Complex sentence: It should be noted that while there are generic versions approved by the Food and Drug Administration, many endocrinologists and other prescribers specify a specific thyroid hormone brand because thyroid hormone has a narrow therapeutic index.
Split into simpler sentences: It should be noted that while there are generic versions approved by the Food and Drug Administration. Therefore, many endocrinologists and other prescribers specify a specific thyroid hormone brand because thyroid hormone has a narrow therapeutic index.