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Junior - endo II > 12 - Calcium Metabolism > Flashcards

12 - Calcium Metabolism Flashcards

1
Q

5 w’s of calcium

A 
Who: people
What: Calcium
Where: 99%: in bones 1: circulating
When: always 
Why: Essential body mineral
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2
Q

What is the breakdown of the the 1% free calcium’?

A

50% is free (ionized) (physiologically active)
40% is bound to protein (albumin, globulin)
10% is bound to bicarb, citrate, phosphate

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3
Q

How much does calcium fluctuate?

A

It fluctuates constantly, changes hour to hour

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4
Q

What are the primary regulators of serum calcium?

A

PTH
Vitamin D
Calcitonin

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5
Q

What regulates PTH?

A

PTH secretion is

stimulated by: free falling (ionized) calcium levels

suppressed by: rising free (ionized) calcium levels

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6
Q

What actions does PTH do?

A
  • Stimulates resorption (or dissolution) of bone by osteoclasts
  • increases renal tubular resorption of calcium
  • stimulates intestinal activation of vitamin D
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7
Q

Why would PTH stimulate resorption ob bone by osteoclasts?

A

It increases delivery of calcium and phosphorus to the circulation

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8
Q

What effect does vitamin D have on the process?

A

it enhances intestinal absorption of calcium and phosphate from intestines

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9
Q

What is calciferol?

A

Vitamin D

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10
Q

How is vitamin D converted?

A

7-DHC (cholesterol) is exposed to light (UVB range)

Then it is transformed in the liver

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11
Q

Active form of vitamin D?

A

1,25(OH)2D

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12
Q

Where is calcitonin made?

A

Produced by the parafollicular cells of the thyroid gland in response to an elevated serum calcium

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13
Q

What does calcitonin do?

A

Minor role in plasma calcium concentration

Inhibits calcium resorption from bone (inhibits osteoclasts)

Increases calcium in bones

Increase renal excretion of calcium

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14
Q

When does calcitonin get released?

A

After calcium is removed from bones it is released to bring bone levels back up

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15
Q

What are the failures of calcium homeostasis we are concerned about?

A

Hypercalcemia

Hypocalcemia

Failure to maintain normal bone

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16
Q

What needs to be checked to determine the cause of hypercalcemia?

A

Check the PTH

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17
Q

MC cause of increased PTH?

A

Primary hyperparathyroidism

80% parathyroid adenoma
20% parathyroid hyperplasia
<1% parathyroid cancer

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18
Q

Hypercalcemia with normal PTH

A

Its familial hypocalciuric hypercalcemia (FHH)

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19
Q

Hypercalcemia with suppressed PTH?

A

Secondary malignancy

Vitamin D excess

High bone turnover (thyrotoxicosis)

Immobilization

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20
Q

Ss of hypercalcemia (of any cause)

A

Often asymptomatic
But classic signs are:

Stone: kidney stones
bones: bone pain/fracture
Groans: anorexia, dyspepsia, constipation
moans: myalgia, weakness, joint pain
overtones: depression, memory loss lethargy

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21
Q

If severe hypercalcemia (Ca >14mg/dL)?

A

Malignancy

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22
Q

Do symptoms correlate with acuity and severity of calcium level increase?

A

Nope

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23
Q

Parathyroid adenoma s/s?

A

Usually mild or asymptomatic

20% get kidney stones

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24
Q

Labs for parathyroid adenoma?

A

Serium Ca 2+ = > 10.5mg/dL
24 hr urine ca and po increased
PTH = elevated serum levels

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25
Q

Imaging for parathyroid adenoma?

A

Not necessary for diagnosis

But conducted pre surgery
US, CT, MRI

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26
Q

Tx for parathyroid adenoma?

A

Symptomatic:
no definitive medical tx but
- Good hydration
- Parathyroidectomy

Asymptomatic:
- watch it, wait for symptoms

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27
Q

When should parathyrodectomy be considered?

A
  • Serium ca is super high
  • hx of life-threatening hypercalcemia
  • kidney stones on x ray
  • 30% reduced creatine clearance
  • 24hr urine calcium > 400
  • evidence of severe osteoporosis
  • pt < 50yrs
  • pregnancy (2nd trimester)
  • med: pt compliance issues
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28
Q

Common complications with parathyroid adenoma?

