Parathyroid Flashcards
Are chemo and radiation beneficial for parathyroid carcinoma?
No
What do you do if you encounter a parathyroid carcinoma when doing a parathyroidectomy?
En bloc resection of the parathyroid gland and ipsilateral thyroid lobe along with regional lymph nodes.
Indications for parathyroidectomy?
1) Age < 50 y.o.
2) Ca > 1 mg/dl over normal
3) Urinary Ca > 400 mg/24 hours
4) Osteoporosis T score < -2.5
5) Compression fractures, nephrolithiasis
6) CrCl < 60
7) Poor followup
Indication for bilateral exploration for primary hyperparathyroidism?
Lithium exposure -> HPT; b/c there is an increased incidence in 4 gland hyperplasia compared to gen pop
Anatomy of superior parathyroid
Post/Lat to recurrent laryngeal nerve
From 4th pharyngeal pouch
Anatomy of inferior parathyroid
Ant/Med to recurrent laryngeal nerve
From 3rd pharyngeal pouch (just like the thymus)
More variable location
Blood supply to parathyroid glands
Inferior parathyroid artery (80%) - from thyrocervical trunk
Parathyroid function
Cheif cells - PTH in response to low Ca
Parafollicular C cells - Release calcitonin in response to high Ca (actually located in thyroid)
Vit D process
Ingested then hydroxylated @ 25 in the liver; hydroxylated @ 1 in the kidney -> now most active
Parathyroid hormone acts on?
2 sites:
Bone: Stimulates osteoclasts for resorption of Ca/P
Kidney: Stimulates resorption of Ca, inhibits resorption of P/HCO3
People with high PTH have very low P
Vit D affects
Stimulates absorption of Ca/P in gut
Stimulates absorption of Ca; and wasting of P in kidneys
Calcitonin affects
Bones: Inhibits osteoclasts
Kidney: Inhibits resorption of Ca/P
HyperCa presentation
1) on labs as high Ca
MC cause in outpatient setting- > primary hyperPTH
2) MC inpatient cause -> Cancer
Ex: Squamous cell cancer (pthrp), breast cancer
HyperCa crisis tx
1) Fluids - NS @ 300 cc/hr
2) When euvolemic add lasix
Primary hyperPTH
MC cause single adenoma
Other cause, hyperplasia of all glands, cancer, MEN 1, 2A
