Calcium and bones Flashcards
(101 cards)
1
Q
What vitamin is required for calcium absorption?
A
Vitamin D
2
Q
What are the two sources of VD?
A
Diet and sunlight
3
Q
What can reduce dietary VD?
A
Lack of intake (elderly, certain diets, anorexia)
Phytate prevents VD absorption in gut
4
Q
What happens to VD?
A
Converted to 25(OH)-D by 25 hydroxylase in the liver
5
Q
What can block VD conversion in the liver?
A
Anticonvulsants
6
Q
Is 25(OH)-D active or inactive?
A
Inactive
7
Q
What happens to 25(OH)-D?
A
Converted to 1,25(OH)2-D in the kidneys
8
Q
Is 1,25(OH)2-D active or inactive?
A
Active
9
Q
What does 1,25(OH)2-D do to the gut?
A
Increases Ca and PO4 absorption
10
Q
What does 1,25(OH)2-D do to the kidneys?
A
Increases Ca reabsorption
11
Q
What can increase 1,25(OH)2-D synthesis?
A
PTH
Low PO4
12
Q
What can inhibit 1,25(OH)2-D synthesis?
A
High PO4
1,25(OH)2-D
13
Q
What stimulates PTH production?
A
Low Ca
14
Q
What inhibits PTH production?
A
1,25(OH)2-D
15
Q
What ion is required for PTH production?
A
Mg
16
Q
What does PTH do to the kidneys?
A
Stim 1,25(OH)2-D production
Increase PO4 excretion
Decrease Ca reabsorption
17
Q
What does PTH do to bones?
A
Increase Ca export
18
Q
What stimulates calcitonin production?
A
High Ca
19
Q
What effect does Ca have on bones?
A
Inhibits osteoclast breakdown of bone and Ca reabsorption
20
Q
What is an easy way to remember hypercalcemia?
A
Bones
Stones
Abdo groans
Psych moans
21
Q
What are some acute presentations of hypercalcemia?
A
Thirst
Dehydration
Confusion
Polyuria
22
Q
What are some chronic presentations of hypercalcemia?
A
Myopathy Fractures Osteopenia Depression Hypertension Pancreatitis
23
Q
How do you test for PTH?
A
Look for C peptide from it
24
Q
What are the two main causes of hypercalcemia?
A
Primary hyperparathyroidism
Malignancy
25
What drugs can cause hypercalcemia?
VD supplements
| Thiazide diuretics- decrease Ca excretion
26
What is the main hormone for regulation of Ca levels?
PTH
27
How can PTH deviate in hypercalcemia?
Can be high/normal or low/with high PO4
28
What does a low PTH or high PO4 suggest?
Bone pathology
29
What two categories of bone pathology are there?
High ALP and low ALP
30
What conditions can cause hypercalcemia with low ALP?
Myeloma
VD toxicity
Antacids
31
What conditions can cause hypercalcemia with high ALP?
Malignancy
Sarcoidosis
Thyrotoxicosis
32
How can malignancy cause hypercalcemia?
Metastatic bone destruction
PTHrp from solid tumours
Osteoclast activating factor release
33
How do you diagnose hypercalcemia producing malignancy?
Raised serum Ca and ALP
Imaging
Isotope bone scan
34
What two categories of hypercalcemia with high/normal PTH are there?
Increased Ur Ca excretion
| Decreased Ur Ca excretion
35
What can cause hypercalcemia with increased Ur Ca excretion?
Primary or tertiary hyperparathyroidism
36
What can cause hypercalcemia with decreased Ur Ca excretion?
Familial Hypocalciuric Hypercalcemia
37
How do you detect primary hyperparathyroidism?
High serum Ca and PTH
| High Ur Ca excretion
38
How do you treat primary hyperparathyroidism?
Surgery
| Cinacalcet- Ca mimetic
39
When is surgery indicated for primary hyperparathyroidism?
End organ damage occurring
<50YO
eGFR<60
Ca>2.85
40
What is secondary hyperparathyroidism?
Physiological response to low Ca or VD
41
How do you detect secondary hyperparathyroidism?
