Lecture 11 - Calcium and Vitamin D

Question 1

How does the parathyroid play a role in calcium and vitamin D homeostatsis?

Answer 1

Parathyroid secretes parathyroid hormone when it senses low Ca2+

this parathyroid hormone converts 25, Vit D to 1,25 Vit D

Question 2

How do you correct calcium?

Answer 2

Measured calcium + 0.8(4-albumin)

normal albumin is 4

you’re doing this because when you measure calcium you are only measuring the free/ionized and you need to account for how much is bound to albumin
basically if you have low calcium correct for the low albumin

Question 3

What are the physiological causes of hypocalcemia?

Answer 3

failure to secrete PTH 
resistance to PTH 
failure to produce 1,25 Vit D 
Resistance to 1,25 vit D 
calcium complexation or deposition

Question 4

Albright’s hereditary osteodystrophy

Answer 4

autosomal dominant pseudohypoparathyroidism

resistance to PTH

short stature 
short neck 
short digits (brachydactylyl)
round face

Question 5

Chvostek’s sign

Answer 5

see with hypocalcemia

when you tap the facial nerve there is twitching

Question 6

Trousseau’s sign

Answer 6

seen with hypocalcemia

inflate the BP cuff 20 mmHg above systolic BP and wait 3 minutes – you’ll see carpospasm

Question 7

What are the signs and sxs of hypercalcemia?

Answer 7

Bones

• osteoporosis
• arthritis
• osteitis fibrosa

Stones (renal)

• kidney stones
• polyuria

Moans (CNS)

• lethargy
• depression
• psychosis
• stupor
• coma

Groans (GI)

• constipation
• N/V

Question 8

Which test will help you narrow you differential dx for a pt with hyperglycemia?

Answer 8

serum parathyroid hormone (PTH)

Question 9

Hypercalcemia can be split into two main categories, what are they?

Answer 9

PTH dependent or PTH independent

dependent:
- primary
- familial hypercalemia hypocalciuria
- lithium use

independent:
- malignancy
- medications- thiazide diuretics, vitamin A intoxication, vitamin D intoxication
- hyperthyoridism
- renale failure

Question 10

What is the most common form of primary hyperparathyroidism?

Answer 10

adenoma (85% - one gland)

Question 11

Who gets hyperparathyroid surgery?

Answer 11

<50 y/o
very high calcium level >11.5
symptomatic - kidney stone
decreased bone density

Question 12

What is the pathway of vitamin D?

Answer 12

sun activates it in the skin before it goes to the liver where it meets up with other vitamin D from the diet
then it goes to the kidney where it changes from 25, D to 1,25D before going to the bone and intestines

in the intestine it increases calcium and phosphorus absorption

in the bone in mobilizes calcium stores

Question 13

Secondary hyperparathyroidism commonly caused by?

Answer 13

low vitamin D –stimulating high PTH

Question 14

What decreases your ability to make vitamin D?

Answer 14

old age
darker skin
living where there isn’t much sun

Question 15

When is vitamin D toxicity?

Answer 15

hypercalcemia

d/t sxs: nausea, dehydration, and lethargy

> 40,000 IU/day

Question 16

What three hormones regulate calcium levels?

Answer 16

Parathyroid hormone
calcitirol

calcintonin

Question 17

What does PTH do to phosphate?

Answer 17

inhibit its reabsorption

Question 18

Primary hyperparathyroidism

Answer 18

typically presents asymptomatic on labs with hypercalcemia

MC cause is adenoma (80%)
15% hyperplasia

Question 19

How can you distinguish parathyroid adenoma from hyperplasia?

Answer 19

Technetium sestamibi scan

focal retention = adenoma

Question 20

For primary parathyroidism, who gets parathyroidectomy?

Answer 20

Guidelines if they meet the follow criteria:

• <50 years
• serum Ca2+ >1mg/dl above UNL
• T score

Question 21

If a pt with primary parathyroidism can’t get surgery, what can you give them to lower their calcium?

Answer 21

calcimimetic (cinacalcet)

you’ll also give them bisphosphonate to improve bone mineral density

Question 22

Secondary hyperparathyroidism

Answer 22

increase PTH d/t hypocalcemia or vitamin D deficiency

Chronic kidney failure is the MC cause of secondary
-kidneys convert vitamin D to its active form

Question 23

What is the triad for primary hyperparathyroidism?

Answer 23

hypercalcemia
increase PTH
decrease phosphate

Question 24

What is the triad for hypoparathyroidism?

Answer 24

hypocalcemia
decrease PTH
increase phosphate

Question 25

What is the treatment for hypoarathyroidism?

Answer 25

calcium supplementation

vitamin D

Question 26

Signs of hypercalcemia

Answer 26

STONES
kidney stones
polyuria

BONES
osteoporosis
arthritis

GROANS (abdominal)
constipation
N/V

MOANS (psych)
lethargy 
depression
psychosis
stupor
coma

Question 27

What is the most common cause of hypercalcemia?

Answer 27

hyperparathyroidism

Question 28

What are the causes of hypoparathyroidism?

Answer 28

RARE

postsurgical
autoimmune

Question 29

Hypocalcemia with increased PTH

Answer 29

chronic renal dz

vitamin D deficiency

Question 30

Clinical features of hypocalcemia

Answer 30

Neuromuscular excitability 
paresthesias 
seizures
tetany 
carpospasm 
Chvotek's sign (facial nerve twitch) 
Trousseau's sign (carbal spasm to BP cuff) 

prolonged QT interval

Question 31

After you identify someone as having hypercalcemia, what do you do next?

Answer 31

determine if its because of PTH or not, check serum PTH

if high PTH –primary parathyroidism

if low PTH - malignancy secreting PTH-related hormone (apparently not detected as PTH on serum lab test)

Question 32

What is the most common cause of hypercalcemia?

Answer 32

primary hyperparathyroidism

and the MC cause of primary hyperparathyroidism is adenoma

Question 33

What is the treatment for hypocalcemia?

Answer 33

Severe:
-calcium gluconate IV

Mild:
-PO calcium + Vit D
(Calcitriol + Ergocalciferol)

Question 34

What is the treatment for hypercalcemia?

Answer 34

severe:
- IV saline + furosemide (lasix)

mild:
- none