A

Pathologic fx

UTIs from stones/obstruction -> renal failure and uremia

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29
Q

If pt has parathyroid hyperplasia what condition is often associated with it?

A

MEN 1, 2, 3 and 4

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30
Q

Presentation and tx of parathyroid hyperplasia?

A

Same as parathyroid adenoma

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31
Q

What is familial hypocalciuric hypercalcemia?

A

Autosomal dominant disorder that is benign

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32
Q

S/s of Famila hypocalciuric hypercalcemia>

A

Lifelong hypercalcemia and hypocalcinuria

Usually asymptomatic

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33
Q

Should we do surgery for familial hypocalciuric hypercalcemia?

A

If you remove the PT glands you also stop the PTH

This leads to hypocalcemia…

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34
Q

10-20% of cancer pts will have?

A

Hypercalcemia

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35
Q

What is PTHrP?

A

PTH related protein

Released by cancer and causes bone resorption and hypercalcemia similar to PTH

36
Q

What cancers usually release PTHrP?

A 
Squamous cell cancer
Renal 
Bladder
Ovarian
Breast 
Lukemia
Lymphoma
37
Q

What ways other than PTHrH can cause hypercalcemia with suppressed PTH?

A

Localized bone destruction from breast cancer

Tumors releasing calcitrol/vit D

38
Q

What do hodgkins disease and non-hodgkins lymphoma often release?

A

Tumors that produce calcitriol and vitamin D

39
Q

Sources of excess vitamin D?

A

Exogenous vitamin D

Endogenous production from: 
Lymphoma
Granulomatous disease (TP, sarciodosis etc)
40
Q

What causes a high rate of bone turnover?

A

Hyperthyroidism

41
Q

What effect does immobilization have on calcium levels?

A

Marked resorption of calcium from bone

42
Q

How to manage hypercalcemia?

A 
Hydrate
Stay active
Furosemide (calciuresis)
Avoid thiazide diuretics  
Avoid vitamins A and D and calcium
Dialysis for renal failure pts
Parathyroidectomy (severe cases)
43
Q

What effects do biphosphates have?

A

They inhibit bone resorption of calcium by osteoclasts

44
Q

When are bisphosphates used?

A

Hyperparathyroidism
Malignancy
Prolonged immobilization

45
Q

How to manage hypercalcemia pts?

A 
Check: 
calcium and albumin q 6 mo
Renal function q 12 mo
Bone mineral density q 1-2 yrs
Estrogen therapy (menopause)
46
Q

MC cause of hypocalcemia?

A

CKD - decreased productio of vitamin D and hyperphosphatemia are implicated

47
Q

If an elderly pt is hospitalized w hypocalcemia and hypophosphatemia you should check?

A

Vitamin D

48
Q

Etiologies of hypocalcemia?

A

PTH resistance
Vitamin D deficiency
Vitamin D resistance
PTH deficiency

49
Q

If albumin is low what needs to be cecked?

A

Obtain a corrected Ca level

Serum calcium + 0.8 (4-serum albumin)

50
Q

S/S of hypocalcemia?

A 
Paresthesias
Muscle cramps
Tingling hands, feet, circumoral area
Irritability,
Confusion
Seizures
Tetany 
Laryngospasms
Bronchospasms
Prolonged QT
Coma 
Chvostek’s sign
Trousseau’s sign
51
Q

Chvostek’s sign

A

Tapping on facial nerve causes facial spasm

52
Q

Trousseau’s sign?

A

Carpal spasm occurs when BP cuff is inflated above systolic pressure for up to 3 min

53
Q

Mnemonic for hypocalcemia S/S?

A

CATS go numb

C - convulsions
A - arrhythmias
T - tetany
S - seizures
Numbness/parasthesias in hands feet, mouth and lips
54
Q

Tx for sever hypocalcemia?

A

Intravenous calcium gluconate

55
Q

Labs for hypocalcemia?

A 
Total calcium
Free clcdum 
Albumin level
Corrected total calcium
Magnesium level
Check PTH 
Vitamin D
56
Q

Hypocalcemia with an elevated PTH?

A

PTH resistance or pseudohypoparathyrodism

Or

Low vitamin D

57
Q

PTH resistance effects?

