- 1. Surgical Endocrinology University of Virginia Clinical Clerkship in Surgery Peter I. Ellman M.D.
2. Plan for Talk
- Review the objectives as outlined by the Lawrence text.
- Discuss the anatomy, physiology, pathophysiology, diagnosis and treatment of thyroid, parathyroid and adrenal gland disorders.
- Discuss the MEN syndromes.
3. Objectives for the Thyroid Gland
- Discuss the evaluation and differential dx of a patient with a thyroid nodule.
- List the different types of thyroid cancer, their cell types of origin, and the appropriate theraputic strategy for each.
- Major risk factors for carcinoma of the thyroid gland and prognostic variables that dictate therapy.
- SX of Hyperthyroidism, DDX and TX
4. Objectives for the Parathyroid Glands
- Understand the role of the parathyroid glands in the physiology of calcium hemostasis.
- List the causes, symptoms, and signs of hypercalcemia.
- Know the difference between 1, 2,4 hyperparathyroidism.
- Discuss the evaluation and ddx of a paitent with hypercalcemia.
- Understand the management of acute and severe hypercalcemia.
- Surgical indications for hyperparathyroidism
- Complications of parathyroid surgery.
5. Objectives for the Adrenal Glands
- Describe the clinical features of Cushings syndrome and discuss how lesions in the pituitary, adrenal cortex and extraadrenal sites are distinguished diagnostically.
- Med and surg mgmt of patients with adrenal adenoma, pituitary adenoma causing adrenal hyperplasia, and with ACTH producing neoplasm.
- Path, clinical features, lab findings, W/U, mgmt. of pt with 1 aldosteronism.
- Discuss pheochromocytoma, signs and symptoms, W/U, mgmt.
- Discuss adrenal cortical carcinoma, assoicated signs and symptoms, W/U managment.
- Mgmt. and evaluation of incidentally discovered adrenal mass.
- Causes of adrenal insufficiency in surgical setting, as well as clinical and laboratory findings (RECENT JAMA ARTICLE)
6. Thyroid Anatomy
- Two lobes in neck, connected by isthmus at second tracheal ring.
- Embryologic origin at site of foramen cecum on tonguemigrates ventral to the hyoid bone why people get thyroglossal duct cyst.
- Arerial supply2 : Superior thyroid artery via the external carotid and Inferior thyroid artery via the Thyrocervical trunk (off the subclavian).
- Venous drainage3: through the superior, middle and inferior thryoid veins.
7. Thyroid Physiology
- Two groups of hormone producing cells
- 1: Follicular cells produce, store and release T 4and T 3
- 2: Parafollicular cells secrete calcitonin.
8. Follicular cells
- Capture iodide from the circulation and concentrate it and then oxidize it (organification, occuring in the apical membranes of the cells)
- Tyrosine residues of thyrogolbulin are then iodinated by oxidized iodides, forming monoiodotyrosine and diiodotyrosine which then couple to form T 4and T 3 -which is then stored.
- When thyroid stimulating hormone (TSH) stimulates the thyroid, the iodinated thyroglobulin then is taken into the cell and is hydrolized to T 4and T 3 -which is then released into the circulation.
- Besides stimulating the release of T3 and T4, TSH can stimulate the cell to increase production of thyroid hormones.
- TSH production is stimulated by Thyrotropin-releasing hormone (TRH) which is secretedby the hypothalamus. This intern is controlled by a feedback mechanism. Increased T3 and T4 have a negative feedback mechanism on TRH as well as TSH
10. The parafollicular (aka C cells)
- Secrete calcitonin which is stimulated by high serum calcium levels, which inhibits osteoclast activity, which in turn decreased calcium levels.
- Total absence of these cells produces no demonstrable negative physiologic effect!
11. Objective T1:W/U of Thyroid Nodule
- Always a thorough H & P (remember for oral exam).
- Hx of irradiation to the head or neck?
- Family history of MEN syndrome (will get to this later)
- Carefully palpate the thyroid and regional lymph nodes.
- How long has nodule been present? Any associated pain, hoarseness, dysphagia, dyspnea, or hemoptysis?
12. Objective T1:W/U of Thyroid Nodule
- Nodule shouldbe carefully examined to assess size, consitency, extension and fixation. Single or multiple?
- Is there cervical lymphadenopathy?
- Is there a rapid pulse, tremor, exopthalmos?
- Direct laryngoscopy is important in preoperative evaluation to assess for vocal cord paralysis.
13. DDX of thyroid nodule
- Follicular adenoma (most common adenoma)
- Colloid (macrofollicular)
- Metastatic Carcinoma to the Throid Gland.
- Fine needle aspiration is the single most important study in evaluating a thyroid mass.
- Only 3% of patients with a benign dx on FNA have thryoid cancer, and 85% of nodules identified as malignant on FNA are cancers at resection.
- 68% to 98% sensitive and 56% to 100% specific.
- Approx 75% areclassified as benign, 25% as suspicious and 5% as malignant.
- Follow patients with benign dx closely
- Follicular adenomas cannot be distinguished from follicular carcinoma by FNA and warrants a surgical exploration--most likely total thyroidectomy.
- do not do frozen section! It has been shown to be notoriously inaccurate!)
15. Other imaging modalities
- Not required for the routine evaluation of the vast majority of thyroid nodules.
- It is important to try and avoid the use of iondinated contrast materials preperatively.
- This can impair postoperative tx.
- A technicium thyroid scan may show a cold or hypofunctioning nodule. While it is c/w cancer, it could also be benign solid or cystic nodule that could be diagnosed with or even treated with FNA.
16. Use of ultrasound
- Good for determining the size, number and location of thyroid nodules accurately.
- Questionable use as a screening tool. Can increase the rate of finding incidentalomas.
17. Objective T2: List7Thyroid Carcinomas, Cell Types, and Tx.
- Metastatic Carcinoma to the Throid Gland.
18. Papillary CA
- Divided into the papillary, mixed papillary/follicular and follicular variant of papillary.
- Most Common Thyroid Malignancies!
- Arises fromFollicular Cells
- Histologically associated with fibrosis, calicifications, squamous metaplasia, psammoma bodies, lymphatic invasion.
19. Papillary CA TX
- Tx is somewhat controversial. At the very least pt needs ipsilateral lobectomy and isthmusectomy. Some surgeons recommend total thyroidectomy. It is important to know that you dont just take out the nodule!
- LND for clinically significant nodal disease.
- Surgery is followed by scanning with radioactive iodine to detect residual normal thyroid tissue as well as metastatic disease (lungs and bones).
20. Follicular CA- Overview
- Increased in regions of the world where iodine is deficient.
- Dx of malignancy requires that either vascular or capsular invasion by tumor be demonstrated.
- Again, FNA and Frozen Section cannot be trusted. Dx is deferred pending histologic review.
21. Follicular CACell origins
- Come from follicular cells (not surprising)
- On histologic exam there is a pauc