Outcome for congenital hypothyroidism.

Abstract

SUMMARY In a study designed to provide retrospective control data for a neonatal thyroid screening programme, the problems of 141 hypothyroid children were examined. The mean IQ (Weschler intelligence scale) was 79-5 for children with congenital hypothyroidism but was normal in 6 children diagnosed before age 6 weeks. Diagnostic delay was associated with a steady decline in mean IQ but there was an improvement in some late diagnosed cases. A strong association was found between IQ and parental social class. Twenty five percent of the children were mentally retarded and 29% were at special schools; 54% of children at normal schools and 43% at special schools showed deviant behaviour. Other problems included clumsiness (26-2%) and squints (26-2%), and these were more common in children with a lower IQ. Congenital hypothyroidism is associated with persistent morbidity in many aspects of cerebral function. The adverse effects of prenatal hypothyroidism are largely reversible if treated before age 6 weeks.Neonatal screening for congenital hypothyroidism (CH) has been progressively introduced throughout North America, Japan, and Europe over the past five years and is now also universal in the United Kingdom. In none of these screening programmes has it been considered ethical to conduct any controlled trial of the value of screening itself. Thus the assessment of the results depends in part on comparison with retrospective studies of children with clinically diagnosed CH. Because previous retrospective studies had shown an improvement in mean IQ with earlier diagnosis,' 2 screening was expected to be effective in preventing mental retardation and reversing the effects of intrauterine hypothyroidism. Some doubts were, however, expressed by McFaul et al.3 as to whether screening would be fully effective in preventing all the long term complications of CH. In particular they found that some children diagnosed between 4 and 10 weeks of age had evidence of clumsiness, visual disorders, learning difficulties, and behaviour problems. The present study was undertaken to see if these findings were representative of an unselected group of children with CH and also to provide up to date retrospective data for comparison with children diagnosed by screening. Patients and methodsAltogether 141 hypothyroid children were included in the study. The names of 98 children were obtained by writing to all the paediatricians in the four Thames health regions. To ensure that other handicapped hypothyroid children were not missed, the 21 area health authorities in these regions were asked to supply the names of children with CH from the handicap registers, and this produced 41 more children. Two children were found who were in long stay mental hospitals. While the handicap registers gave the names of only 4 children who were not seeing a paediatrician regularly, they helped considerably in tracing children who were attending hospital clinics.Data on the mode of presentation and confirmatory tests were obtained from the case notes.

Useful Parameters To Predict the Eventual Mental Outcome of Hypothyroid Children

“…Even though the more affected patients might be slightly delayed in development, they reach better scores than those reported for nonscreened infants with CH. Hulse (20) reported a mean I.Q. of 79.5 for 99 children with CH diagnosed before screening and evaluated with the W.I.S.C.R.…”

ENDOCRINOLOGY AND ADOLESCENCE: Congenital hypothyroidism: a clinical update of long-term outcome in young adults

“…In series of patients studied before the introduction of neonatal screening, major differences in clinical characteristics were found between patients with different degrees of intellectual disability (15,16,17,18) and about one-quarter of children with clinically diagnosed CH have overt neurodevelopmental deficits (19).…”

Initial catch-up growth in children with hypothyroidism on thyroxine replacement therapy

“…[9][10][11][12] Before the neonatal screening was initiated in the 1970s, the percentage of children with congenital hypothyroidism (CH) having a height below the 10 th percentile has been shown to range from 19% to 31%. 13 Adult stature without treatment ranged from 1 to 1.6 metres, depending on severity, gender and other genetic factors. 13 Growth data were available for 36 patients in our study The growth velocity in the short-term was robust at 7.7 cm/year, which was higher than that seen at any period of childhood after the initial two years of life, excepting the pubertal growth spurt.…”

“…13 Adult stature without treatment ranged from 1 to 1.6 metres, depending on severity, gender and other genetic factors. 13 Growth data were available for 36 patients in our study The growth velocity in the short-term was robust at 7.7 cm/year, which was higher than that seen at any period of childhood after the initial two years of life, excepting the pubertal growth spurt. This increased velocity accounted for a partial catch-up growth with a height gain of 0.42 SDS in the whole group over merely 14.1±2.5 months of thyroxin replacement.…”