Primary Hyperparathyroidism1

Question 1

How most patients are diagnosed with Primary Hyperparathyroidism?

Answer 1

Incidentally

Question 2

Which are common symptoms and signs of hyperparathyroidism?

Answer 2

Common symptoms and signs include bone pain or osteopenia/osteoporosis, kidney stones, constipation, urinary frequency and incontinence, pancreatitis, fatigue, muscle weakness, joint pain, difficulty concentrating, nausea, and vomiting.ﾠ

Question 3

What are the classic laboratory findings in patients with primary hyperparathyroidism (HPT)?

Answer 3

Elevated serum calcium and normal or elevated PTH. Usually in hypercalcemia PTH should be undetectable when hypercalcemia is due to causes other than HPT.

Question 4

What is the most common cause of primary hyperparathyroidism?

Answer 4

Single parathyroid adenoma (80%); other likely causes are double adenoma (5% to 10%), hyperplasia (5% to 10%), and parathyroid cancer (<1%).

Question 5

What is the only curative therapy for primary hyperparathyroidism?

Answer 5

SURGERY!!!

Question 6

What are the benefits from surgical management of primary parathyroidism?

Answer 6

Renal function and bone density improvement
Resolution of neuropsychiatric symptoms
Quality of life better
Prolongs survival (10% reduction if untreated)
Reduction in cardiovascular incidents
Low complication rates
Cost of parathyroidectomy at 5 years is less than the cost of surveillance

Question 7

What is the next step after making the biochemical diagnosis of hyperparathyroidism?

Answer 7

Parathyroid localization study

Question 8

What is the preferred parathyroid localization study?

Answer 8

Technetium-99m sestamibi scan with single photon emission computed tomography (SPECT)

Question 9

If the SPECT is negative, what is the next step?

Answer 9

Cervical ultrasound

Question 10

If the SPECT and cervical ultrasound are negative, what is the next step?

Answer 10

Bilateral internal jugular venous sampling in the operating room. A 22 gauge needle under ultrasound guidance is used to sample blood from both internal jugular veins prior to surgical incision, and the samples are sent for intraoperative PTH levels. If there is more than a 10% difference between the PTH levels, the test is considered positive, or lateralizing, and a parathyroidectomy is attempted on the side with the higher PTH level.

Question 11

How the gamma probe is used and can be useful during a parathyroidectomy?

Answer 11

Patient receives an injection of 10 mCi of sestamibi about 1 hour prior to surgery. In the OR, a background count is set by scanning the thyroid isthmus with the ?-probe. After incision, the ?-probe is utilized to scan for in vivo counts that are higher than the background counts. Once the abnormal parathyroid gland has been resected, the tissue is placed on the probe for an ex vivo count. If the ratio of ex vivo to ex vivo background counts is 20% or greater, the resected mass is hyperfunctioning parathyroid tissue. Radioguided techniques during parathyroidectomy are associated with a shorter operative time; they also facilitate intraoperative localization and dissection and are useful in reoperative cases.

Question 12

How intraoperative PTH testing works?

Answer 12

It is based upon the principle that PTH has a half-life of 2 to 4 minutes; therefore 5 minutes after resection of a single adenoma, the PTH level in the bloodstream should fall by 50%. However, if a second hyperfunctioning gland is present, the PTH levels should not fall by 50%, prompting the surgeon to explore for an additional abnormal parathyroid.ﾠ

Question 13

When a bilateral neck exploration is used for a parathyroidectomy?

Answer 13

1) the intraoperative PTH level did not fall after unilateral exploration
2) parathyroid localization studies are negative
3) suspected four-gland hyperplasia is suspected, such as when MEN 1 is present
4) the surgeon or patient prefers it.

Question 14

What are the surgical options if you find four-gland hyperplasia?

Answer 14

Subtotal parathyroidectomy (3.5 gland resection) or a total parathyroidectomy with forearm implantation is performed.

Question 15

If you can’t find the missing gland, what are the steps to follow?

Answer 15

1. Perform bilateral internal jugular venous sampling for PTH.
2. Look in the retroesophageal space.
3. Perform a cervical thymectomy.
4. Open the carotid sheath.
5. Search for an undescended gland, occasionally found in undescended thymic tissue.
6. Perform intraoperative ultrasound of the thyroid gland.
7. If the gland cannot be found, terminate the operation, leaving normal parathyroid gland intact.

Question 16

Which biochemical and introoperative findings should be suspicious of parathyroid cancer?

Answer 16

Patients who present with very high calcium (>14.0 mg/dL) and PTH (>300 pg/mL) levels. Intraoperatively, a cancerous parathyroid gland is rock hard and usually adherent to the thyroid gland.

Question 17

What is the definitive surgical treatment if parathyroid cancer is suspected?

Answer 17

Definitive treatment is an en bloc resection with an ipsilateral thyroid lobectomy and central lymph node dissection if enlarged nodes are present.

Question 18

What is the cause of having elevated PTH after appropiate parathyroid surgery for hyperparathyroidism?

Answer 18

Vitamin D deficiency and/or a reactionary secondary hyperparathyroidism

Question 19

When serum calcium and PTH should be measure post operatively and follow up?

Answer 19

Serum intact parathyroid hormone (iPTH; normal range, 10 to 65 pg/mL) and total serum calcium (normal range, 8.5 to 10.5 mg/dL) should be measured within 1 week of parathyroidectomy; if they fall within normal limits, they should be remeasured annually thereafter.