Introduction: Children with Down syndrome (DS) have a higher prevalence of hypothyroidism compared to the general population, and both conditions are linked to impaired growth. This study aimed to determine the prevalence and subtypes of hypothyroidism in DS and to compare growth outcomes with controls from general population at 2 years of age. Methodology: A retrospective review was conducted on 248 children with DS (aged 2–18 years) followed at Hospital Pakar Universiti Sains Malaysia from 2020 to 2025. Growth outcomes were analyzed in a subgroup of 41 DS children with hypothyroidism compared to 46 controls. Growth was compared using standard CDC charts for and z -scores calculated with PediTools (CDC 2–20 age). Mid-parental height, target height attainment, and height velocity were evaluated. Statistical analysis used t-tests and chi-square tests (p <0.05). Results: Of the 248 children with DS, 63.7% had hypothyroidism, predominantly subclinical (85.4%). No cases of acquired or secondary hypothyroidism were found. Children with DS had significantly lower mean height z-scores (−1.91 ± 1.45 vs. −0.54 ± 1.25; p <0.001), borderline lower height velocity (5.80 ± 2.15 vs. 6.92 ± 3.56 cm/year; p = 0.050), and fewer achieved target height (35% vs. 64.1%; p = 0.030) compared to controls. Baseline characteristics were similar between groups. Thyroid ultrasound showed normal anatomy in 50%, hypoplasia in 28.6%, and nodules in 21.4%. Common comorbidities included congenital heart disease (78.4%), pulmonary complications (16.2%), and other anomalies (32.4%). Conclusion Subclinical hypothyroidism was the predominant subtype in DS. Affected children demonstrated poorer growth, with reduced height z-scores, slower growth velocity, and lower likelihood of achieving target height.
Humans ; Down Syndrome ; Prevalence ; Hypothyroidism