Comment from Gold Susan

Docket No. FDA-2015-D-4750-0439 Food and Drug Administration 5630 Fishers Lane, Room 1061 Rockville, MD 20852 Re: FDA’s Reclassification of Desiccated Thyroid Extract (DTE) as a Biologic I am writing to you as a patient who has depended on compounded natural desiccated thyroid (NDT) medication for more than twenty years, and for whom no other treatment has worked. Before I found compounded NDT, I tried every available alternative. Synthetic thyroid medications do not work for me. I also attempted commercial NDT products such as Armour Thyroid and NP Thyroid, but I react to multiple fillers, additives, and dyes present in all commercial formulations. Different patients have different and often multiple sensitivities, and no single commercial formula can ever address each patient's needs. Only individualized compounding can do that.( and critically, even if commercial NDT products such as Armour Thyroid were to remain available, they would still not be an option for me, as the fillers and dyes present in all commercial formulations remain an insurmountable barrier) A compounding pharmacy is not a preference for me. It is my only option. I read, a large-scale retrospective study of 1.26 million hypothyroid patients, published in the Journal of Clinical Endocrinology and Metabolism on June 20, 2025 (Beltrão et al., doi:10.1210/clinem/dgaf367), found that patients treated with therapies containing the synthetic liothyronine, including desiccated thyroid extract, had 27% lower dementia risk and 31% lower mortality risk compared to patients on synthetic levothyroxine alone, across 20 years of follow-up. These are clinically significant findings from one of the largest thyroid studies ever conducted, led by senior author Dr. Antonio Bianco at the University of Texas Medical Branch. Here is what thyroid hormone governs in the human body. The thyroid is the master regulator of human physiology. Thyroid hormone controls: Metabolism, growth, and body weight, Heart rate and cardiovascular function, Brain function, memory, and cognitive clarity, Mood and mental health, including depression and anxiety, Energy production at the cellular level, Muscle strength and function, Bone density and calcium balance, Digestive function and gut motility, Reproductive health and fertility, Cholesterol levels and lipid metabolism, skin, hair, and nail health, Immune system regulation, Sleep quality and circadian rhythm, Body temperature regulation, Fetal brain development during pregnancy. When thyroid hormone is not properly replaced, every one of these systems is compromised. For patients who do not do well on synthetic medications or commercial preparations, removing access to compounded NDT does not push us toward a different treatment. It removes the treatment entirely. The FDA's classification of NDT as a biologic is legally and scientifically inconsistent with the agency's own prior guidance, which has acknowledged that a product containing a protein only as an inactive ingredient is not considered a biologic. Thyroglobulin is an inactive component of NDT; the active therapeutic agents are T3 and T4. NDT has been safely compounded for over 120 years, predating the FDA itself, and is defined as a drug under the USP Thyroid monograph. It is not a new biologic therapy. I respectfully request: Direct the FDA to reclassify NDT as a drug rather than a biologic, immediately restoring the legal pathway for pharmacy compounding. Establish legal protection ensuring that compounding pharmacies retain the right to prepare individualized NDT for patients who cannot tolerate commercial formulations. Protect the continued availability of pharmaceutical-grade porcine thyroid powder from qualified manufacturers as an essential medical ingredient, the right to compound NDT and the ingredient supply chain are inseparable. Please do not take this medication away from us. We are asking only to preserve access to a safe, natural, physician-prescribed medication with a proven 120-year record. Respectfully,