Thyroid hormone is critical for normal neurocognitive development in young infants, and even transient hypothyroidism can cause adverse neurodevelopmental outcomes. In a population of infants with CHD who already bear a high risk of long-term developmental delay, detection of hypothyroidism, even of a transient nature, may be even more consequential, and routine periodic monitoring of thyroid function may be necessary to reduce the risk of neurodevelopmental disabilities

Inclusion Criteria:

• All children since birth up to age of 12 years old including both genders diagnosed to have CHD exposed to radiation, contrast or not.

Exclusion Criteria:

• above 12 years old

• Place of the study: Sohag University Hospital (pediatrics department -cardiology unit).
• Sample size the whole sample size will be at least 100 child diagnosed as CHD divided equally into two groups (group A and B) Group A: children exposed to any type of radiation or contrast Group B : children not exposed to an type of radiation or contrast