Parathyroid Flashcards
The parathyroids receive their blood supply from where?
all four get their arterial inflow from the inferior thyroid artery
What is the embryologic origin of the parathyroids?
- superior from the fourth pharyngeal pouch
- inferior from the third
How are the parathyroids located relative to the RLN?
- superior are posterior and lateral to the nerve
- inferior and anterior and medial
What cells release parathyroid hormone? Calcitonin?
- PTH from chief cells
- calcitonin from c-cells of the thyroid
What are the effects of PTH?
- stimulates osteoclasts
- stimulates calcium resorption and phosphate secretion in the kidneys
- stimulates activation of vit D in the kidneys
How does vitamin D increase calcium?
by stimulating increased absorption of Ca and P from the GI tract
What are the most common causes of hypercalcemia in an inpatient and outpatient setting?
- inpatient: malignancy
- outpatient: primary hyperparathyroidism
Which lung cancer releases PTHrP?
squamous cell
How is hypercalcemic crisis treated?
- high volume of normal saline
- lasix
- bisphosphates
What is the most specific test for diagnosing hyperparathyroidism?
chloride/phosphate > 33
What are the indications of symptomatic patients with hyperparathyroidism to undergo parathyroidectomy?
- calcium > 1 above normal
- CrCl < 60
- poor access to care/follow up
- age < 50
What confirms adequate resection of a parathyroid adenoma?
more than 50% drop on intra-op rapid PTH assay
In which patients do you see tertiary hyperparathyroidism and how is this treated?
- usually in post-renal transplant patients
- due to long-term dysregulation of the feedback loop, triggering autonomous PTH production by parathyroids
- treated with subtotal parathyroidectomy
How is secondary hyperparathyroidism treated?
- calcium and vit D supplements
- phosphate binders
- renal diet
How is parathyroid carcinoma treated?
en bloc resection with ipsilateral thyroid and central neck dissection
