Week 10: Chp 40: Parathyroid Gland

Question 1

Where are parathyroid glands found?

Answer 1

embedded in the thyroid gland

Question 2

What hormone does the parathyroid gland secrete?

Answer 2

Parathyroid hormone (PTH)

Question 3

What does Parathyroid Hormone Control or Regulate?

Answer 3

Calcium homeostasis

-target tissues of PTH: bones, kidneys, intestines

Question 4

Parathyroid Hormone (PTH) is Secreted in response to what?

Answer 4

to low serum calcium levels

Question 5

What are the target tissues of PTH?

Answer 5

bones, kidneys, and intestines

Question 6

Parathyroid Hormone increases serum calcium through the following actions:

Answer 6

-increased bone resorption through osteoclastic activity (stimulates Ca release from bones)
-stimulates renal absorption of calcium (stimulates Ca uptake in kidneys)
-stimulates activation of vitamin D, which increases intestinal reabsorption of calcium (stimulates Ca uptake in intestines)
>blood Ca levels rise

Question 7

Parathyroid Hormone also affects phosphorus levels through the following actions:

Answer 7

• reduces the reabsorption of phosphorus from the proximal tubes in the kidneys, leading to a decrease in serum phosphorus levels
• increases bone resorption, leading to an increase in phosphorus release from bone
• increases small intestine absorption of phosphorus

Question 8

What also has a role in regulating Calcium besides PTH?

Answer 8

Thyrocalcitonin (calcitonin), which is secreted from the thyroid gland and lowers calcium levels
-serum calcium and phosphorus levels are lowered by the actions of calcitonin on the bones; Bone resorption is a process involving breakdown of bone through osteoclastic activity that involves secretion of enzymes and acid that dissolve microscopic bits of bone matrix
>because osteoclastic activity is decreased by calcitonin, there is less calcium released from the bone into the circulation; when calcium levels are low calcitonin secretion is inhibited, when calcium levels are high calcitonin is increased

Question 9

Bone resorption

Answer 9

process involving breakdown of bone through osteoclastic activity that involves secretion of enzymes and acid that dissolve microscopic bits of bone matrix

Question 10

Parathyroid Gland Laboratory Values

Answer 10

• PTH: 10-65 pg/mL
• Magnesium: 1.6-2.6 mg/dL
• Vitamin D: 20-100 ng/dL
• Calcium: 8.2-10.2 mg/dL
• Ionized Calcium: 4.6-5.3 mg/dL
• Phosphorus: 2.5-4.5 mg/dL

Question 11

Lab Values: PTH

Answer 11

10-65 pg/mL

-increased in hypoparathyroidism

Question 12

Lab Values: Magnesium

Answer 12

1. 6-2.6 mg/dL

- decreased in hypoparathyroidism

Question 13

Lab Values: Vitamin D

Answer 13

20-100 ng/dL

• decreased in hypoparathyroidism
• variable in hyperparathyroidism

Question 14

Lab Values: Calcium

Answer 14

8. 2-10.2 mg/dL
   - decreased in hypoparathyroidism
   - increased in hyperparathyroidism
   - decreased by thyrocalcitonin from thyroid gland

Question 15

Lab Values: Ionized Calcium

Answer 15

4. 6-5.3 mg/dL
   - decreased in hypoparathyroidism
   - increased in hyperparathyroidism

Question 16

Lab Values: Phosphorous

Answer 16

2. 5-4.5 mg/dL
   - increased in hypoparathyroidism
   - decreased in hyperparathyroidism