If hypothyroidism is not treated, a cluster of symptoms called myxedema may appear. These symptoms include an expressionless face, thin hair, puffiness around the eyes, enlarged tongue, and thick skin that feels cool and doughy.
In babies born with hypothyroidism, there may be a hoarse cry, slow growth, unusual sleepiness, constipation and feeding problems. If hypothyroidism is not treated, the child may be unusually short and have dry skin, thin hair, an unusual facial appearance, a protruding abdomen, delayed eruption of teeth and problems with mental development. When hypothyroidism occurs in an older child, it may delay puberty and cause other symptoms similar to those seen in adults.