In congenital hypothyroidism bone maturation at birth may be a predictive factor of psychomotor development during the first Year of life irrespective of other variables related to treatment.
OBJECTIVE
To evaluate in a cohort of infants with congenital hypothyroidism (CH): (a) the frequency of bone maturation (BM) retardation at birth and (b) whether BM delay at birth may be considered as a tool to make a prognosis of psychomotor status at the age of 1 Year, irrespective of other variables related to treatment.


METHODS
BM at birth, CH severity and developmental quotient (DQ) at the age of 1 Year were retrospectively evaluated in 192 CH infants selected by the following inclusion criteria: (a) gestation age ranging between 38 and 42 weeks; (b) onset of therapy within the first Month of life; (c) initial thyroxine (l-T(4)) dosage ranging from 10 to 12 microg/kg/day; (d) normalization of serum thyrotropin (TSH) levels before the age of 3 Months; (e) Monthly adjustments of l-T(4) dose during the first Year of life with serum TSH levels ranging from 0.5 to 4 mIU/l; (f) no major diseases and/or physical handicaps associated with CH; (g) availability of both thyroid scanning and knee X-rays at the time of treatment initiation; (h) availability of DQ assessment at an average age of 12 Months.


METHODS
BM was considered normal if the distal femur bony nucleus diameter exceeded 3 mm (group A) or retarded if either this nucleus was absent (subgroup B1) or its diameter was <3 mm (subgroup B2). DQ was evaluated with the Brunet-Lezine test.


RESULTS
In 44.3% of cases BM was either delayed (23.5%) or severely delayed (20.8%). The risk of BM retardation was higher in the patients with athyreosis than in the remaining patients (41/57 vs 44/135, chi(2)=25.13, P<0.005). BM-retarded infants showed a more severe biochemical picture of CH at birth and a lower DQ at the age of one Year compared with the group A patients. If compared with infants of subgroup B2 those of subgroup B1 exhibited significantly lower T(4) levels at birth and a more frequent association with athyreosis (70.0 vs 30.0%; chi(2)=7.49, P<0.01), whereas DQ was superimposable in both subgroups.


CONCLUSIONS
(a) BM at birth is delayed in almost half of CH patients and (b) CH severity per se can affect DQ at the age of 1 Year irrespective of other variables related to therapy.
Wasniewska
Malgorzata
M
Department of Pediatrics, University of Messina, Italy. wasniewska@yahoo.it
De Luca
Filippo
F
Cassio
Alessandra
A
Oggiaro
Nicola
N
Gianino
Paola
P
Delvecchio
Maurizio
M
Aiazzi
Rosalba
R
Stoppioni
Vera
V
Lombardo
Fortunato
F
Messina
Maria Francesca
MF
Valenzise
Mariella
M
Arrigo
Teresa
T
D001846:Bone Development; D015331:Cohort Studies; D003409:Congenital Hypothyroidism; D006801:Humans; D007037:Hypothyroidism / Q000175:diagnosis* / Q000188:drug therapy / Q000453:epidemiology; D007223:Infant; D007231:Infant, Newborn; D015997:Neonatal Screening; D011237:Predictive Value of Tests; D015995:Prevalence; D011379:Prognosis; D011596:Psychomotor Disorders / Q000175:diagnosis* / Q000453:epidemiology; D012189:Retrospective Studies; D012720:Severity of Illness Index; D013974:Thyroxine / Q000008:administration & dosage
D013974:Thyroxine