Parathyroid

Question 1

how many parathyroids are there?

Answer 1

usually four

Question 2

what is the usual position of the inferior parathyroid glands?

Answer 2

posterior and lateral behind the thyroid and below the inferior thyroid artery

Question 3

what is the most common site of an ‘extra’ gland?

Answer 3

thymus

Question 4

if only three parathyroid glands are found at surgery, where can the fourth be hiding?

Answer 4

thyroid gland
thymus/mediastinum
carotid sheath
tracheoesophageal groove
behind the esophagus

Question 5

what is the embryologic origin of the superior parathyroid glands?

Answer 5

fourth pharyngeal pouch

Question 6

what is the embryologic origin of the inferior parathyroid glands?

Answer 6

third pharyngeal pouch

Question 7

what supplies blood to all four parathyroid glands?

Answer 7

inferior thyroid artery

Question 8

what is the most common cause of hypercalcemia in outpatients?

Answer 8

hyperparathyroidism

Question 9

what cell type produces PTH?

Answer 9

chief cells produce PTH

Question 10

what are the major actions of PTH?

Answer 10

increases blood calcium levels
- takes from bone breakdown, GI absorption, increased resorption from kidney, excretion of phosphate by kidney
decreases serum phosphage

Question 11

how does vitamin D work?

Answer 11

increases intestinal absorption of calcium and phosphate

Question 12

where is calcium absorbed?

Answer 12

duodenum and proximal jejunum

Question 13

define primary hyperparathyroidism?

Answer 13

increased secretion of PTH by parathyroid glands

- marked by elevated calcium, low phosphorus

Question 14

define secondary hyperparathyroidism?

Answer 14

increases serum PTH resulting from calcium wasting caused by renal failure or decreased GI calcium absorption, rickets or osteomalacia
- calcium levels are usually low

Question 15

define tertiary hyperparathyroidism?

Answer 15

persistant hyperparathyroidism after correction of secondary hyperparathyroidism
- results from autonomous PTH secretion not responsive to the normal negative feedback due to elevated Ca2+ levels

Question 16

what are the methods of imaging the parathyroids?

Answer 16

surgical operation
ultrasound
sestamibi scan
CT scan

Question 17

what are the indications for a localizing preoperative study?

Answer 17

reoperation for recurrent hyperparathyroidism

Question 18

what its the most common cause of primary hyperparathyroidism?

Answer 18

adenoma

Question 19

what are the risk factors for primary hyperparathyroidism?

Answer 19

family history
MEN-I and MEN-IIa
irradiation

Question 20

what are the signs/symptoms of primary hyperparathyroidism?

Answer 20

“stones, bones, groans, and psychiatric overtones”

• stones: kidney stones
• bones: bone pain, pathologic fractures, subperiosteal resoprtion
• groans: muscle pain and weakness, pancreatitis, gout, constipation
• psychiatric overtones: depression, anorexia, anxiety
• other: polydipsia, weight loss, HTN, polyuria, lethargy

Question 21

what is the 33-to-1 rule?

Answer 21

most patients with primary hyperparathyroidism have a ratio of serum Cl- to phosphate >= 33

Question 22

what plain X-ray findings are classic for hyperparathyroidism?

Answer 22

subperiosteal bone resorption

• usually in hand digits
• said to be pathognomonic for hyperparathyroidism

Question 23

how is primary hyperparathyroidism diagnosed?

Answer 23

labs

• elevated PTH, hypercalcemia, decreased phosphorus, increased chloride
• urine calcium should be checked for familial hypocalciruic hypercalcemia

Question 24

what is familial hypocalciuric hypercalcemia?

Answer 24

familial (autosomal dominant) inheritance of a condition of asymptomatic hypercalcemia and low urine calcium, with or without elevated PTH

• in contrast, hypercalcemia from hyperparathyroidism results in high levels of urine calcium
• surgery to remove parathyroid glands is not indicated for this diagnosis

Question 25

what is the differential diagnosis of hypercalcemia?

