Diseases Of The Parathyroid Glands (both pathology and Crutchfield lectures) Flashcards
What are the two cells found in parathyroid glands
1) chief principle cells
- stains basophilic
- actually secrete PTH
- **exhibits negative feedback by increased free calcium in blood
2) oxyphil cells
- stain acidophilc and contains large amounts of mitochondria
Hyperparathyroidism
Primary
- autonomous overproduction of PTH
- most common cause of hypercalcemia
- is caused by: adenoma (90%), primary hyperplasia (9%) and parathyroid carcinoma (1%)
- 75-85% of tumors ar solitary
Secondary
What are the two gene abnormaltes associated with parathyroid tumors
Cyclin D1 gene rearrangements
- usually a inversion on chromosome 11 which moves cyclin D1 next to PTH (cyclin D1 is a positive regulator so it will excessively promote PTH gene transcription)
- 10-20% adenomas have this
MEN1 mutations
- 10-30% of Adenomas have this
Difference between parathyroid hyperplasia and parathyroid adenomas
Adenomas = solitary nodules
- usually small tan lesions that are well defined and weigh less than 5g
Parathyroid hyperplasia = diffuse or multi nodular pattern usually
- usually grey-white neoplasms that weigh near 10g
both show primary Chief cells on histology and near no oxyphil cells
What can bones seen in chronic hyperparathyroidism sometimes look like on gross examination
“Brown tumors of bone”
- caused by aggregations or osteoclasts, reactive giant cells and hemorrhagic debris
Clincial features of primary hyperparathyroidism
More common women (4:1) and more common in adults
Most common manifestation is increased serum calcium and if it becomes symptomatic most common is polyuria with kidney stones
What is the msot common cause of symptomatic pseudo hyperparathyroidism?
Hypercalcemia of malignancy
- results in apparent hyperparathyroidism but there will be Low PTH since PTHrP is mimicking it
Differences in lab values between hyperparathyroidism caused by parathyroid hyperfunction and caused by nonparathyroid diseases
Caused by parathyroid hyper-function
- excess PTH
- hypophosphatemia
- high levels of both calcium and phosphate in ruin
Caused by non-parathyroid diseases
- low PTH
- hyperphosphatemia
- high levels of calcium in urine but low phosphate
What symptoms are common in primary hyperparathyroidism
Painful bones
Renal stones
Abdominal pains
Polyuria/polydipsia
Corneal calcification
Lethargy
What is the most common cause of secondary hyperparathyroidism
Chronic renal failure
Also almost always shows hyperplasia in parathyroid glands
What is a commonly feared consequence of hyperphosphatemia
Calciphylaxis
- causes metastatic calcification of blood vessels which leads to serious ischemic damage
What are the most common causes of hypoparathryodism?
Surgical ablation
Congenital absence in Thymic aplasia
- seen is Di-George syndrome (22q11)
Autoimmune hypoparathryodism
Hypoparathryodism clinical manifestations
Are secondary to hypocalcemia
- neuropathic damage (tingling, muscle spasms, fascial spasms and tetanus)
- cardiac arrhythmias
- increased intracranial pressure and seizures
Chronic = cataracts and dental abnormalties
What is the most common tumor of hyperparathyroidism?
Solitary benign adenoma in a parathyroid gland
Who first discovered parathyroid glands?
Ivan sandstrom
Who is rosalyn halos?
Won the Nobel prize for coming up with the radioimmunoassay for insulin and PTH
What is the blood supply to the parathyroid glands?
Inferior thyroid artery
- a branch of the thryocervical trunk
What are patient symptoms and lab values that are suggestive of parathyroid disorders
Features
- ab pain
- coughing/dyspnea
- headache
- seizures
- bone pain
- calcium stones
- pancreatitis
- anger/depression that is unexplained (psychic overtones)
- palpitation and arrhythmias
- masses, nausea/vomiting
Lab values
- high serum calcium
- high PTH
- low phosphate in blood
Hypocalcemia = Chevstek (tap facial nerve and cause tetany), trousseau sign (carpal pedal spasm When you blow up a leg cuff 20 mg over their arterial pressure for 2-3 seconds)
What are the most common sites for normal parathyroid glands
60% = paraesophageal
- usually in the esophageal groove and posterior to the thyroid gland
25% = thymus
10% = intrathryoidal
4% = carotid sheath
1% = everywhere else
How do you calculate the correct patient calcium level from a BMP
Using the following formula:
(Normal albumin (4.0) - current albumin measured times 0.8)
- take this value and add it to the measured calcium level in the BMP
this gives you a corrected calcemia level based on hypo or hyper albuminemia levels
What is the importance of the carotid body and artery in thyroid gland/parathyroid gland operations
If you bump or misplace the carotid body/sinus = bradycardia and hypotension
- can give lidocaine to prevent this**
- this derived from neural crest cells and is VERY sensitive
sometimes parathyroid gland tumors can get inside the carotid sheath
Review of what are the common causes of Virchow node?
Women = breast or lung
Men = lung
both also are possible to be GI malignancy
What is the best scans to use to look at parathyroid glands?
DONT use MRI/CT or Xrays (none of these really can view the parathyroid glands properly)
- it still can be but is so unusual that it is not first line for diagnosing
Instead use a physical exam, lab levels and EV scanning
- Use a sestamibi scan uses radioactive technetium-99 (same cardiac nuclear medicine scan so will also light up the heart). This is good for primary parathyroid hyperplasia or adenomas .
- sestamibii scans often can be misread**
Use of 11 C-choline and 18 Flurorocholine complexes in PET/CT scans for parathyroid
This is another way to find parathyroid adenomas using CT cross section
What MEN syndrome is most heavily tied to parathyroid hyperplasia
MEN1
- also very common shows zollinger Ellison syndrome with gastrinomas
