Ch 6 Parathyroid Flashcards
What are the parathyroid glands? How many are there?
-Endocrine glands
-4 of them
Where are the parathyroid glands?
2 superior:
-posterior to mid/upper thyroid
2 inferior:
-variable, m/c posterior or inferior to lower thyroid
What is the function of the parathyroid glands?
To produce parathyroid hormone (PTH)
SF of parathyroid glands?
-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)
What is primary source of production of the PTH?
Chief cells of the parathyroid
What does PTH do?
Regulates blood calcium + phosphorus levels
(calcium in the blood, not bones)
What 3 organs does the PTH directly involve?
Bones, kidneys, intestines
(kidneys + intestines reabsorb calcium, while bones release calcium + phosphate)
How does the PTH function as a feedback loop?
-Increase in calcium prevents further PTH secretion
-When blood calcium levels are low, PTH secretion increases to enhance calcium absorption
PTH ___ calcium levels + ____ phosphorus levels?
Increases, decreases
Where should we focus our attention to when looking for parathyroid glands?
Concentrate on the region b/w the posterior/medial thyroid, longus colli muscle + inferior to thyroid
List 3 parathyroid anatomic variations?
-Supernumerary accessory glands
-Absence of 1 or more PTG
-Ectopic location (intrathyroidal)
The 2 superior or inferior parathyroid glands are m/c ectopic?
Inferior
What is the m/c ectopic location for the inferior parathyroid glands?
The anterior mediastinum
Are ectopic parathyroid glands m/c symmetrical or asymmetrical?
Symmetrical
What 2 structures often mimic parathyroid glands?
-Veins (use CD to confirm)
-Esophagus (turn into SAG to confirm)
What kind of lab tests are done for the parathyroid glands?
Typically a fasting blood test for PTH + calcium levels
When would elevated PTH occur?
-Chronic renal failure
-Hyperparathyroidism
-Vitamin D deficiency
When would decreased PTH occur?
-Autoimmune destruction or congenital absence of the parathyroid glands
-Hypoparathyroidism
-Removal of the parathyroid glands
-Metastatic bone tumors
What is hypercalcemia?
Excessive serum calcium levels
Due to:
-Hyperparathyroidism (m/c)
-Calcium resorption with bone mets
-Sarcoidosis
-Excess vitamin D
What is the m/c cause of hypercalcemia?
Hyperparathyroidism
What is hypocalcemia?
Low serum calcium levels
Due to:
-Hypoparathyroidism (m/c)
-Unintentional removal of all parathyroid glands
-Congenital absence or atrophy of PTGs
What is the m/c cause of hypocalcemia?
Hypoparathyroidism
Is hypo or hypercalcemia worse?
Hypocalcemia is worse as symptoms can range from mild to life threatening
What is hyperparathyroidism?
Elevated secretion of PTH
Is primary or secondary hyperparathyroidism one of the m/c endocrine disorders?
Primary
What are the 2 m/c primary causes of hyperparathyroidism?
-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)
What causes secondary hyperparathyroidism?
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)
Is tertiary hyperparathyroidism common? When does it occur?
-Uncommon
-Occurs after long standing secondary
Is primary hyperparathyroidism m/c in males or females?
Females, aged 40-60
What would lab tests indicate in someone who has primary hyperparathyroidism?
Increased serum calcium levels + increased PTH levels
How can primary hyperparathyroidism be treated?
Surgery
Symptoms of primary hyperparathyroidism?
-Painful bones (due to increased calcium)
-Renal stones
-Abdominal groans (bowel issues)
-Psychic moans (ex. depression)
-Weight loss/anorexia
SF of a parathyroid adenoma?
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
What is a parathyroid adenoma?
Benign tumor in parathyroid gland
What is parathyroid hyperplasia?
Enlargement of all 4 PTGs (m/c unequal + asymmetric with sparing of 1 or 2 glands)
When would parathyroid hyperplasia occur?
Sporadically or associated with MEN syndromes
How can we differentiate a parathyroid adenoma from hyperplasia?
Solitary nodule seen = think adenoma
Multiple nodules seen = think hyperplasia
SF of parathyroid carcinoma?
-Lobular contour
-Heterogeneous
-Internal cystic parts
-Usually measures >2cm
What is parathyroid carcinoma?
-A functioning tumor in PTG (uncommon)
-Is slow growing
-Occurs equally in males + females aged 30-60
Treatment for parathyroid carcinoma?
Surgical resection
(note: recurrence occurs in 1/3rd of cases + mets occurs in 1/3rd of cases as well)
