[The therapy of congenital hypothyroidism]

In congenital hypothyroidism precocious diagnosis and consequent replacement therapy are necessary to prevent neurological irreversible damage caused by postnatal thyroid hormone deficiency. Synthetic L-thyroxine is the useful drug, that has to be administered in fasting condition to have the best absorption. Some points about the treatment are still discussed, such initial L-thyroxine dosage, biochemical control parameters and psycho-intellectual outcome in treated patients. The mean initial dosage in Italy increased from 7.5 +/- 2.2 micrograms/kg/day in 1987-90 period to 8.5 +/- 2.5 micrograms/kg/day in 1991, at a mean starting age of 34 and 26 days respectively. Therefore the dosage is modulated on the basis of serum levels of thyroid hormones and clinical signs. Some patients, in spite of a correct dosage of L-thyroxine, show a deficient suppression of TSH circulating level. In our experience this finding is sometimes due to the non-observance of the fasting condition when the drug is administered. Patients precociously identified by neonatal screening and correctly treated have a good mental and statural prognosis. In these patients, the psycho-intellectual development is better than in those diagnosed later clinically.