Hyperparathyroidism and Hypocalcemia Flashcards Preview

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Flashcards in Hyperparathyroidism and Hypocalcemia Deck (22):
1

PTH secretion from

Chief cells

2

What percent of total body calcium is stored in the bone?

about 99%

3

Of the 1% of total body calcium that is not in the bone, what part of the serum calcium is protein bound?

40% (mainly to albumin)
10% complexed with anions
50% free ionized

4

Low calcium levels elicit the release of PTH from the parathyroid glands, what are the fast responses to this low calcium? Slow?

Fast: Increased bone resorption (calcium mobilization from bone), decreased phosphate reabsorption by inhibiting the Na/Pi cotransport in the PCT, Increased calcium rebsorption from the DCT.

Slow: Upregulates 1 alpha hydroxylase in the kidney which activates vitamin D to 1, 25 vit D3 which leads to increased calcium absorption in the gut.

5

85% of primary hyperparathyroidism is due to what?

Adenoma, the other 15% is due to hyperplasia

6

The three causes of PTH dependent hypercalcemia

Hyperparathyroidism
Familial Hypocaciuric Hypercalcemia
Li/HCTZ

7

WHat is the deal with PTH independent Hypercalcemia?

Bad news usually,
Generally due to metastatic cancer (osteolytic bone metastasis), Vitamin D toxicity, Immobilization, Drugs (thiazide diuretics),

8

Bones, stones, moans, groans

primary hyperparathyroidism

9

What is the mutation in familial hypocalciuria hypercalcemia

Autosomal dominant CaSR inactivating mutation.

10

FHH is generally benign...

truth.
Calcium may be mildly elevated and PTH may be mildly elevated.

Penetrance is 100%. Everybody in the family will have it!!

WHY LOW CALCIUM IN THE URINE? Because the mutated receptor is also present in the kidneys, therefore they think that there is not much calcium in the blood and don't excrete calcium

11

Parathyroid adenomas are more common in

WOMEN

12

Secondary hyperparathyroidism is caused by?

Any condition that is associated with chronic depression in the serum calcium level thus leading to overactivity of the parathyroids.

The parathyroids are working fine.

13

Most common cause of secondary parathyroidism is

renal failure

14

Why does renal failure cause low calcium

renal failure means less phosphate excretion leading to high serum phosphate--> phosphate binds calcium with high affinity so you have a lower conc of free ionized calcium

ALSO ...less vitamin D being activated since the kidney isn't working so the gut isn't absorbing the calcium as well.

15

Hypercalcemia of malignancy most commonly caused by

Breast or squamous cell lung cancer (can be any cancer)

16

Granulomatous disorders are also a cause of hypercalcemia with low PTH. Examples of such disorders are:

Sarcoidosis, lymphoma

Mech: the T-cells contain 1 alpha hydroxylase, this jacks up vit D3 which leads to high calcium absorption

17

What multiplie Endocrine neoplasm syndromes can hyperparathyroidism be associated with>

MEN 2A and MEN 1

18

What are the clinical symptoms of hyperrarathyroidism

Stones, Groans (abdominal), moans (psychic), bones

19

What kinds of work-up would you want to do on a pt with potential hyperparathyroidism?

- Look at calcium levels and Albumin levels
- PTH
- 25 OH Vitamin D
- 24 hour urine calcium to differentiate from familial hypocalciuric hypercacemia

20

How do you manage Primary HPT in a pt with osteoporosis

Bisphosphonates

21

What is the mechanism of granulomatous disease causing hypercalcemia

Activate alpha 1 hydroxylase in these tissues

22

Hypocalcemic pt. What do you replace first?

Magnesium actually *unless they just had a thyroidectomy,

Low magnesium is usually contributing to the low PTH