Congenital hypothyroidism: etiology

The etiology of congenital hypothyroidism (CH) is important in determining its severity, prognosis, genetic counseling and clinical management.

AIMS

investigate the causes of CH and their severity using serum levels of FreeT4 and TSH.

PATIENTS AND METHODS

243 neonates with CH (61% were girls) diagnosed by the Neonatal Screening Program of Minas Gerais between 1996 and 2003. The thyroid function was assessed through serum FreeT4 and TSH by chemilumiscence. CH etiology was evaluated by ultrasonography, scintigraphy, potassium perchlorate discharge test and serum thyroglobulin levels.

RESULTS

Out of 243 patients, dysgenesis was found in 114 (47%): 3.3% had athyreosis; 0.4% eutopic dysgenetic gland due to maternal use of 131I; 22% ectopic glands (8.6% an isolated ectopic gland and 13% also an eutopic dysgenetic thyroid); 9% eutopic dysgenesis, 8.6% hypoplasia and 3.7% hemiagenesis. Thyroid in situ was found in 129 (52%): 23.5% had iodide organification defect; 3.7% thyroglobulin synthesis defect; 6.2% other 0.4% dyshomonogenesis; iodide transport defect; 1.2% transient CH and 18% a normal gland. Patients with dysgenesis had a more severe CH than those with thyroid in situ (TSH 248.08 vs. 18.17 microIU/mL and FT4 0.32 vs. 0.95 ng/dL, p < 0.001).

CONCLUSIONS

Some cases had more complex dysgenesis, presenting ectopia associated to a dysgenetic eutopic gland. The ultrasound was the best tool to detect the dysgenetic tissue, but the scintigraphy was the most effective in identifying the functioning tissue. The thyroid hormone synthesis defects were found more frequently than expected, but in some cases they could not be defined.

Screening for congenital hypothyroidism in extreme premature and/or very low birth weight newborns: the importance of a specific protocol

BACKGROUND

Neonatal screening for congenital hypothyroidism (CH) in premature infants is not as well established as in term newborns regarding age and number of samples.

AIMS

1. To evaluate the effectiveness of the protocol recommended by the Neonatal Screening Program of the State of Minas Gerais (PETN-MG) for CH neonatal screening in very low birth weight premature infants. 2. To estimate the prevalence of delayed TSH elevation and thyroid function alterations in the target population.

METHODS

TSH was assessed by ELISA on the 5th, 10th and 30th days of life in all newborns with gestational age <32 weeks and/or very low birth weight (VLB) (<1,500 g) in the period from October 2004 to September 2006.

RESULTS

Out of the 14,462 newborns screened, 2,647 were premature with gestational age <32 weeks and/or VLB. Forty-four cases of altered TSH were found and 11 infants underwent treatment. Delayed TSH elevation was detected in 66% of altered cases. Five out of the 11 cases were detected in the second sample and five cases were only detected in the third sample.

CONCLUSION

The high prevalence of thyroid function alterations that demanded treatment (1:242) and delayed TSH elevation in VLB premature infants reinforce the need for a specific protocol, based on retesting procedures, for CH neonatal screening.

[Study of intestinal malabsorption diseases as cause of monosymptomatic short stature]

OBJECTIVE: This study was carried out in order to evaluate the etiology of monosymptomatic childhood short stature (below the third percentile or with growth rate of less than 5 cm/year) with emphasis on causes due to intestinal malabsorption. METHODS: Each patient was submitted to endocrinological, biochemical and hematological investigation. Determination of serum anti-gliadin antibodies, fecal fat, chloride levels in sweat, jejunal biopsy and bone age was also obtained.RESULTS: A total of 51 children was studied, most of them belonging to the group of normal variants. Four children had abnormally high sweat chloride, compatible with the diagnosis of cystic fibrosis. These children were asymptomatic regarding respiratory and gastrointestinal tract. CONCLUSIONS: We conclude that cystic fibrosis, besides celiac disease, must be included in the differential diagnosis of short stature in childhood.

[Human chorionic gonadotropin: a feasible option for treating undescended testes]

In order to shed light on the controversy in the literature about the efficacy of medical treatment of undescended testes, HCG was administered to 73 boys. They were seven month to twelve years old and none of them had puberty signs. Cryptorchidism was unilateral in 75.4%; it was bilateral in 24.6%. Children with retractile testes were excluded from the study. The patients received IM HCG 1500 to 2000 IU/sqm twice a week for 5 weeks. Testicular descent was noted in 23.0% of the undescended testes, often in the first 2.5 weeks of therapy. All children were followed up for at least a year and relapse was observed in 8.3%. Clinical signs of testosterone action faded off shortly after the end of injections. No side effects were apparent by the third month after treatment. We conclude that the administration of HCG is worth of a trial before the surgical approach is contemplated in the management of the cryptorchidism.

Morning steroid profile in children with congenital adrenal hyperplasia under different hydrocortisone schedules

We studied 13 children with 21-hydroxyalse deficiency to explore the immediate potential suppressive effect of hydrocortisone dose schedule on the adrenal cortex. They were given 20 mg/m2 daily in a controlled trial. After random administration of a greater dose in the morning (7 patients) or at night (6 patients), we measured plasma levels of 17-hydroxyprogesterone, testosterone, and androstenedione at times-24, 0, 2, 4, and 6h. Considerable fluctuation of the steroid levels, unrelated to the drug intake, was observed. There was no statistically significant differences between the "morning dose" and "night dose" groups for any steroid. We conclude that; (i) the greater night dose did not avoid the 17-hydroxyprogesterone morning peaks, and (ii) the variation in plasma steroid levels is so marked that a single morning sample is unreliable to reflect the degree of adrenal suppression.