Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
49 Cards in this Set
- Front
- Back
|
__% of the body's calcium is in bone, and __% is in plasma |
99% in bone
1% in plasma |
|
|
Calcium occurs in plasma in these three forms:
Which form is the biologically active form? |
Ionized (50%) |
|
|
How does acidosis affect plasma calcium level?
|
Acidosis causes hypercalcemia.
Hydrogen and calcium bind albumin competitively, thus when H+ is increased, Ca2+ is liberated from albumin. |
|
|
How would a decrease in albumin affect calcium concentration?
|
It would cause a decrease in bound Ca and total Ca. Free Ca2+ would not be affected.
|
|
|
Calcium salts are excreted by the kidney (T/F)
|
True; they are filtered and cannot be reabsorbed |
|
|
This enzyme converts 25(OH) vitamin D to 1,25-dihydroxy-vitamin D
|
1-alpha-hydroxylase
|
|
|
This enzyme converts Vitamin D3 to 25-hydroxy-vitamin D
|
25-hydroxylase
|
|
|
Which molecule is converted by light energy to Vitamin D3?
|
7-Dehydrocholesterol
|
|
|
Scientific name for the active form of Vitamin D
|
1,25-dihydroxycholecalciferol
|
|
|
Physiologic function of Vitamin D/DHCC
|
Allows transmembrane proteins in the intestine and PCT to absorb calcium Ca(2+) and PO4(3-)
|
|
|
Active vitamin D deficiency causes ____ in children and ____ in adults |
Rickets (children) and Osteomalacia (adults)
|
|
|
What stimulates the parathyroid glands to secrete PTH?
|
Decreased free (ionized) calcium concentration |
|
|
How does PTH affect:
Bone Nephron PCT Digestion |
Bone: enhances osteoclast activity, resulting in release of ionized calcium and phsophate |
|
|
Increased PTH (increases/decreases) the production of 1,25-dihydroxycholecalciferol
|
Increase; body needs more active vitamin D to absorb calcium in the GI tract
|
|
|
Site of production of calcitonin
|
Parafollicular or C-cells of the thyroid gland
|
|
|
what stimulates the production of calcitonin?
|
Increased plasma Ca concentration
|
|
|
What are the physiologic effects of calcitonin?
|
Inhibits osteoclast activity in bone and increased excretion/decreased reabsorption of Ca in the kidney
|
|
|
Symptoms of hypercalcemia include:
|
GI symptoms
Neurologic changes Kidney stones Osteopenia Coma (extreme) |
|
|
Most frequent cause of hypercalcemia
other causes? |
Primary hyperparathyroidism
Other: malignancy, sarcoidosis, Vitamin D overdose, immobilization |
|
|
Symptoms of hypocalcemia
|
Tetany, spasms and convulsions
|
|
|
What are symptoms of primary parahyperthyroidism?
|
Thin bones, increased risk of fracture, altered mental status and kidney stones
|
|
|
Lab results of primary hyperparathyroidism
|
Increased: calcium (serum and urine), ALP (bone), phosphate (urine), PTH |
|
|
How does ectopic PTHrP cause hypercalcemia?
|
PTH related protein (PTHrP) is similar to the N-terminal of PTH and has the same physiologic effect on osteoclasts, kidney, etc.
PTHrP does not respond to negative feedback |
|
|
do PTH and PTHrP cross react in assays?
|
No, they react indepedently of one another
|
|
|
How does primary hyperparathyroidism differ from secondary?
|
Primary: usually caused by adenoma/hyperplasia
Secondary: caused by hypocalcemia caused by chronic renal disease, vitamin D deficiency, intestinal malabsorption, etc. |
|
|
CaI is decreased in secondary hyperparathyroidism (T/F)
|
True; secondary hypoparathyroidism is usually the result of chronic renal disease, which causes decreased Ca2+ reabsorption
|
|
|
How does acute pancreatitis affect calcium?
|
causes acute hypocalcemia
- increased fatty acids (due to inc. lipase) bind free calcium - malabsorption of calcium may cause increased PTH production |
|
|
How does hypomagnasemia affect calcium levels?
|
It causes hypocalcemia due to inhibition of PTH secretion and ineffective PTH binding to receptors in bone. |
|
|
Phytic acid
|
Plant chemical that binds dietary vitamin D and prevents its absorption
|
|
|
Removal of the parathyroid gland will cause ______, which produces what symptoms?
|
Primary hypoparathyroidism |
|
|
Treatment of primary hypoparathyroidism
|
High dosage Ca(2+) and vitamin D
|
|
|
Pseudohypoparathyroidism
|
PCT resistant to effects of PTH
- PTH is produced, but does not correct hypocalcemia - increased plasma phosphate - decreased plasma calcium and vitamin D - increased ALP |
|
|
Symptoms of pseudoparathyroidism |
renal osteodystrophy
|
|
|
Paget's disease
|
hyperactivity of osteoclasts, causing increased calcium, phosphate and ALP, while PTH is decreased due to negative feedback by calcium.
Phosphate remains elevated due to decreased PTH |
|
|
How do lab results of osteoporosis differ from the -parathyroidisms?
|
Osteoporosis will have no abnormal Ca/phsophate/ALP/PTH/VitD results
|
|
|
This molecule is increased in urine with osteoporosis
|
Pyridnoline
|
|
|
Sample requirements for calcium measurement
|
Whole blood/serum/plasma that:
- has not been exposed to air - has heparin anticoagulant - Iced down - <1 hr old |
|
|
The ionophore in calcium ISE
|
octyl-phenyl-phosphonate
|
|
|
What is another name for the dye-binding method of calcium measurement
|
Arsenzo method
|
|
|
How can the Arsenzo method for calcium measurement be modified to account for magnesium
|
By adding 8-hydroxyquinoline, which will complex free Mg2+
|
|
|
What pH level should be maintained for the Arsenzo method?
|
alkaline (pH<10) - 8-hydroxyquinoline will bind calcium instead of magnesium at more acidic pH |
|
|
Reference range for total calcium |
8.6-10 (-10.6 in children) mg/dL
|
|
|
Which other lab result should be looked at when looking at calcium levels
|
Albumin (decreased albumin means decreased total calcium) |
|
|
Severe hypophosphatemia is common in this group of disorders |
Acid-base disorders (ie. resp. alkalosis, DKA)
|
|
|
Hyperphosphatemia is associated with _____
|
renal insufficiency
|
|
|
Magnesium is predominantly (intracellular/extracellular)
|
Intracellular |
|
|
Hypermagnesemia can be caused by which conditions?
|
renal insufficiency |
|
|
The colloid in the thyroid gland has which physiologic function? |
Receiving and storing thyroglobulin produced by follicular epithelial cells |
|
|
The parafollicular cells of the thyroid produce and secrete: |
Calcitonin
|
