A child has stunted growth, low IQ and mental retardation. It is most likely due to

A child has stunted growth, low IQ and mental retardation. It can be due to hyposecretion of thyroxine.

Stunted growth, low IQ, and mental retardation in a child can be attributed to a condition called congenital hypothyroidism. This condition occurs when there is an inadequate production of thyroid hormones, including thyroxine (T4), either due to a poorly functioning thyroid gland or a lack of proper development of the thyroid gland from birth.

Thyroid hormones are essential for proper growth and development, particularly for the development of the brain and nervous system. Inadequate levels of thyroid hormones during critical periods of growth can lead to cognitive and developmental delays, resulting in a range of symptoms such as stunted physical growth, reduced intelligence quotient (IQ), and mental retardation.