Thyroid, parathyroid, and adrenal diseases represent a complex spectrum of endocrine conditions that significantly impact our patients’ health and behavior. This chapter will review common thyroid issues, including goiter, hyperthyroidism/hypothyroidism, thyroid nodules, thyroiditis, and various thyroid cancers. Parathyroid-related disorders will also be discussed, including hyperparathyroidism and parathyroid cancer. Lastly, this chapter will review adrenal disorders, including Cushing’s syndrome, pheochromocytomas, and Multiple Endocrine Neoplasia (MEN) syndromes. Understanding the pathophysiology, diagnosis, and management of these endocrine disorders is crucial for effective treatment and patient care.