Newborn screening for hypothyroidism. United States Department of Health, Education and Welfare, Rockville, Md.Google Scholar
- Walfish PG, O’Donnell J, Gelbard A, Pollard A (1973) Clinical application of a radioimmunoassay for thyroxine in unextracted serum: Comparison with a competitive protein binding method (abstract). Clin Res 21:1031aGoogle Scholar
- Walfish PG, O’Donnell J, Ulbright T, Schachter G, Frankl A (1975) Screening for neonatal hypothyroidism: Comparison of neonatal dried capillary blood thyroxine (T4) to cord serum T4 and thyrotropin (TSH). In: Robbins J, Braverman L (eds) Thyroid research. Excerpta Medica, Amsterdam, pp 601–605Google Scholar