Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
54 Cards in this Set
- Front
- Back
|
How many parathyroids are there? |
Usually 4 (two superior and two inferior) |
|
|
What percentage of patients have five parathyroid glands? |
~5% |
|
|
What percentage of patients have three parathyroid glands? |
~10% |
|
|
What is the usual position of the inferior parathyroid glands? |
Posterior and lateral behind the thyroid and below the inferior thyroid artery |
|
|
What is the most common site of an "extra" parathyroid gland? |
Thymus gland |
|
|
What percentage of patients have a parathyroid gland in the mediastinum? |
~1% |
|
|
If only three parathyroid glands are found at surgery, where can the fourth one be hiding? |
- Thyroid gland - Thymus / mediastinum - Carotid sheath - Tracheoesophageal groove - Behind the esophagus |
|
|
What is the embryologic origin of the superior parathyroid glands? |
Fourth pharyngeal pouch |
|
|
What is the embryologic origin of the inferior parathyroid glands? |
Third pharyngeal pouch (counter-intuitive) |
|
|
What supplies blood to the parathyroid glands? |
Inferior thyroid artery |
|
|
What percentage of patients have all four parathyroid glands supplied by the inferior thyroid arteries exclusively? |
~80% |
|
|
What id DiGeorge's syndrome? |
Congenital absence of the parathyroid glands and the thymus |
|
|
What is the most common cause of hypercalcemia in hospitalized patients? |
Cancer |
|
|
What is the most common cause of hypercalcemia in out-patients? |
Hyper-parathyroidism |
|
|
What cell type produces PTH? |
Chief cells |
|
|
What are the major actions of PTH? |
- Increases blood calcium levels (takes from bone breakdown, GI absorption, increased reabsorption from kidney, excretion of phosphate by kidney) - Decreases serum phosphate |
|
|
How does vitamin D work? |
Increases intestinal absorption of calcium and phosphate |
|
|
Where is calcium absorbed? |
Duodenum and proximal jejunum |
|
|
Define primary hyperparathyroidism? |
Increased secretion of PTH by parathyroid gland(s); marked by elevated calcium, low phosphorus |
|
|
Define secondary hyperparathyroidism? |
- Increased serum PTH resulting from calcium wasting caused by renal failure or decreased GI calcium absorption, rickets or osteomalacia - Calcium levels are usually LOW |
|
|
Define tertiary hyperparathyroidism? |
- Persistent HPTH after correction of secondary HPTH - Results from autonomous PTH secretion not responsive to normal negative feedback due to elevated calcium levels |
|
|
What are the methods of imaging the parathyroids? |
- Surgical operation - U/S - Sestamibi scan - 201-TI (technetium)-thallium subtraction scan - CT / MRI - A-gram (rare) - Venous sampling for PTH (rare) |
|
|
What are the indications for a localizing pre-op study of parathyroids? |
Re-operation for recurrent hyperparathyroidism |
|
|
What is the most common cause of primary HPTH? |
Adenoma (>85%) |
|
|
What are the etiologies of primary HPTH and percentages? |
- Adenoma (~85%) - Hyperplasia (~10%) - Carcinoma (~1%) |
|
|
What is the incidence of primary HPTH in the US? |
~1/1000-4000 |
|
|
What are the risk factors for primary HPTH? |
- Family history - MEN-I and MEN-IIa - Irradiation |
|
|
What are the signs/symptoms of primary HPTH hypercalcemia? |
Stones, bones, groans, and psychiatric overtones: - Stones: kidney - Bones: pain, pathologic fractures, subperiosteal resorption - Groans: muscle pain and weakness, pancreatitis, gout, constipation - Psychiatric overtones: depression, anorexia, anxiety - Other: polydipsia, weight loss, HTN (10%), polyuria, lethargy |
|
|
What is the "33 to 1" rule? |
Most patients with primary HPTH have a ratio of serum (Cl-) to phosphate >33:1 |
|
|
What plain x-ray findings are classic for primary HPTH? |
Subperiosteal bone resorption (usually in hand digits; said to be "pathognomonic for HPTH!") |
|
|
How do you diagnose primary HPTH? |
Labs: - Elevated PTH (hypercalcemia, decreased phosphorus, increased chloride) - Urine calcium should be checked for familial hypocalciuric hypercalcemia |
|
|
