High-sensitive detection and quantitation of thyroid-stimulating hormone (TSH) from capillary/fingerstick and venepuncture whole-blood using fluorescence-based rapid lateral flow immunoassay (LFIA)

Newborn screening for primary congenital hypothyroidism: past, present and future

This manuscript reviews the evolution of newborn screening for primary congenital hypothyroidism (CH) and explores future strategies to enhance diagnostic accuracy. Over the past few decades, newborn screening has expanded globally, significantly reducing the incidence of severe forms of the disease. However, challenges persist, especially regarding the overdiagnosis of mild cases of primary CH, which may not require treatment. Omic sciences may help researchers to enhance the understanding of primary CH and to uncover new biomarkers to identify mild cases with altered proteomic and/or metabolic profiles associated with the need for treatment. Record-linkage studies can help deepen knowledge on the long-term outcomes of affected children identified through newborn screening. Nevertheless, despite 50 years of newborn screening for primary CH, a minority of newborns currently benefit from this critically important public health intervention. Efforts should be done to expand access to newborn screening globally, especially for those born in developing countries.

Determination of Capillary Blood TSH and Free Thyroxine Levels Using Digital Immunoassay

Background

The remote performance of thyroid function blood tests is complicated because it requires blood collection.

Objective

To compare TSH and free thyroxine (FT4) levels between capillary and venous blood and assess the adequacy of measuring each value in capillary blood.

Methods

This prospective intervention study was conducted at Ito Hospital and was based on the clinical research method. The participants were 5 healthy female volunteers and 50 patients (41 females and 9 males) between the ages of 23 and 81 years. To measure TSH and FT4 levels in capillary and venous blood, a digital immunoassay (d-IA) method capable of measuring trace samples was used. Chemiluminescence measurements were used as controls. Values obtained for each assay system were compared using Spearman's correlation analysis. Capillary blood was collected using an autologous device (TAP II; not approved in Japan).

Results

Capillary plasma volume obtained using TAP II was 125 µL or more in 26 cases, 25 µL to 124 µL in 24 cases, and less than 25 µL in 5 cases. Strong correlations were noted in the TSH and FT4 levels between capillary and venous blood, with correlation coefficients of rs = 0.99 and rs = 0.97, respectively.

Conclusion

Capillary TSH and FT4 levels strongly correlate with venous blood values. Trace samples can be used in high-precision d-IA methods. These results may promote telemedicine in assessing thyroid function.