1. Cortisol synthesis requires 21-hydroxylase. When 21-hydroxylase is lacking (congenital adrenal hyperplasia, CAH), what happens to the levels of cortisol and their regulating hormones? Explain why. How does this hormonal change affect the body? 2. Iodine deficiency can cause thyroid enlargement and goiter. What is the underlying mechanism? Consider the case of lacking 21-hydroxylase..