Congenital Hypothyroidism: Clinical and Laboratory Characteristics in Infants Detected by Neonatal Screening

Abstract

A pilot cord serum thyroid-stimulating hormone (TSH) screening program for congenital hypothyroidism began in December 1988 at the Ministry of Health Maternity Hospitals in Riyadh. Out of 40,000 infants screened, 15 infants with congenital hypothyroidism have been detected. Of these, five had athyreosis, eight with ectopic thyroid glands, interestingly five of which had positive perchlorate discharge test suggestive of organification defects, and two had normally located glands with a perchlorate discharge test suggestive of organification defects. The female to male ratio was 1.5:1. The clinical characteristics in our cases were not different from that previously reported. Although there was no significant difference in the mean cord T4 values among the different groups, the mean T4 values at recall in the aplastic group is significantly (P < 0.001) lower than the cord results (60.3 versus 15.3) and that is of recall for the ectopic group (15.3 versus 47.0). There was no significant difference in the mean TSH among the different groups in the cord and recall samples. The skeletal maturation was more delayed in the athyrotic group. The mean age at the time of recall was 17.8 days (range 6 to 64) and the mean age at the start of therapy was 20 days (range 8 to 64).

Neonatal Screening for Congenital Hypothyroidism in Riyadh: Analysis of Six Years' Experience

“…1,6,13,14,19 In accordance with other reports, thyroid ectopy was the most common. 11,13,[18][19][20] Furthermore, the finding of a high percentage (26%) of patients with normally located glands and high uptake, which suggests dyshormonogenesis, confirms the previous observation of the high incidence in this part of the world. 5,6,18,21 This is due to the high frequency of consanguinity among our population.…”

“…11,13,[18][19][20] Furthermore, the finding of a high percentage (26%) of patients with normally located glands and high uptake, which suggests dyshormonogenesis, confirms the previous observation of the high incidence in this part of the world. 5,6,18,21 This is due to the high frequency of consanguinity among our population. The mean age of 17.8 days (range 5 to 64) for the start of therapy would appear to be longer than desirable for a newborn screening program.…”

“…As in other studies, clinical signs of hypothyroidism were absent in the majority of our patients and were more obvious in patients with thyroid aplasia 10,11,13,14,18 Therefore, it is apparent that although many infants with aplasia of the thyroid will be detected within the first few weeks of life, on the basis of clinical history and examination, many cases will be missed, especially infants with ectopic glands, as they have some residual tissue that is capable of producing thyroxine in amounts that mask the clinical symptoms and delay the diagnosis. This is supported by the biochemical values of TSH and T 4 in our series (Table 4).…”