[Serum TSH values during clinical controls of patients treated for congenital hypothyroidism]

During the second half of 1995, an increased serum TSH level was found in about 50% of the patients that had been biochemically studied to check their treatment for hypothyroidism by the Laboratory of Molecular Endocrinology in the Regional Hospital of Malaga. A retrospective analysis was carried out to check if those results were erroneous. The biochemical data concerning the thyroid function were followed-up in patients requiring more studies, such as the ones suffering from congenital hypothyroidism (CH) and a random double assay of some samples was made with an alternative technique. Currently, the average TSH level is rated as 14.31 microU/ml in 54% of the subjects, even though levothyroxine doses were increased. Levothroid is the preparation prescribed in all cases. In 1994, the TSH average level was 1.68 microU/ml in the aforementioned group. Another 12% with increased TSH levels were readjusted by modifying the treatment. The T4F in CH subjects with increased TSH dropped significantly from 24.1 pmol/ml to 15.7 pmol/ml in the same period of time. We suggest that one possible etiological factor could be a mistake in the dosage of the commercial preparation.