Parathyroid and Calcium

Question 1

How much calcium does the body contain and where is it stored?

Answer 1

1-2 kg of calcium
98% in skeleton
0.03% Plasma
0.1% ECF
1% ICF

Question 2

What forms is Plasma calcium present in?

Answer 2

50% Ionized (active form)
41% Protein bound
9% Combined with anions

Question 3

Which protein is plasma calcium mostly bound to?

Answer 3

Albumin

Question 4

Does Ca+ equilibrate between skeleton and plasma?

Answer 4

Yes, but only 0.5% of bone in calcium is readily exchangeable

Question 5

What changes can be seen in hypocalcemia?

Answer 5

1. Tetany
2. Seizures
3. Longer QT
4. Nervous system excitement

Question 6

What two tests can be done to check for hypocalcemia?

Answer 6

Carpopedal spasm (tap on wrist)
Chvosteks sign (tap facial nerve)

Question 7

What can Longer QT lead to?

Answer 7

R on T phenomenon which can turn in Torsades

Question 8

What changes can be seen with hypercalcemia?

Answer 8

1. Nervous system depression
2. Short QT
3. Long PR
4. Constipation
5. Anorexia

Question 9

What is the CHIEF manifestation of hypercalcemia?

Answer 9

Skeletal muscle weakness

Question 10

What is treatment for hypercalcemia?

Answer 10

1. Maintain Urine ouput
2. Hydrate
3. Administer Mithramycin

Question 11

How much phosphorus is contained in the body and where can it be found?

Answer 11

1kg of phosphrous
85% skeleton
15% Muscle/tissue
1% ECF

Question 12

How much phosphorous is protein bound?

Answer 12

12%

Question 13

Do phosphorous levels or calcium levels fluctuate more significantly?

Answer 13

Phosphorus; moves between ECF and bone as well as between ECF and ICF

Question 14

How does phosphorus enter the ECF?

Answer 14

via GI, ICG, bone

Question 15

How does phosphorus leave the ECF?

Answer 15

via Urine, ICF, Bone

Question 16

Where is the major control site of phosphorus?

Answer 16

Kidneys

Question 17

Why does hypophosphatemia lead to weakness?

Answer 17

ATP is built on phosphorus

Question 18

How can GI absorption of phosphorus be increased?

Answer 18

1,25 D3

Question 19

PTH increase or decrease urinary excretion of phosphorus?

Answer 19

Increases

Question 20

What two cells are mainly contained in the parathyroid glands?

Answer 20

Chief and oxyphil cells

Question 21

Which cells secrete parathyroid hormone (PTH)?

Answer 21

Chief cells

Question 22

What three things can cause enlargement of the parathyroid glands?

Answer 22

1. Prolonged stimulation
2. Pregnancy
3. Lactation

Question 23

Is the parathyroid system made of negative or positive feedback system?

Answer 23

Negative feedback system

Question 24

What is the most important hormone for calcium homeostasis?

Answer 24

Parathyroid Hormone (PTH)

Question 25

Where in the kidney is calcium reabsorbed?

Answer 25

Proximal tubules

Question 26

What is bone resorption?

Answer 26

Moving calcium from bone into blood

Question 27

What are the 4 actions of PTH?

Answer 27

1. Increases bone resorption of Ca++ and Phos
2. Increases reabsorption of Ca++ in kidney
3. Decreases reabsorption of Phophate in renal tubules
4. Increases production of 1,25 Dihydroxycholecalciferol.

Question 28

What is the major stimulus for PTH secretion?

Answer 28

Low serum Ca++ levels

Question 29

What is the most common form of calcium in the body?

Answer 29

1,25 dihydroxycholecalciferol

Question 30

Increased PTH causes what changes to calcium and phosphate?

Answer 30

Serum: Calcium up, Phosphate down

Urine: Calcium down, Phosphate Up

Question 31

What hormone opposes the effects of PTH?

Answer 31

Calcitonin

Question 32

Where is calcitonin produced?

Answer 32

Parafollicular (c cells) of the thyroid

Question 33

Increased calcitonin causes what changes to calcium and phosphate?

Answer 33

Serum: Calcium down, Phosphate down

Urine: Calcium up, Phosphate up

Question 34

What stimulus causes increased secretion of calcitonin?

Answer 34

Increased serum Ca++

Question 35

What is the name of Vit D’s active product?

Answer 35

1,25 Dihydroxycholecalciferol

Question 36

How does Vitamin D effect serum or bone calcium levels?

Answer 36

Increases calcium absorption from the GI tract.

Question 37

Where is Vitamin D3 formed?

Answer 37

Skin by exposure to sunlight

Question 38

Where is Vitamin D converted to its active form?

Answer 38

the liver

Question 39

Bone resorption of calcium is increased by ____ and inhibited by _____?

Answer 39

PTH

Calcitonin

Question 40

Hypoparathyroidism results in what?

Answer 40

1. Tetany
2. Muscle cramps
3. Grand mal seizures
4. CV collapse

Question 41

What is tx for hypoparathyroidism?

Answer 41

PTH, calcium, and Vit d supplementation

Question 42

What airway related issue can hypoparathyroidism cause?

Answer 42

Laryngospasm d/t hypocalcemia

Question 43

What other electrolyte disorder can cause calcium resistant hypocalcemia?

Answer 43

Hypomagnesemia ( treat mag first, then calcium.)

Question 44

What are signs of primary hyperparathyroidism?

Answer 44

1. Hypercalcemia
2. Hypercalciuria
3. Hypophosphatemia
4. Hyperphosphaturia
5. Bone demineralization
6. Kidney stone formation
7. Cardiac function effected with short QT, depresses relaxation).

Question 45

What is the most common cause of hyperparathyroidism?

Answer 45

Parathyroid hyperplasia and Parathyroid tumor

Question 46

What is osteomalacia?

Answer 46

Softening of bones

Question 47

Vit D deficiency in children results in what?

Answer 47

Rickets— bones fail to mineralize

Question 48

Calcium is indicated for treatment of _______ induced EKG changes because of its cell membrane stabilizing effects?

Answer 48

Hyperkalemia

Question 49

What is the Calcium Chloride to Calcium Gluconate exchange rate?

Answer 49

1g Calcium Chloride= 3g Calcium Gluconate

Question 50

Which patient is Calcium treatment contraindicated in?

Answer 50

Digoxin toxicity d/t risk of lethal arrhythmias