Signs and Symptoms of Hypothyroidism in Infants: What Parents Should Know

Hypothyroidism, or underactive thyroid, in infants is a condition that occurs when the thyroid gland fails to produce sufficient hormones necessary for normal growth and development. When left undiagnosed or untreated, it can lead to serious developmental delays and long-term health complications. Recognizing the early signs is crucial for timely intervention and effective management.

Distinctive Physical Characteristics

One of the most noticeable indicators of congenital hypothyroidism in newborns is an unusual facial appearance. Infants may present with a larger-than-average head size and a shorter neck, contributing to a unique physical profile. Facial features often include swollen eyelids, a flattened nasal bridge, and a broad, protruding tongue. These characteristics, combined with sparse hair and dry skin, can help healthcare providers identify potential thyroid issues during routine newborn screenings.

In addition to these visible traits, affected babies may appear expressionless or lethargic. Their responsiveness to stimuli tends to be delayed, and they may show little interest in their surroundings—a sign of reduced neurological activity linked to low thyroid hormone levels.

Neurological and Cognitive Development Delays

Thyroid hormones play a vital role in brain development during infancy. A deficiency can significantly impair cognitive function, leading to difficulties with memory retention, poor concentration, and slower information processing. Studies show that untreated hypothyroid infants are at higher risk of having lower IQ scores compared to their peers.

Early detection through newborn screening programs allows for prompt treatment with synthetic thyroid hormone (levothyroxine), which can greatly improve neurodevelopmental outcomes. Delayed diagnosis, however, may result in permanent intellectual disabilities or learning challenges later in life.

Growth and Skeletal Development Concerns

Another critical area affected by infant hypothyroidism is physical growth. Children with this condition typically experience stunted growth and fall below standard height percentiles for their age. Bone maturation is also delayed—often by two years or more—when assessed through bone age X-rays.

Without adequate thyroid support, the body's ability to build and maintain healthy bones is compromised. This delay not only affects stature but can also impact motor skill development, such as sitting, crawling, and walking, which may occur much later than expected.

Importance of Early Screening and Treatment

Most developed countries now include congenital hypothyroidism in their standard newborn screening panels. Blood tests conducted within the first few days of life can detect abnormal thyroid-stimulating hormone (TSH) levels, enabling immediate follow-up and treatment.

With proper medical care, including daily hormone replacement therapy and regular monitoring by a pediatric endocrinologist, infants with hypothyroidism can achieve normal growth and cognitive development. Parents should remain vigilant for subtle signs and ensure all recommended screenings are completed on schedule.