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Clinical Pathology > Calcium > Flashcards

Calcium Flashcards

1
Q

__% of the body’s calcium is in bone

A

99%

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2
Q

The remaining calcium in the body that is NOT in bone (1%) is in the blood. Out of that 1%, about __% is ionized (free), about __% is bound to plasma proteins (albumin), and the remaining __% is bound to anions (phosphate, bicarbonate)

A

50%, 40%, 10%

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3
Q

___ is the most abundant mineral in the body

A

Calcium

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4
Q

Because calcium is relatively insoluble it is poorly absorbed from the intestinal tract unless you have Vitamin __

A

D

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5
Q

__/6’s of calcium is excreted via the feces while the remaining __/6 is through the urine

A

5/6’s, 1/6th

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6
Q

What are the two hormones involved in INCREASING plasma calcium?

A
  1. Parathyroid hormone (PTH)

2. 1,25 dihydroxycholecalciferol (1,25 DHCC)

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7
Q

What is the plasma calcium LOWERING hormone?

A

Calcitonin

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8
Q

Removal of half (2) of the parathyroid glands causes no abnormality, but removing 3/4ths causes transient ______

A

Hypoparathyroidism

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9
Q

Name the hormone:

  1. Releases calcium from bone
  2. Lowers the serum phosphorus levels
  3. Reduces the renal clearance of calcium
  4. Promotes the production of 1-25 DHCC in the kidney
A

Parathyroid hormone (PTH)

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10
Q

A component of 1-25 DHCC normally present in the diet

A

Cholecalciferol (D3)

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11
Q

D3 (cholecalciferol) has to undergo hydroxylation ___ before reaching full physiological activity

A

Twice

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12
Q

The first step of D3 hydroxylation (25-hydroxylation) takes place in the ____, while the second step (1-hydroxylation) takes place in the ____

A

Liver, kidney

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13
Q

Name the hormone:

  1. Important in the absorption of calcium from the intestine
  2. Also in deposition and resorption of calcium salts in bone
  3. May also have direct PTH-like effects on the renal tubule
A

1-25 DHCC

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14
Q

Another name for 1-25 DHCC?

A

Calcitriol

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15
Q

This hormone increases the activity of the activating enzyme AMP in the proximal tubules of the kidney, which increases conversion of calcidiol (25HCC) to calcitriol (1,25 DHCC)

A

PTH

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16
Q

___ causes increased renal reabsorption of calcium, increased GI tract absorption of calcium, and the drawing out of some calcium from bone

A

Calcitriol (1,25 DHCC)

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17
Q

___ inhibits renal tubule phosphate reabsorption, which results in loss of phosphorus into the urine

A

Calcitriol (1,25 DHCC)

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18
Q

When the serum calcium level is elevated on at least ___ separate determinations the patient is said to have hypercalcemia

A

3

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19
Q

____ calcium is the physiologically active form of calcium

A

Ionized (free)

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20
Q

The most common cause of hypercalcemia is _____

A

Hyperparathyroidism

21
Q

The second most common cause of hypercalcemia

A

Malignancy

22
Q

The two ways that a malignancy can cause hypercalcemia?

A
  1. Metastasis to bone causes bone destruction, increased serum calcium
  2. The cancer can produce PTH-like substance (ectopic PTH) that increases calcium levels
23
Q

___ infections, such as sarcoidosis or TB are associated w/hypercalcemia

A

Granulomatous

24
Q

___ occurs in patients w/hypoalbuminemia. MCC is malnutrition (especially alcoholics)

A

Hypocalcemia

25
Q

Serum calcium is normally kept within narrow limits. What are they?

A

8.5-10.5 mg/dL

26
Q

The correction of serum calcium for depressed albumin: Adjusted Calcium = ______

A

Serum calcium - serum albumin +4.0

27
Q

If H+ falls (increased pH, alkalosis), calcium binds more to albumin and ionized calcium levels ____. The opposite is true if H+ rises (decreased pH, acidosis).

A

Fall

28
Q

pH is inversely related to calcium (meaning if pH rises the (ionized) calcium falls)

A

True

29
Q

Possible critical values for serum calcium:

A

<6.6 mg/dL (may lead to tetany)

>12.9 mg/dL (may lead to coma)

30
Q

___mg of calcium is bound to 1.0g of albumin

A

0.8

31
Q

If serum albumin is low, to correct, add 0.8mg/dL for every 1.0g/dL that serum albumin falls below ___g/dL

A

4.0

32
Q

Multiple myeloma would cause ____albuminemia and in turn ____calcemia

A

Hyper, hyper

33
Q

Dehydration causes ___ serum calcium levels

A

Increased

34
Q

Venous stasis during blood collection by prolonged application of tourniquet would cause ___ serum calcium levels

A

Increased

35
Q

If a patient has hypercalcemia, measure ___ next and ask about Vitamin D intake

A

PTH

36
Q

Secondary hyperparathyroidism (renal rickets, renal osteomalacia) actually causes _____ before the normal hyperparathyroidism effects take place

A

Hypocalcemia

37
Q

It seems in general that osteomalacia causes ___calcemia

A

Hyper

38
Q

The most common malignant tumor causing hypercalcemia?

A

Breast

39
Q

The most common cause of hypercalcemia in hospitalized patients

A

Malignant tumors (breast, lung, kidney)

40
Q

The only common primary bone tumor to produce hypercalcemia

A

Multiple myeloma

41
Q

__% of patients w/Hodgkin or non-Hodgkin Lymphoma would cause hypercalcemia due to ectopic production of 1,25 dihydroxy-vitamin D3

A

2%

42
Q

By far, what are the three most common causes of hypercalcemia?

A
  1. Primary hyperparathyroidism
  2. Malignant tumors
  3. Drugs (i.e. Vitamin D/A intoxication, Diuretics, estrogens, thyroid hormone, etc.)
43
Q

List the 3 possibilities that cause primary hyperparathyroidism:

A
  1. Adenoma
  2. Carcinoma
  3. Hyperplasia
44
Q

Chronic renal failure is considered ____ hyperparathyroidism

A

Tertiary

45
Q

Secondary hyperparathyroidism is caused by ___ deficiency

A

Vitamin D

46
Q

Most common cause of borderline or slightly elevated hypercalcemia?

A

Artifact (lab error, excess venous stasis, serum protein elevation)

47
Q

What are the two mnemonics for remembering hypercalcemia?

A
  1. CHIMPS

2. VITAMINS TRAP

48
Q

CHIMPS stands for?

A 
Cancer
Hyperthyroid
Iatrogenic
Multiple Myeloma
Primary hyperparathyroidism
Sarcoidosis (Granulomatous disease)

Clinical Pathology (12 decks)

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