What is familial hypocalciuric hypercalcemia? |
Familial (autosomal dominant) inheritance of a condition of asymptomatic hypercalcemia and low urine calcium, with or without elevated PTH
In contrast, hypercalcemia from HPTH results in high levels of urine calcium
Note: surgery to remove parathyroid glands is not indicated for this diagnosis |
|
|
How many of the glands are usually affected by parathyroid hyperplasia? |
4 |
|
|
How many of the glands are usually affected by parathyroid adenoma? |
1 |
|
|
How many of the glands are usually affected by parathyroid carcinoma? |
1 |
|
|
What percentage of parathyroid adenomas are not single but found in more than one gland? |
~5% |
|
|
What is the differential diagnosis of hypercalcemia? |
CHIMPANZEES: - Calcium overdose - Hyperparathyroidism (primary/secondary/tertiary) - Hyperthyroidism, Hypocalciuric Hypercalcemia (familial) - Immobility / Iatrogenic (thiazide diuretics) - Metastasis / Milk alkali syndrome (rare) - Paget's disease (bone) - Addison's disease / acromegaly - Neoplasm (colon, lung, breast, prostate, multiple myeloma) - Zollinger-Ellison syndrome - Excess vitamin D - Excess vitamin A - Sarcoid |
|
|
What is the initial medical treatment of hypercalcemia (primary HPTH)? |
Medical: - IV fluids - Furosemide (not thiazide diuretics) |
|
|
What is the definitive treatment of primary HPTH resulting from hyperplasia? |
Neck exploration removing all parathyroid gland and leaving at least 30 mg of parathyroid tissue placed in the forearm muscles (non-dominant arm) |
|
|
What is the definitive treatment of primary HPTH resulting from adenoma? |
Surgically remove adenoma (send for frozen section) and biopsy all abnormally enlarged parathyroid glands (some experts biopsy all glands) |
|
|
What is the definitive treatment of primary HPTH resulting from carcinoma? |
Remove carcinoma, ipsilateral thyroid lobe, and all enlarged lymph nodes (modified radical neck dissection for LN metastases) |
|
|
What is the definitive treatment of secondary HPTH? |
Correct calcium and phosphate; perform renal transplant (no role for parathyroid surgery) |
|
|
What is the definitive treatment of tertiary HPTH? |
- Correct calcium and phosphate - Perform surgical operation to remove all parathyroid glands and reimplant 30-40 mg in the forearm if REFRACTORY to medical management |
|
|
Why place 30-40 mg of sliced parathyroid gland in the forearm to treat tertiary HPTH? |
To retain parathyroid function; if HPTH recurs, remove some of the parathyroid gland from the easily accessible forearm |
|
|
What must be ruled out in the patient with HPTH from hyperplasia? |
MEN type I and MEN type IIa |
|
|
What carcinomas are commonly associated with hypercalcemia? |
- Breast cancer metastases - Prostate cancer - Kidney cancer - Lung cancer - Pancreatic cancer - Multiple myeloma |
|
|
What is the most likely diagnosis if a patient has a PALPABLE neck mass, hypercalcemia, and elevated PTH? |
Parathyroid carcinoma (vast majority of other causes of primary HPTH have non-palpable parathyroids) |
|
|
What is parathyroid carcinoma? |
Primary carcinoma of the parathyroid gland |
|
|
What is the number of glands usually affected by parathyroid carcinoma? |
1 |
|
|
What are the signs/symptoms of parathyroid carcinoma? |
- Hypercalcemia - Elevated PTH - Palpable parathyroid gland (50%) - Pain in neck - Recurrent laryngeal nerve paralysis (change in voice) - Hypercalcemic crisis (usually associated with calcium levels >14) |
|
|
What is the common tumor marker for parathyroid carcinoma? |
HCG (human chorionic gonadotropin) |
|
|
What is the treatment for parathyroid carcinoma? |
Surgical resection of parathyroid mass with ipsilateral thyroid lobectomy, ipsilateral lymph node resection |
|
|
What percentage of all cases of primary HPTH are caused by parathyroid carcinoma? |
1% |
|
|
What are the possible post-op complications after a parathyroidectomy? |
- Recurrent nerve injury (unilateral: voice change; bilateral: airway obstruction) - Neck hematoma (open at bedside if breathing is compromised) - Hypocalcemia - Superior laryngeal nerve injury |
