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Endocrine > Calcium and bones > Flashcards

Calcium and bones Flashcards

1
Q

What vitamin is required for calcium absorption?

A

Vitamin D

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2
Q

What are the two sources of VD?

A

Diet and sunlight

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3
Q

What can reduce dietary VD?

A

Lack of intake (elderly, certain diets, anorexia)

Phytate prevents VD absorption in gut

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4
Q

What happens to VD?

A

Converted to 25(OH)-D by 25 hydroxylase in the liver

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5
Q

What can block VD conversion in the liver?

A

Anticonvulsants

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6
Q

Is 25(OH)-D active or inactive?

A

Inactive

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7
Q

What happens to 25(OH)-D?

A

Converted to 1,25(OH)2-D in the kidneys

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8
Q

Is 1,25(OH)2-D active or inactive?

A

Active

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9
Q

What does 1,25(OH)2-D do to the gut?

A

Increases Ca and PO4 absorption

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10
Q

What does 1,25(OH)2-D do to the kidneys?

A

Increases Ca reabsorption

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11
Q

What can increase 1,25(OH)2-D synthesis?

A

PTH

Low PO4

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12
Q

What can inhibit 1,25(OH)2-D synthesis?

A

High PO4

1,25(OH)2-D

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13
Q

What stimulates PTH production?

A

Low Ca

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14
Q

What inhibits PTH production?

A

1,25(OH)2-D

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15
Q

What ion is required for PTH production?

A

Mg

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16
Q

What does PTH do to the kidneys?

A

Stim 1,25(OH)2-D production
Increase PO4 excretion
Decrease Ca reabsorption

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17
Q

What does PTH do to bones?

A

Increase Ca export

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18
Q

What stimulates calcitonin production?

A

High Ca

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19
Q

What effect does Ca have on bones?

A

Inhibits osteoclast breakdown of bone and Ca reabsorption

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20
Q

What is an easy way to remember hypercalcemia?

A

Bones
Stones
Abdo groans
Psych moans

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21
Q

What are some acute presentations of hypercalcemia?

A

Thirst
Dehydration
Confusion
Polyuria

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22
Q

What are some chronic presentations of hypercalcemia?

A 
Myopathy
Fractures
Osteopenia
Depression
Hypertension
Pancreatitis
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23
Q

How do you test for PTH?

A

Look for C peptide from it

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24
Q

What are the two main causes of hypercalcemia?

A

Primary hyperparathyroidism

Malignancy

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25
Q

What drugs can cause hypercalcemia?

A

VD supplements

Thiazide diuretics- decrease Ca excretion

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26
Q

What is the main hormone for regulation of Ca levels?

A

PTH

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27
Q

How can PTH deviate in hypercalcemia?

A

Can be high/normal or low/with high PO4

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28
Q

What does a low PTH or high PO4 suggest?

A

Bone pathology

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29
Q

What two categories of bone pathology are there?

A

High ALP and low ALP

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30
Q

What conditions can cause hypercalcemia with low ALP?

A

Myeloma
VD toxicity
Antacids

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31
Q

What conditions can cause hypercalcemia with high ALP?

A

Malignancy
Sarcoidosis
Thyrotoxicosis

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32
Q

How can malignancy cause hypercalcemia?

A

Metastatic bone destruction
PTHrp from solid tumours
Osteoclast activating factor release

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33
Q

How do you diagnose hypercalcemia producing malignancy?

A

Raised serum Ca and ALP
Imaging
Isotope bone scan

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34
Q

What two categories of hypercalcemia with high/normal PTH are there?

A

Increased Ur Ca excretion

Decreased Ur Ca excretion

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35
Q

What can cause hypercalcemia with increased Ur Ca excretion?

A

Primary or tertiary hyperparathyroidism

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36
Q

What can cause hypercalcemia with decreased Ur Ca excretion?

A

Familial Hypocalciuric Hypercalcemia

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37
Q

How do you detect primary hyperparathyroidism?

A

High serum Ca and PTH

High Ur Ca excretion

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38
Q

How do you treat primary hyperparathyroidism?

A

Surgery

Cinacalcet- Ca mimetic

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39
Q

When is surgery indicated for primary hyperparathyroidism?

A

End organ damage occurring
<50YO
eGFR<60
Ca>2.85

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40
Q

What is secondary hyperparathyroidism?

A

Physiological response to low Ca or VD

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41
Q

How do you detect secondary hyperparathyroidism?

A

Low Ca

High PTH

42
Q

What is tertiary hyperparathyroidism?

A

Parathyroid becomes autonomous after prolonged secondary hyperparathyroidism.

43
Q

How do you detect tertiary hyperparathyroidism?

A

High Ca and PTH

44
Q

What is acute treatment of hypercalcemia?

A

Rehydrate w/ 0.9% saline 4-6L
Loop diuretics
Bisphosphonates
Steroids if caused by sarcoidosis

45
Q

What are some genetic causes of hypercalcemia?

A

Familial isolated hyperparathyroidism

MEN1/2

46
Q

How do MEN1/2 cause hypercalcemia?

A

Development of parathyroid adenoma

47
Q

How does familial isolated hyperparathyroidism cause hypercalcemia?

A

Adenoma which mimics primary hyperparathyroidism

48
Q

What is FHH?

A

Mutation resulting in loss of Ca sensing R resulting in increased release of PTH

49
Q

How does FHH present?

A

Mild hypercalcemia
Reduced Ur Ca excretion
PTH may be elevated

50
Q

How else can you detect FHH?

A

Genetic screening

51
Q

What are some signs and symptoms of hypocalcemia?

