Final answer:
Thyroxine-binding globulin (TBG) deficiency in infants typically presents with low total circulating thyroid hormone levels but normal 'free' thyroid hormone levels and no signs of hypothyroidism. TBG deficiency does not usually cause thyroid dysfunction but may affect thyroid function test interpretations. It's distinct from iodine deficiency, which causes goiter and cognitive impairments.
Step-by-step explanation:
Thyroxine-Binding Globulin Deficiency Presentation in Infancy:
When considering thyroxine-binding globulin (TBG) deficiency in infancy, it is not directly linked to dietary iodine deficiency. However, it's part of a broader spectrum of conditions affecting thyroid function. Infants with TBG deficiency typically present with low levels of total circulating thyroid hormones but with normal levels of unbound or 'free' thyroid hormones and no clinical signs of hypothyroidism. Since TBG is a carrier protein that transports thyroid hormones in the blood, its deficiency does not usually disrupt thyroid hormone function but may alter the interpretation of thyroid function tests due to low total thyroid hormone levels.
Symptoms of iodine deficiency, a different condition, include goiter, cognitive impairments, and slowed growth, as thyroid hormones are essential for brain maturation. Treatment of TBG deficiency generally focuses on monitoring rather than direct intervention, while iodine deficiencies require dietary adjustments and may involve thyroid hormone replacement therapy.