Answer 25

CHIMPANZEES - Calcium overdose - Hyperparathyroidism, Hyperthyroidism, Hypocalciuric Hyprecalcemia - Immobility/Iatrogenic (thiazide diuretic) - Metastasis/Milk alkali syndrome (rare) - Paget's disease (bone) - Addison's disease/acromegaly - Neoplasm (colon, lung, breast, prostate, multiple myeloma) - Zollinger-Ellison syndrome - Excessive Vitamin D - Excessive Vitamin A - Sarcoid

Question 26

what is the initial medical treatment of hypercalcemia (primary hyperparathyroidism)?

Answer 26

medical - IV fluids, furosemide - NOT thiazide diuretics

Question 27

although most recommend surgery for asymptomatic primary hyperparathyroidism, when is it considered mandatory?

Answer 27

ROACH - Renal insufficiency - Osteoporosis - Age <50 - Calcium >1mg/dL above upper limit of normal - Hypercalciuria >400mg/d Ca2+ excretion

Question 28

what is the definition treatment of primary hyperparathyroidism from HYPERPLASIA?

Answer 28

neck exploration removing all parathyroid glands and leaving at least 30mg of parathyroid tissue placed in the forearm muscles

Question 29

what is the definitive treatment of primary hyperparathyroidism from parathyroid ADENOMA?

Answer 29

surgically remove adenoma (send for frozen section) and biopsy all abnormally enlarged parathyroid glands (some experts biopsy all glands)

Question 30

what is the definitive treatment of primary hyperparathyroidism from parathyroid CARCINOMA?

Answer 30

remove carcinoma, ipsilateral thyroid lobe, and all enlarged lymph nodes (modified radical neck dissection for LN metastases)

Question 31

what is the definitive treatment of secondary hyperparathyroidism?

Answer 31

correct calcium and phosphate | perform renal transplantation

Question 32

what is the definitive treatment of tertiary hyperparathyroidism?

Answer 32

correct calcium and phosphage perform surgical operation to remove all parathyroid glands and reimplant 30-40mg in the forearm if refractory to medical management

Question 33

why place 30-40mg of sliced parathyroid gland into the forearm?

Answer 33

to retain parathyroid function | - if hyperparathyroidism recurs, remove some of the parathyroid gland from the easily accessible forearm

Question 34

what must be ruled out in the patient with hyperparathyroidism from hyperplasia?

Answer 34

MEN-I and MEN-IIa

Question 35

what carcinomas are commonly associated with hypercalcemia?

Answer 35

breast cancer metastases | prostate cancer, kidney cancer, lung cancer, pancreatic cancer, multiple myeloma

Question 36

what is the most likely diagnosis if a patient has a palpable neck mass, hypercalcemia, and elevated PTH?

Answer 36

parathyroid carcinoma | - vast majority of other causes of primary hyperparathyroidism have non palpable parathyroids

Question 37

what is parathyroid carcinoma?

Answer 37

primary carcinoma of the parathyroid gland

Question 38

what is the number of glands usually affected in parathyroid carcinoma?

Answer 38

1

Question 39

what are the signs/symptoms of parathyroid carcinoma?

Answer 39

hypercalcemia, elevated PTH, PALPABLE parathyroid gland, pain in neck, recurrent laryngeal nerve paralysis, hypercalcemic crisis

Question 40

what is the common tumor marker for parathyroid carcinoma?

Answer 40

human chorionic gonadotropin (HCG)

Question 41

what are the possible postoperative complications after a parathyroidectomy?

Answer 41

``` recurrent nerve injury - unilateral: voice change - bilateral: airway obstruction neck hematoma - open at bedside if breathing is compromised hypocalcemia superior laryngeal nerve injury ```

Question 42

what is 'hungry bone syndrome'?

Answer 42

severe hypocalcemia seen after surgical correction of hyperparathyroidism as chronically calcium-deprived bone aggressively absorbs calcium

Question 43

what are the signs/symptoms of postoperative hypocalcemia

Answer 43

perioral tingling, paresthesia, +Chvostek's sign, +Trousseau's sign, +tetany

Question 44

what is the treatment of hypoparathyroidism?

Answer 44

actue: IV calcium chronic: PO calcium, and vitamin D

Question 45

What is parathyromatosis?

Answer 45

multiple small hyper functioning parathyroid tissue masses found over the neck and mediastinum - thought to be formed from congenital rests or spillage during surgery - remove surgically