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Nephro > Nephro - Calcium - Online MedEd > Flashcards

Nephro - Calcium - Online MedEd Flashcards

1
Q

Pathophysiology of calcium…

A

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
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2
Q

What are the effects of PTH?

A

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!

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3
Q

What is another system that can effect PTH?

A

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

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4
Q

Most calcium is bound to what?

A 
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
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5
Q

Most calcium disorders can be determined by checking 3 things

A

Ca
Phos
PTH
Sometimes check vitamin D level

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6
Q

Hypocalcemia - presentation

A

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

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7
Q

What should you do if you see hypocalcemia on labs?

A

Check albumin

  • Corrects with albumin
  • Not a deficiency of calcium
  • Just a product of albumin
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8
Q

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

A

If ionized calcium is low

How to give calcium? IV calcium gluconate/carbonate

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9
Q

Management of hypocalcemia

A

Give IV calcium (gluconate/carbonate)

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10
Q

Hypercalcemia - presentation

A 
Kidneys stones
Psychic moans
Abdominal moans
Painful bones 
*Needs treatment!
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11
Q

Don’t have symptoms of hypercalcemia… what to do?

A

Recheck calcium

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

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12
Q

Treatment of hypercalcemia

A

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!!

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13
Q

Treatment of hypercalcemia - 3 phases

A

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

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14
Q

So persistent hypercalcemia but no symptoms… differential

A

1) Hyperparathyroidism

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15
Q

Hyperparathyroidism - 3 categories

A

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)

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16
Q

Hyperparathyroidism - presentation

A

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

17
Q

Dx of hyperparathyroidism

A

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
Q

How to differentiate primary, secondary, and tertiary?

A

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
Q

Tertiary hyperparathyroidism

A

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

20
Q

Treatment of hyperparathyroidism

A

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
Q

Hypercalcemia associated with malignancy - pathophys

A

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
Q

Tumour invasion/cancer leads to what values on labs?

A

Elevated calcium and phos

Low PTH

23
Q

PTHrP with SCC lungs - what values on labs?

A 
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
Q

Difference between mets and PTHrP on labs

A

Phosphorus

25
Q

Hypervitaminosis D - how to get this?

A

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
Q

Labs on hypervitaminosis D/granulomatous disease?

A

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
Q

Hypercalcemia of immobilization

A

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
Q

Familial hypercalcemic hypocalciuria

A

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

29
Q

Hypoparathyorid - differential

A

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

30
Q

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

A

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

31
Q

Pseudohyperparathyroidism - what is this?

A

End organ resistance to PTH

PTH insensitivity. As though low PTH. But PTH levels will be elevated!

32
Q

Dx of pseudohyperparathyroidism

A

PTH is HIGH (PTH insensitivity)

But Calcium is low and phosphorus is low

33
Q

Vitamin D deficiency - where does vitamin D come from

A

Vitamin D comes from sunshine and dairy products

34
Q

Patients with vitamin D deficiency - will present with

A

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

35
Q

For vitamin D deficiency - what should we get?

A

A 25-vitamin D level

Not a 1,25 vitamin D level

36
Q

Treatment of vitamin D deficiency

A

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

37
Q

Chronic kidney disease

A

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
Q

Pancreatitis

A

Sequestration - calcium drops - ominous sign

disorder of inflammation

Nephro (8 decks)

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