A 
Paraesthesia in fingers and toes
Muscle cramps/tetany
Muscle weakness
Fatigue
Fits
Hyperexcitable nerve endings
52
Q

When is acute hypocalcemia an emergency?

A

When it is symptomatic

53
Q

How do you treat acute hypocalcemia?

A

IV calcium gluconate 10ml 10% over 10 mins in 50ml saline or dextrose

54
Q

What can cause hypocalcemia?

A

Hypoparathyroidism
Hypomagnesemia
Pseudohypoparathyroidism

55
Q

What can cause hypoparathyroidism?

A 
DiGeorge syndrome
Destruction- surgery, radiotherapy, malignancy
Autoimmune
Hypomagnesaemia
Idiopathic
56
Q

How do you manage hypocalcemia in the long term?

A

1-2g Ca a day

VD tablets

57
Q

What can cause hypomagnesaemia?

A 
Alcohol
Drugs- thiazide/PPI
GI illness
Pancreatitis
Malabsorption
58
Q

What is pseudohypoparathyroidism?

A

Genetic defect leading to PTH resistance

59
Q

How does pseudohypoparathyroidism present?

A 
Bone abnormalities
Obesity
Subcutaneous calcification
Learning disabilities
Brachdactyly- shortening of 4/5th metacarpals
60
Q

What are two diseases of Ca and VD deficiency?

A

Rickets

Osteomalacia

61
Q

What can cause Rickets and osteomalacia?

A 
Dietary insufficiency
Malabsorption
Chronic renal failure
Lack of sunlight
Drugs
62
Q

How do you diagnose osteomalacia?

A 
Low Ca
Muscle wasting- proximal myopathy
Dental defects
Bone tenderness (deep gnawing ache)
Fractures
63
Q

At what age do we reach peak bone density?

A

~30YO

64
Q

For how long do we remain at peak bone density?

A

10-15 years

65
Q

What speeds up a woman’s loss of bone density?

A

Menopause

66
Q

What factors regulate peak bone mass?

A 
Genetics
Body weight
Sex hormones
Diet
Exercise
67
Q

What factors regulate bone loss?

A 
Sex hormone deficiency
Body weight
Genetics
DIet
Immobility
Disease
Drugs- GS etc
68
Q

What are some common fracture sites in osteoporosis?

A

Neck of femur
Vertebral body
DIstal radius
Humeral neck

69
Q

How does osteoporosis of the vertebral body usually present?

A

Crush fractures/thoracic kyphosis

70
Q

How do you assess bone density?

A

DEXA scans

71
Q

Is osteoporosis painful?

A

Not until it breaks

72
Q

What is a T score in DEXA scanning?

A

Current compared to peak mass for sex

73
Q

What is a Z score in DEXA scanning?

A

Age matched (average for their age)

74
Q

What are the three possible outcomes of a DEXA scan?

A

Normal
Osteopenia
Osteoporotic

75
Q

What score is osteopenia on DEXA scanning?

A

1>score>2.5

76
Q

What score is osteoporosis on DEXA scanning?

A

> 2.5

77
Q

When is only the Z score used?

A

If younger than 20

78
Q

What are some endocrine causes of osteoporosis?

A

Hyperthyroidism
Hyperparathyroidism
Cushing’s

79
Q

What are some non-endocrine causes of osteoporosis?

A 
GI diseases
CF
COPD
Chronic kidney disease
Age
80
Q

What lifestyle interventions are good for osteoporosis?

A

HI strength training
Low impact weight bearing
Avoid alcohol and smoking
700mg+ of Ca a day

81
Q

What are some drug treatments for osteoporosis?

A

Ca/VD supplements
Bisphosphonates
Testosterone

82
Q

What are bisphosphonates?

A

Prevent reabsorption of Ca.

83
Q

Give some examples of bisphosphonates

A

Alendronate

Risedronate

84
Q

What is Paget’s disease?

A

Abnormal bone remodeling resulting in reduced strength

85
Q

What causes Paget’s disease?

A

Unclear. Poss: Viral, environmental or biochemical

86
Q

Where does Paget’s disease tend to affect?

A

Long bones
Pelvis
Lumbar spine
Skull

87
Q

What are some signs of Paget’s disease?

A

Bone pain and deformities
Deafness
Compression neuropathies

88
Q

What is a rare complication of Paget’s disease?

A

Osteosarcoma

89
Q

How do you diagnose Paget’s disease?

A

XR
Isotope bone scan
Raised ALP

90
Q

How do you treat Paget’s disease?

A

Analgesia

Bisphosphonates

91
Q

What is osteogenesis imperfecta?

A

Genetic disorder affecting bones. Due to lack of or abnormal collagen type I

92
Q

What is a common sign of osteogenesis imperfecta?

A

China blue sclera

93
Q

What are some signs of osteogenesis imperfecta?

A 
China blue sclera
Bones that break with very little force
Dentinogenesis imperfecta (tooth problems)
94
Q

How do you treat osteoporosis imperfecta?

A

No cure but fix fractures and surgery to correct

Bisphosphonates

95
Q

WHat are the two categories of bone abnormality?

A

Diffuse- all too brittle or soft

Focal- Traumatic, neoplastic etc

96
Q

In what disease are bones to brittle?

A

Osteoporosis

97
Q

In what disease are bones to soft?

A

Rickets/osteomalacia and Paget’s disease

98
Q

Why can you get a high serum Ca with bone cancer and mets?

A

Increased Ca liberation as bones break down

99
Q

What is a loss of bone due to neoplasia?

A

Lysis

100
Q

What is a gain of bone due to neoplasia?

A

Sclerosis

101
Q

What is a loss of bone due to non-neoplasia?

A

Lutic

Endocrine (23 decks)

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