Calcium metabolism Flashcards Preview

STEP1 > Calcium metabolism > Flashcards

Flashcards in Calcium metabolism Deck (31):
1

What is the explanation for hypercalcemia 90% of the time?

1. Primary hyperparathyroidism
2. malignancy-secreting PTHrP

2

What is the most common form of primary hyperparathyroidism, producing hypercalcemia?

parathyroid adenoma

3

What is the second most common form of primary hyperparathyroidism?

parathyroid hyperplasia

4

Which types of malignancies can cause secretion of PTHrP and hypercalcemia?

small cell cancer (esp of lung)
renal cell carcinoma
breast mets to lung
multiple myeloma

5

10% of the time, what is the reason for hypercalcemia?

lots of Vit D ingested
lots of Ca++ ingested
Granulomas: macrophages activate Vit D. THink TB, sarcoidosis
Increased bone turnover
Thiazide diuretics

6

Which types of things can cause increased bone turnover--leading to hypercalcemia?

hyperthyroidism
Vit A intoxication
immobilization

7

Which diuretics increase calcium in blood, which decrease it?

Loops lose calcium. Thiazides retain it.

8

What are the signs/symptoms of hypercalcemia/hyperparathyroidism?

Stones, Bones, Groans, Psychiatric Overtones

9

What types of stones are produced by hypercalcemia?

Kidney stones (ca++)
nephrocalcinosis
polyuria, polydipsia
uremia

10

What types of bone issues do you see with hypercalcemia?

osteoporosis
osteitis fibrosa cystica
osteoarthritis

11

What are the features of osteitis fibrosa cystica?

subperiosteal bone respiration of the radial aspect of the middle phalanges
tapering of the distal clavicle
salt and pepper skull
bone cysts
brown tumors of the long bones

12

What are the abdominal groans of hypercalcemia?

constipation
N/V
peptic ulcers (increase in Ca++ causes an increase in gastrin)
pancreatitis

13

What are the psychiatric overtones of hypercalcemia?

lethargy
depression
psychosis
confusion, stupor, coma

14

What are other random features of hypercalcemia?

proximal muscle weakness
keratitis/conjunctivitis
HTN
itching

15

Which cells make parathyroid hormones?

chief/principal cells of parathyroid gland

16

What do the oxyphil cells of the parathyroid gland do?

no one knows!
they are packed with mitochondria, show up at puberty, and increase w/ age.

17

How does PTH stimulate bone turnover?

stimulates osteoblasts. They release RANKL that stimulates osteoclasts

18

Which carcinoma causes increased calcitonin?

medullary thyroid carcinoma
**not reactive to radioactive iodine treatments
C cells of thyroid aka parafollicular cells secrete calcitonin

19

What is the nerve supply to the parathyroid gland?

cervical sympathetic ganglion
controls blood flow, but not stimulation

20

What are the general causes of hypocalcemia?

Hypoparathyroidism
Vit D deficiency
acute pancreatitis

21

What are some common causes of hypoparathyroidism?

parathyroidectomy
autoimmune
pseudohypoparathyroidism (kidney doesn't respond to PTH)
Di George Syndrome

22

Why does acute pancreatitis lead to hypocalcemia?

don't get those fats dealt w/ w/o pancreatic secretions. Ca++ in gut combines w/ fatty acids-->soaps

23

Chovstek and Trouseau signs are seen w/ hypo or hypercalcemia?

hypocalcemia

24

What is a type of pseudohypoparathyroidism?

Type 1a: Albright Hereditary Osteodystrophy

25

What are the special features of Albright Hereditary Osteodystrophy?

short stature and obesity
underdeveloped 3rd and 4th phalanges
osteitis fibrosa cystica

26

Where are Ca++ and PO4 reabsorbed in the kidney?

Ca++-->DCT
PO4-->PCT

27

Describe the relationship b/w magnesium and PTH secretion?

Low Mg++ -->PTH secretion
Super Low Mg-->Decreased PTH secretion

28

What are some causes of low magnesium?

Maggie and her DADA
diarrhea
aminoglycosides
diuretics
alcohol

29

High PTH, High Ca++, Low phosphate...cause of hyperparathyroidism?

Primary hyperparathyroidism
most likely parathyroid adenoma

30

high PTH, Low Ca++, High phosphate...cause of hyperparathyroidism?

Secondary hyperparathyroidism
chronic renal failure, can't reabsorb anymore!

*can also be caused by Vit D deficiency-may get rickets

31

What would the lab values and cause be for tertiary hyperparathyroidisM?

refractory chronic renal failure
parathyroid hyperplasia finally leads to a gland that secretes its own stuff constantly
High PTH, High Ca++