Commentary on: Use of Microsphere Immunoassay for Simplified Multianalyte Screening of Thyrotropin and Thyroxine in Dried Blood Spots from Newborns

riod. All showed increased TSH (43– 235 mIU/L). Four showed clearly decreased T4 [1.2–23.8 nmol/L (0.1– 1.85 g/dL)]. Another two had T4 concentrations below our cutoff of 30.8 nmol/L (2.4 g/dL), and only one had a T4 concentration within the reference interval [67 nmol/L (5.2 g/dL)]. This is in agreement with literature data that 10–20% of all CH cases with increased TSH concentrations are not accompanied by low T4 (1 ). Interestingly, the ratio of TSH to T4 was an excellent indicator for CH in neonates because deviations in TSH as well as T4 values will yield highly increased ratios of TSH to T4. For healthy newborns, we observed ratios of 0–4, whereas our seven patients as well as abnormal controls showed values 20. In summary, our modified multianalyte assay for TSH and T4 simplifies the analytical protocol of the procedure to allow easier handling and more rapid analysis. Furthermore, future automation of the process becomes an option, which is indispensable for the high-throughput screening usually required in all larger screening laboratories. LabMap technology provides an alternative to mass spectrometry for the simultaneous analysis of metabolites present in samples at very low concentrations. Other endocrinologic metabolites, e.g., 17-hydroxyprogesterone, a marker for congenital adrenal hyperplasia, can also be incorporated in the analytical protocol. This would allow the simultaneous analysis of all endocrinologically relevant metabolites for newborn screening in one analytical run.