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Flashcards in Nephro - Calcium - Online MedEd Deck (38):
1

Pathophysiology of calcium...

Parathyroid glands behind the thyroid
-Have cells that have packaged parathyroid hormones in vesicles
-There is a calcium sensing receptor, which is inhibitory. If Calcium rises, then calcium turns OFF release of PTH
-Calcium level, PTH released
-PTH is primary way body manages Calcium

2

What are the effects of PTH?

3 different organ systems
1) Bone - cause resorption of bone (osteoclasts clear bone... release minerals) - elevation of Ca and Phos
2) Kidney - turns on 1,25-vitamin D --> turns on absorption of calcium in gut - resorption of calcium and excretion of phosphorus. There is also creation of vitamin D which goes to the gut
3) Gut (indirect) - activated by 1,25 vitamin D --> absorption of both calcium and phosphorus
** If kidney is working, kidney always wins = so too much PTH --> calcium elevate, and phosphorus falls!

3

What is another system that can effect PTH?

1,25 vitamin D secreted from granulomas such as TB/sarcoid --> which can activate the same 3 organ systems

4

Most calcium is bound to what?

Albumin
About 1% is free ionized calcium
Normal albumin is 4
Normal calcium is 10
-If albumin changes by 1, then calcium changes by 0.8 in same direction. So Albumin of 3, means calcium of 9.2
-Albumin is typically low

5

Most calcium disorders can be determined by checking 3 things

Ca
Phos
PTH
Sometimes check vitamin D level

6

Hypocalcemia - presentation

Tetany
Perioral tingling
Trousseau sign - inflate BP cuff, induce latent tetany
Chvostek's sign - tap facial nerve, side of face will contract

7

What should you do if you see hypocalcemia on labs?

Check albumin
-Corrects with albumin
-Not a deficiency of calcium
-Just a product of albumin

8

If hypocalcemia and albumin does not correct... need to check ionized calcium (this is in the absence of signs of hypocalcemia)

If ionized calcium is low
How to give calcium? IV calcium gluconate/carbonate

9

Management of hypocalcemia

Give IV calcium (gluconate/carbonate)

10

Hypercalcemia - presentation

Kidneys stones
Psychic moans
Abdominal moans
Painful bones
*Needs treatment!

11

Don't have symptoms of hypercalcemia... what to do?

Recheck calcium
If recheck shows elevated calcium, then treat. If normal, then stop

12

Treatment of hypercalcemia

If asymptomatic --> diagnose
If symptomatic --> needs treatment first
Treatment used to be fluid and lasix. Lasix blocks the paracellular calcium absorption in ascending loop of henle --> calciuria
*Loop diuretic/lasix actually has been found to drive the fluid out/drain and cause calcium to be concentrated
***So main treatment of hypercalcemia = VOLUME (lots of fluids). IV fluids!!

13

Treatment of hypercalcemia - 3 phases

1) Intermediate phase - calcitonin (IV - calcium "tone down")
2) Long term phase - bisphosphonates (standard)**
3) Indeterminate phase - loop diuretics (only give when volume up)
*So most importantly is fluids and bisphosphonates

14

So persistent hypercalcemia but no symptoms... differential

1) Hyperparathyroidism

15

Hyperparathyroidism - 3 categories

1) Primary - autonomous secretion - from a single gland, generally noncancerous
2) Secondary - product of early renal failure, this is an appropriate response to relative hypocalcemia
3) Tertiary - also autonomous (multiple adenomas)

16

Hyperparathyroidism - presentation

Hypercalcemia
Pathologic fractures - decreased bone density
Brown tumours (not malignancy) that eat away bone

17

Dx of hyperparathyroidism

Elevated PTH, Elevated Ca, Low Phos
Inappropriate elevation of PTH --> kidney wins, so calcium goes up and phos goes down --> calcium does not turn off PTH
*Do not need vitamin D
Due to autonomous production of PTH from gland

18

How to differentiate primary, secondary, and tertiary?

