versión On-line ISSN 1683-9803
VALENZUELA, Adriana et al. The Reference Value of Thyroid Stimulating Hormone (TSH) Determined by Fluoroimmunoassay in Paraguayan Newborns. Pediatr. (Asunción) [online]. 2011, vol.38, n.2, pp. 101-104. ISSN 1683-9803.
The term “reference values" is widely accepted and applied internationally and can be expressed as the establishment and use of data relevant to the interpretation of medical observations. Thyroid stimulating hormone (TSH) plays a role in early detection of one of the few preventable causes of mental retardation, congenital hypothyroidism. The reference values used in the program for prevention of cystic fibrosis and mental retardation (PPFQRM) were those recommended by the commercial test used (<9 Normal, 9-18 borderline, >18 μU/mL hypothyroidism) using filter paper with blood samples from newborns at 2-6 days of life. We performed a cross-sectional, observational study with 20,168 dried blood samples from full-term newborns at 1-7 days of life to determine the reference value for TSH in the NB population of Paraguay using the measures of central tendency and dispersion: mean, median, percentiles, and frequency distribution in order to describe the variable under study. A TSH of between 0.01--1.0 µU/ml was found in 22% of samples, 1.1-2 µU/ml in 25% of samples, from 2.1--3.0 µU/ml in 19%, between 3.1-4 µU/ml in 12%, from 4.1-5 µU/ml in 8%, and more than 5 µU/ml in 14%. TSH values found were: mean: 2.74, median: 2.22, mode: 0.01, and standard deviation was 2.14 µU/ml. For the 75th percentile: 3.26 µU/ml; 95th: 6.68 µU/ml; and 99th: 9 µU/ml. Based on these observations a cutoff point for TSH was confirmed equivalent to 10 µU/ml.
Palabras llave : Congenital hypothyroidism; reference values; newborn; thyroid stimulating hormone.