Treatment of disorders of the pituitary gland: Pearls and pitfalls from 30 years of experience

It has been my privilege to care for a large number of patients with disorders of the pituitary gland over the past 30 years. I would like to share with you a few thoughts on the pearls and pitfalls that I have found in my experience. I would emphasize that lesions involving the pituitary gland arise not only from within the gland, but also from the surrounding structures. A list of these lesions is long and includes a wide variety of tumors, with pituitary adenomas and craniopharyngiomas being the most common. Table 3.1 lists the tumor types that are found in the parasellar region and also the wide range of infectious and inflammatory lesions, a number of different cystic lesions as well as vascular lesions that can appear in this area. Although patients with pituitary lesions often present to endocrinologists or neurosurgeons, they more often are seen on the front lines by neurologists, ophthalmologists, otolaryngologists, and psychiatrists; in the emergency department; and, most importantly, by our colleagues in primary care and pediatrics. They are the ones who have to spot a patient with acromegaly or a patient with Cushing’s disease in their waiting room. Pituitary tumors are quite common. The most recent edition of the Central Brain Tumor Registry estimates that pituitary adenomas constitute 8.4% of brain and central nervous system tumors.1 They are the most common tumor in patients of ages 20 to 34 years and the second most common tumor in the 34to 44-year age group. They are 30% more common in the black population. We have found that forming a multidisciplinary pituitary clinic has been very helpful to our patients. Dr. Ariel Barkan, a pituitary endocrinologist, and I see all our patients together. We see them in the same room at the same time. We have other endocrinologists, neuroradiologists, neuro-oncologists, and neuro-ophthalmologists available for consultation when needed. I would now like to focus on some of the pitfalls that exist with these patients in hopes that you can learn from our experience. First, a few observations about the workup of thyroid function. As you know, it is common in primary care to screen patients with suspected clinical hypothyroidism with just serum thyroid-stimulating hormone (TSH). Physicians need to remember that a pituitary lesion will result in secondary hypothyroidism. This is identified by a low free thyroxine (T4), but a normal TSH. In primary hypothyroidism, the free T4 is low, but the TSH will be markedly elevated. A pitfall even when the free T4 is available is seen in the following situation. A 28-year-old woman presented with a symmetrically enhancing mass in the sella (Fig. 3.1A) and low thyroid function, as evidenced by a low free T4 of 0.56 ng/dL (normal, 0.7–1.8 ng/dL). What are the red flags in this picture? First, the mass is very symmetrical and uniformly enhancing, and, second, there is no TSH value. When we tested the TSH test, it was markedly increased to 126 mIU/L (normal, 7 mIU/L). This is consistent with primary hypothyroidism. The patient was treated with levothyroxine replacement, and the hypertrophy of the gland resolved (Fig. 3.1B). The pearls here are the following: