Low free thyroxine and normal thyroid-stimulating hormone in infants and children: possible causes and diagnostic work-up

Current status and challenges in establishing reference intervals based on real-world data

Reference intervals (RIs) are the cornerstone for evaluation of test results in clinical practice and are invaluable in judging patient health and making clinical decisions. Establishing RIs based on clinical laboratory data is a branch of real-world data mining research. Compared to the traditional direct method, this indirect approach is highly practical, widely applicable, and low-cost. Improving the accuracy of RIs requires not only the collection of sufficient data and the use of correct statistical methods, but also proper stratification of heterogeneous subpopulations. This includes the establishment of age-specific RIs and taking into account other characteristics of reference individuals. Although there are many studies on establishing RIs by indirect methods, it is still very difficult for laboratories to select appropriate statistical methods due to the lack of formal guidelines. This review describes the application of real-world data and an approach for establishing indirect reference intervals (iRIs). We summarize the processes for establishing iRIs using real-world data and analyze the principle and applicable scope of the indirect method model in detail. Moreover, we compare different methods for constructing growth curves to establish age-specific RIs, in hopes of providing laboratories with a reference for establishing specific iRIs and giving new insight into clinical laboratory RI research. (201 words).

Different combinations of monoclonal antibodies and polyclonal antibodies in the design of neonatal hypothyroidism diagnostic kit

Neonatal hypothyroidism is a deficiency of thyroid hormones at birth that can cause lifelong mental and physical disorders in humans. Lack of timely detection could lead to irreversible damage by neonatal hypothyroidism. However, it could be managed quickly and efficiently via timely diagnosis. The screening programs rely on immunoassays to diagnose neonatal hypothyroidism in most countries. This method is time-consuming, needs laboratory equipment, and should be performed by trained and skilled technicians. Given these circumstances, the ELISA method is not a preferable method for the diagnosing of neonatal hypothyroidism. However, it can be used as a confirmatory method in infants with suspected and unknown neonatal hypothyroidism. In the present study, the homemade SR95-1, SR95-2, and SR95-3 anti-β-TSH polyclonal and the commercially available monoclonal antibodies were used to detect β-TSH in a rapid assay kit design hypothyroidism screening. To design the kit, the different combinations of the antibodies were used to establish a sandwich immune-chromatography method. The designed rapid neonatal hypothyroidism tests were used to measure neonatal β-TSH in 100 dry blood samples. This study showed that the best antibody pair in terms of sensitivity is the SR95-1 antibody as capture antibody and the SR95-2 as a conjugated antibody. Using 100 clinical samples, the designed assay was shown to have 94% sensitivity, 83% specificity, and 94% accuracy. The results showed that polyclonal antibodies (SR95-1 as capture) and SR95-2 (as detector) antibodies can detect the reference range of β-TSH in dried blood samples and can be used in the screening of neonatal hypothyroidism.