Parathyroid and calcium

Question 1

What is the name of the hormone that the parathyroid hormone synthesises and from which cells in the parathyroid gland is this secreted from?

Answer 1

Parathyroid hormone

From the chief cells

Question 2

What effect does the parathyroid have on calcium and phosphate levels and explain the effect of PT on the bones, kidneys and Gi tract

Answer 2

Increases calcium, decreases phosphate

Bones—>Increased resorption–>Increased calcium and increased phosphate
Gut- Increased Calcium absorptionby promoting formation of calcitriol in the kidneys
Kidneys: Less ca2+ excretion, increasded phosphate secretion

Question 3

Name two types of cells in the parathyroid gland and what each do and describe them

Answer 3

chief cells: produce PTh: lots of nuclei

oxyphil cells: not sure: Lots of cytoplasm

Question 4

Explain how calcitriol causes increased absoprtion of Ca2+

Answer 4

increases transcellular ptake

normally ca2+ taken up by paracellular

Question 5

where is vitamin hydroxylated to its active form?

Answer 5

kidney and liver

Question 6

How does decreasing levels of Ca2+ cause increased levels of PTH?

Answer 6

prolongs half life of RNA

Question 7

Give symptoms of hypercalcaemia

Answer 7

tired, depressed, constipation, kidneys, bone and muscle aches

Question 8

Two blood tests for hypercalcaemia?

Answer 8

Alkaline phosphatase: Enzyme on osteoplasts so increased osteoblast activity reflects increased alkaline phosphatase so increased bone turnover

Ca2+ levels

Question 9

Causes of hypercalcaemia?

Answer 9

malignant osteolytic bone metastases

Multiple myeloma

Question 10

Name 4 types of tumour that commonly metastasuse to bone?

Answer 10

breast, thyroid, renal, and lung

Question 11

what is special about prostate tumours?

Answer 11

when metastasise to bone, they are osteoblastic metastases

Question 12

6 common sites for bone metastases and why?

Answer 12

skull, proximal femur and humerus, ribs, vertebrae, pelvis

these produce a lot of blood cells so good blood supply

Question 13

Define primary hyperparathyroidism

Answer 13

1 of the 4 glands has a adenoma that secretes PTH

Question 14

Define secondary hyperparathyroidism

Answer 14

the 4 parathyroid glands have hyperplasia

Question 15

Give two causes of secondary parathyroidism and what two things can cause this case?

Answer 15

vit D deficiency

chronic kidney disease due to failure to hydroxylate VitD

Question 16

Describe the process of the effect of secondary hyperparathyroidism

Answer 16

Vit D deficiency–>less calcitriol–>less Ca2+ absorption from the gut
less Ca2+–>increased PTH secretion so increased bone resorption–>osteomalacia (if due to Vit D deficiency) or renal osteodystrophy

Question 17

pateit comes in. Raised Phosphate, low calcium, raised alkaline phosphatase, raised PTH

Answer 17

secondary

Question 18

Raised calcium, normal phosphate, raised alkaline phosphatase, low PTH

Answer 18

A malignancy causing hypercalcaemia

Question 19

Raised calcium, low phosphate, raised alkaline phosphatase and raised PTH

Answer 19

primary hyperparathyroidism

Question 20

When is hypocalcaemia seen?

Answer 20

thyroidectomy patients where parathyroid has been removed as well accidently

Question 21

Explain the difference in symtpoms for hypo and hypercalcaemia

Answer 21

Hypo- Increased excitability of neurones so increased action potential firing –>tingling, epilepsy, tetany
Hyper- Decreased excitability—>lethargy, confusion, coma

Question 22

How can hypocalcaemia kill

Answer 22

tetany of the laryngeal muscle

Question 23

What is the difference between osteomaqlacia and osteoporosis

Answer 23

osteoporosis- Same ratio of bone to matrix, just less bone there
osteomalacia- Lower ratio of bone to matrix

Question 24

Risk factors for osteoporosis? 6

Answer 24

post menopausal women
low BMI
Long term oral steroid use
heavy drinking
smoking
prolonged inactivity

Question 25

Treatment for hypercalcaemia?

Answer 25

rehydration