A thyroxine dosage of 8 μg/kg per day is appropriate for the initial treatment of the majority of infants with congenital hypothyroidism

Abstract

Even though a subgroup of patients may require a higher dosage of L-thyroxine, an initial dosage of 7.5-8.0 micrograms/kg per day, with an early assessment of FT4, FT3, and TSH levels, is adequate for the treatment of the majority of infants with congenital hypothyroidism.

Adult Height in Congenital Hypothyroidism: Prognostic Factors and the Importance of Compliance with Treatment

“…It has been argued that a delay in treatment could induce a loss in the potential of growth of the epiphyseal cartilage [18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28], which would agree with our findings. However, this should have no consequences nowadays as treatment is started much earlier.…”

“…5 and 12 years, puberty-related factors and treatment between 12 and 15 years were studied. Initial doses of LT4 have been largely studied elsewhere [7, 20, 21, 22, 23]and will not be mentioned further in this study.…”

Suppression of TSH in Congenital Hypothyroidism Is Significantly Related to Serum Levels and Dosage of Thyroxine

“…Some authors [8]maintain that early normalization of serum T 4 levels, independent of the corresponding TSH concentrations, is a satisfactory treatment goal, whereas others [11, 12]have emphasized that the TSH level is the only biological marker of adequacy of tissue levels of T 4 , particularly in the brain. Proponents of management based on T 4 levels alone raise concerns about short-term side effects of overtreatment [8]and long-term neuropsychological sequelae [13], such as poor concentration with larger doses of T 4 .…”

“…Some studies suggest that an elevated TSH concentration is related to undertreatment only [9, 12, 14, 15], whereas other studies [8, 20, 25, 26]see an important role for variable maturation of the pituitary threshold for TSH release. Delayed maturation should only be implicated if TSH concentrations remain elevated despite appropriate T 4 replacement and T 4 levels in the upper range of normal [9].…”

Congenital hypothyroidism: treat children but don't forget their parents

“…Depending on the initial dose of L-T 4 , neonatal serum T 4 and thyrotrophin (TSH) levels may take several weeks to rise to the normal range. In the US (20) higher starting doses of L-T 4 (10-15 mg/kg per day) have been used to treat children with CH than in Europe (5,16,21) and have been associated with a shorter time to achieve euthyroidism. The Quebec group (9) reported that infants with severe CH, defined by low serum T 4 levels and retarded skeletal maturation, who had been treated with an initial dose of L-T 4 of 6 mg/kg per day beginning at a mean age of 5 weeks had a mean IQ at the age of 12 years that was 15 points lower than that of infants with less severe CH.…”