Get sestamibi scan
There are 4 parathyroid glands. If primary --> will get 1 gland with adenoma making PTH regardless of Ca. Other parathyroid glands are atrophied/suppressed by elevated Ca
Tertiary hyperparathyroidism --> multiple areas/adenomas that secrete PTH

19

Tertiary hyperparathyroidism

Chronic low Ca due to inability to make vita D --> up regulate PTH appropriate --> constant stimulation of glands --> multiple areas that secrete PTH

20

Treatment of hyperparathyroidism

Is surgical resection
And hypoparathyroidism because the other glands have atrophied
Cinacalcet (calcium mimetic agent) is used in CKD to prevent tertiary hyperparathyroidism --> to prevent the amount of PTH made

21

Hypercalcemia associated with malignancy - pathophys

Cancer can either...
1) Mets - invades bone - causes a release of calcium and phosphorus --> this inhibits PTH release --> so PTH is low (kidney can't win... no PTH to stimulate the kidney... so Phos will be high as well as calcium)
2) Paraneoplastic syndrome - secrete PTH-related peptide (PTHrP) this is in squamous cell carcinoma of the lungs

22

Tumour invasion/cancer leads to what values on labs?

Elevated calcium and phos
Low PTH

23

PTHrP with SCC lungs - what values on labs?

This is PTH
So kidney is working and kidney wins
Elevated Calcium, Low Phos
Natural parathyroid glands are working --> so PTH is LOW
-Now measure PTHrP on labs!

24

Difference between mets and PTHrP on labs

Phosphorus

25

Hypervitaminosis D - how to get this?

Over-ingested vitamin D (uncommon)
Granulomatous disease - excess vitamin completed vitamin D (1,25) is made
With lots of vitamin D, will absorb calcium and phos from gut. Because glands are working, Ca will inhibit PTH from glands.

26

Labs on hypervitaminosis D/granulomatous disease?

Elevated Ca and Phos. Low PTH
This looks a lot like Mets!
The difference - history of sarcoid, TB
Measure a 1,25 vitamin D to determine granuloma or mets

27

Hypercalcemia of immobilization

Calcium is elevated because there is immobility (i.e. maybe orthopedics/trauma)
-So PTH is low
-So kidney doesn't win
-Phos is elevated

28

Familial hypercalcemic hypocalciuria

Asymptomatic elevation of Calcium (11-12 range)
Check urine calcium... will be low
Usually asymptomatic, there is family history

29

Hypoparathyorid - differential

1) Iatrogenic - thyroid surgery, accidentally take out parathyroids as well; or parathyroid resection surgery
2) Autoimmune

30

Post-op day 1 of thyroid surgery - will see what symptoms?

Perioral tingling, tetany
Dx: Low PTH, low Ca, phosphorus is irrelevant
Treatment is IV calcium!

31

Pseudohyperparathyroidism - what is this?

End organ resistance to PTH
PTH insensitivity. As though low PTH. But PTH levels will be elevated!

32

Dx of pseudohyperparathyroidism

PTH is HIGH (PTH insensitivity)
But Calcium is low and phosphorus is low

33

Vitamin D deficiency - where does vitamin D come from

Vitamin D comes from sunshine and dairy products

34

Patients with vitamin D deficiency - will present with

Osteopenia
Dexa scan -2.0
No dairy products/stays inside all day

35

For vitamin D deficiency - what should we get?

A 25-vitamin D level
Not a 1,25 vitamin D level

36

Treatment of vitamin D deficiency

High dose PO vitamin D - if hypocalcemia is not bad, just give vitamin D
IV calcium - given for hypocalcemia
Bisphosphonates - for severe osteopenia

37

Chronic kidney disease

When Cr isn't bad, early CKD --> impairment of vitamin D formation --> secondary hyperparathyroidism (vitamin D can't absorb calcium)
Late stage CKD --> hypophosphatemia

38

Pancreatitis

Sequestration - calcium drops - ominous sign
(disorder of inflammation)