Spring break starts tomorrow! Woo! Studying will still be going on, but now I get to shift to reviewing old material. Yay? But before they set us loose, we had to get a start on our new block of material, endocrinology, the study of hormones and glands. See you in a week!
TuesdayIL: When looking at pituitary tumors, they become clinically noticeable from either mass effect or excess hormonal production, but rarely both. This makes sense, since if a tumor secretes a hormone, it will cause more and more problems as it grows and will be noticed due to it's systemic effects before it gets noticed for pushing on the neighboring brain regions.
Neuroblastoma and Wilm's tumors look very similar but Wilm's rarely metastasizes to bone, so if you see bone mets, think neuroblastoma.
WednesdayIL: Near the end of a pregnancy, the pituitary gland is hypertrophied and at the limit of its vascular supply (it's bigger and is barely getting enough blood). Though this growth is useful to produce the hormones needed to maintain the gravid state, it puts the pituitary at risk of infarction (stroke). If there is substantial blood loss during delivery, this can exacerbate the problem. If an infarction happens at this point, it's called Sheehan syndrome. Loss of pituitary function can be pretty subtle and, if it's a small infarct, could go unnoticed for years. The main symptoms are lethargy, anorexia, weight loss and an inability to lactate. Since the pituitary controls the thyroid gland, you can also have hypothyroidism, showing water retention, more fatigue, cold intolerance, among many other symptoms.
TIL: TSH level manipulation with thyroid cancer is complicated. Normally, you want to suppress thyroid stimulating hormone (TSH) in thyroid cancer treatment for the fairly obvious reason that part of the thyroid is already growing out of control (hence the cancer), so stimulating it would be counterproductive. Simple, right? Here's the problem: one of the treatments for thyroid cancer is using I-131, a radioactive isotope of iodine, to kill off cancerous thyroid cells. This is a great targeted form of chemotherapy since the thyroid is the only part of the body that takes up iodine in any significant amount. But in order for the thyroid to do this function, it needs to be stimulated by TSH. So, if this treatment is used you must closely regulate the TSH level so that it's high when you want iodine to be absorbed, but low the rest of the time to deter unwanted growth.
With hyperthyroidism caused by subacute thyroiditis, the thyroid does not actually produce any not hormone than usual. Instead, the inflamed state allows more of the preformed stored hormone to leak out of the thyroid follicles than normal.
My favorite disease of the week is the so-called hamburger thyrotoxicosis, which is community-wide outbreaks of hyperthyroidism caused by the accidental addition of bovine thyroid gland into hamburger meat. Thyroid hormones are very potent and if thyroid tissue gets mixed into a large batch of ground beef, it can cause symptoms in hundreds of people. The practice of using the meat near the neck of the cow is strictly prohibited, so this rarely happens and is more commonly seen when a family farm butchers a cow for their own use and doesn't follow the industry guidelines.
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