A

Albrights hereditary oteodysrophy

Pts have short stature, rounded facies and short 4th and 5th metacarpals

58
Q

Causes of vitamin D deficiency?

A

Defective supply: dietary intake
Malabsorption: sprue, crohns
Defective processing: liver, kidney, meds

59
Q

Vitamin d deficiency in kids?

A

Rickets: poor bone growth and mineralization

60
Q

Vitamin D deficiency in adults?

A

Osteomalacia

- abnormal bone mineralization -> bone pain

61
Q

X rays of osteomalacia?

A

Long bones have thin, radiolucent lines (loosers lines)

62
Q

Vitamin D resistance?

A

Vitamin D is elevated but they still have rickets or osteomalacia because of a genetic defect

63
Q

Hypocalcemia with low PTH?

A

PTH deficiency

  • surgical damage
  • hypomagnesemia
  • autoimmune
  • congenital absence of parathyroid glands
64
Q

Hypocalcemia tx in asymptomatic pts?

A

Oral calcium supplements
Oral vitamin D supplements
Increased sunlight

Goal is to Keep serum ca level low-normal

65
Q

What is hypoparathyroid tetany?

A

Acute hypocalcemia

66
Q

Is hypoparathyoid tetany a big deal?

A

Yeah its a medical emergency

67
Q

What symptoms are commonly seen with hypoparathyroid tetany?

A

Decreased level of circulating PTH -> decreased serum Ca

Tetany and other hypocalcemia symptoms are common

68
Q

Treatment for acute hypocalcemia?

Inpatient

A

Airway mgmnt
MgSO4IV
Calcium gulconate IV
Transplant of cryopreserved parathyroid tissue
Oral calcium and vit D (once they are stabalized)

69
Q

What is tetany?

A

Intermittent muscular spasms caused by malfunction of the parathyroid glands and a consequent deficiency of calcium

70
Q

Treatment for acute hypoparathyroid tetany?

Outpatient care

A

Maintain ca at low normal
Calcium and vitamin D suppliments
Monotor ca q 3 mo (hypercalcemia)
Use HCTZ + K supp prn for Hypercalcinuria

71
Q

How is calcium monitored in outpatient care?

A

“Spot” urine calcium assay to check for hypercalcinuria

72
Q

What is pagets disease of bone?

A

Unknown cause

Excess bone lysis followed by replacement with vascular fibrous connective tissue leading to disorganized osteoid formation

Lytic lesions

73
Q

Prevalence of pagets disease?

A

Common in europe

US:
2-3% of adults over 55
10% over 80yrs

74
Q

S/S of pagets disease?

A

Asymptomatic
Bone pain (1st symptom)
Bone deformities
Warmth over bones

75
Q

Bone pain in pagets disease

A

Constant pain that is worse at night

not precipitated by wt bearing or exercise
not relieved by rest

Seen in one or several bones

76
Q

Bone deformities seen in pagets?

A

Bowed tibias
Kyphosis
“Chalk stick” fx w slight trauma

77
Q

labs for pagets disease?

A

Elevated:
Serum alkaline phosphate

Normal:
Serum calcium,
phosphorous
PTH

Urinary hydroxyproline elevated (bone resorption marker)

78
Q

Imaging with pagets disease?

A

Lytic lesions and multple fissure fx of long bones

Increased bone density and expansion

79
Q

What does a bone scan show for pagets disease?

A

Diffuse uptake in
Skull
Pelvis
Long bones

80
Q

Pagets bones look strong, are they?

A

No they just look dense on x ray

81
Q

Complications seen with pagets disease?

A 
High output cardiac failure
Osteoarthritis 
Hypercalcemia
Osteosarcoma (uncommon)
Fx w min trauma
Spinal cord compression from vertebral fx
Deafness
82
Q

Why does pagets disease cause deafness?

A

Excess bone in the auditory region

83
Q

Tx for pagets disease?

A

Asymptomatic:
- monitor levels and xrays

Symptomatic:
Treat complications

84
Q

DOC for pagets for bone resorption?

A

Biphosphates given cyclically

85
Q

Nasal calcitonin-salmon?

A

Less often used tx for pagets disease

86
Q

How do pigs talk?

A

Swine language

Junior - endo II (7 decks)

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