Ch 6 Parathyroid

Question 1

What are the parathyroid glands? How many are there?

Answer 1

-Endocrine glands
-4 of them

Question 2

Where are the parathyroid glands?

Answer 2

2 superior:
-posterior to mid/upper thyroid

2 inferior:
-variable, m/c posterior or inferior to lower thyroid

Question 3

What is the function of the parathyroid glands?

Answer 3

To produce parathyroid hormone (PTH)

Question 4

SF of parathyroid glands?

Answer 4

-Oval/almond shape
-Homogeneous
-Isoechoic to thyroid
-Measures up to 5mm (5 x 3 x 1mm)
-Hard to see normal ones on u/s (due to size, variable location + echogenicity)

Question 5

What is primary source of production of the PTH?

Answer 5

Chief cells of the parathyroid

Question 6

What does PTH do?

Answer 6

Regulates blood calcium + phosphorus levels

(calcium in the blood, not bones)

Question 7

What 3 organs does the PTH directly involve?

Answer 7

Bones, kidneys, intestines

(kidneys + intestines reabsorb calcium, while bones release calcium + phosphate)

Question 8

How does the PTH function as a feedback loop?

Answer 8

-Increase in calcium prevents further PTH secretion

-When blood calcium levels are low, PTH secretion increases to enhance calcium absorption

Question 9

PTH ___ calcium levels + ____ phosphorus levels?

Answer 9

Increases, decreases

Question 10

Where should we focus our attention to when looking for parathyroid glands?

Answer 10

Concentrate on the region b/w the posterior/medial thyroid, longus colli muscle + inferior to thyroid

Question 11

List 3 parathyroid anatomic variations?

Answer 11

-Supernumerary accessory glands
-Absence of 1 or more PTG
-Ectopic location (intrathyroidal)

Question 12

The 2 superior or inferior parathyroid glands are m/c ectopic?

Answer 12

Inferior

Question 13

What is the m/c ectopic location for the inferior parathyroid glands?

Answer 13

The anterior mediastinum

Question 14

Are ectopic parathyroid glands m/c symmetrical or asymmetrical?

Answer 14

Symmetrical

Question 15

What 2 structures often mimic parathyroid glands?

Answer 15

-Veins (use CD to confirm)
-Esophagus (turn into SAG to confirm)

Question 16

What kind of lab tests are done for the parathyroid glands?

Answer 16

Typically a fasting blood test for PTH + calcium levels

Question 17

When would elevated PTH occur?

Answer 17

-Chronic renal failure
-Hyperparathyroidism
-Vitamin D deficiency

Question 18

When would decreased PTH occur?

Answer 18

-Autoimmune destruction or congenital absence of the parathyroid glands
-Hypoparathyroidism
-Removal of the parathyroid glands
-Metastatic bone tumors

Question 19

What is hypercalcemia?

Answer 19

Excessive serum calcium levels

Due to:
-Hyperparathyroidism (m/c)
-Calcium resorption with bone mets
-Sarcoidosis
-Excess vitamin D

Question 20

What is the m/c cause of hypercalcemia?

Answer 20

Hyperparathyroidism

Question 21

What is hypocalcemia?

Answer 21

Low serum calcium levels

Due to:
-Hypoparathyroidism (m/c)
-Unintentional removal of all parathyroid glands
-Congenital absence or atrophy of PTGs

Question 22

What is the m/c cause of hypocalcemia?

Answer 22

Hypoparathyroidism

Question 23

Is hypo or hypercalcemia worse?

Answer 23

Hypocalcemia is worse as symptoms can range from mild to life threatening

Question 24

What is hyperparathyroidism?

Answer 24

Elevated secretion of PTH

Question 25

Is primary or secondary hyperparathyroidism one of the m/c endocrine disorders?

Answer 25

Primary

Question 26

What are the 2 m/c primary causes of hyperparathyroidism?

Answer 26

-Single parathyroid adenoma (m/c) + parathyroid hyperplasia (2nd m/c)
-Other causes due to parathyroid carcinoma, but this is uncommon (1%)

(hyperparathyroidism = due to spontaneous overproduction of PTH by 1 or more glands)

Question 27

What causes secondary hyperparathyroidism?

Answer 27

Secondary compensatory enlargement + hypersecretion (m/c affects all PTGs) in pt’s with chronic renal insufficiency or vitamin D deficiency (a response to a condition that is causing hypocalcemia)

Question 28

Is tertiary hyperparathyroidism common? When does it occur?

Answer 28

-Uncommon
-Occurs after long standing secondary

Question 29

Is primary hyperparathyroidism m/c in males or females?

Answer 29

Females, aged 40-60

Question 30

What would lab tests indicate in someone who has primary hyperparathyroidism?

Answer 30

Increased serum calcium levels + increased PTH levels

Question 31

How can primary hyperparathyroidism be treated?

Answer 31

Surgery

Question 32

Symptoms of primary hyperparathyroidism?

Answer 32

-Painful bones (due to increased calcium)
-Renal stones
-Abdominal groans (bowel issues)
-Psychic moans (ex. depression)
-Weight loss/anorexia

Question 33

SF of a parathyroid adenoma?

Answer 33

M/c:
-Solitary
-Oval shaped (round or teardrop shape is l/c)
-Hypoechoic (can appear completely cystic if it is so hypoechoic)
-Homogeneous
-Solid (can have internal cystic parts, is rare)
-Hypervascular (may have vascular arc)
-Average is 0.8-1.5cm in length, but can reach up to 5cm
-Can involve any 4 parathyroid glands, but m/c is the typical locations, not ectopic

Question 34

What is a parathyroid adenoma?

Answer 34

Benign tumor in parathyroid gland

Question 35

What is parathyroid hyperplasia?

Answer 35

Enlargement of all 4 PTGs (m/c unequal + asymmetric with sparing of 1 or 2 glands)

Question 36

When would parathyroid hyperplasia occur?

Answer 36

Sporadically or associated with MEN syndromes

Question 37

How can we differentiate a parathyroid adenoma from hyperplasia?

Answer 37

Solitary nodule seen = think adenoma
Multiple nodules seen = think hyperplasia

Question 38

SF of parathyroid carcinoma?

Answer 38

-Lobular contour
-Heterogeneous
-Internal cystic parts
-Usually measures >2cm

Question 39

What is parathyroid carcinoma?

Answer 39

-A functioning tumor in PTG (uncommon)
-Is slow growing
-Occurs equally in males + females aged 30-60

Question 40

Treatment for parathyroid carcinoma?

Answer 40

Surgical resection

(note: recurrence occurs in 1/3rd of cases + mets occurs in 1/3rd of cases as well)