Low Ca
| High PTH
42
What is tertiary hyperparathyroidism?
Parathyroid becomes autonomous after prolonged secondary hyperparathyroidism.
43
How do you detect tertiary hyperparathyroidism?
High Ca and PTH
44
What is acute treatment of hypercalcemia?
Rehydrate w/ 0.9% saline 4-6L
Loop diuretics
Bisphosphonates
Steroids if caused by sarcoidosis
45
What are some genetic causes of hypercalcemia?
Familial isolated hyperparathyroidism
| MEN1/2
46
How do MEN1/2 cause hypercalcemia?
Development of parathyroid adenoma
47
How does familial isolated hyperparathyroidism cause hypercalcemia?
Adenoma which mimics primary hyperparathyroidism
48
What is FHH?
Mutation resulting in loss of Ca sensing R resulting in increased release of PTH
49
How does FHH present?
Mild hypercalcemia
Reduced Ur Ca excretion
PTH may be elevated
50
How else can you detect FHH?
Genetic screening
51
What are some signs and symptoms of hypocalcemia?
```
Paraesthesia in fingers and toes
Muscle cramps/tetany
Muscle weakness
Fatigue
Fits
Hyperexcitable nerve endings
```
52
When is acute hypocalcemia an emergency?
When it is symptomatic
53
How do you treat acute hypocalcemia?
IV calcium gluconate 10ml 10% over 10 mins in 50ml saline or dextrose
54
What can cause hypocalcemia?
Hypoparathyroidism
Hypomagnesemia
Pseudohypoparathyroidism
55
What can cause hypoparathyroidism?
```
DiGeorge syndrome
Destruction- surgery, radiotherapy, malignancy
Autoimmune
Hypomagnesaemia
Idiopathic
```
56
How do you manage hypocalcemia in the long term?
1-2g Ca a day
| VD tablets
57
What can cause hypomagnesaemia?
```
Alcohol
Drugs- thiazide/PPI
GI illness
Pancreatitis
Malabsorption
```
58
What is pseudohypoparathyroidism?
Genetic defect leading to PTH resistance
59
How does pseudohypoparathyroidism present?
```
Bone abnormalities
Obesity
Subcutaneous calcification
Learning disabilities
Brachdactyly- shortening of 4/5th metacarpals
```
60
What are two diseases of Ca and VD deficiency?
Rickets
| Osteomalacia
61
What can cause Rickets and osteomalacia?
```
Dietary insufficiency
Malabsorption
Chronic renal failure
Lack of sunlight
Drugs
```
62
How do you diagnose osteomalacia?
```
Low Ca
Muscle wasting- proximal myopathy
Dental defects
Bone tenderness (deep gnawing ache)
Fractures
```
63
At what age do we reach peak bone density?
~30YO
64
For how long do we remain at peak bone density?
10-15 years
65
What speeds up a woman's loss of bone density?
Menopause
66
What factors regulate peak bone mass?
```
Genetics
Body weight
Sex hormones
Diet
Exercise
```
67
What factors regulate bone loss?
```
Sex hormone deficiency
Body weight
Genetics
DIet
Immobility
Disease
Drugs- GS etc
```
68
What are some common fracture sites in osteoporosis?
Neck of femur
Vertebral body
DIstal radius
Humeral neck
69
How does osteoporosis of the vertebral body usually present?
Crush fractures/thoracic kyphosis
70
How do you assess bone density?
DEXA scans
71
Is osteoporosis painful?
Not until it breaks
72
What is a T score in DEXA scanning?
Current compared to peak mass for sex
73
What is a Z score in DEXA scanning?
Age matched (average for their age)
74
What are the three possible outcomes of a DEXA scan?
Normal
Osteopenia
Osteoporotic
75
What score is osteopenia on DEXA scanning?
1>score>2.5
76
What score is osteoporosis on DEXA scanning?
>2.5
77
When is only the Z score used?
If younger than 20
78
What are some endocrine causes of osteoporosis?
Hyperthyroidism
Hyperparathyroidism
Cushing's
79
What are some non-endocrine causes of osteoporosis?
```
GI diseases
CF
COPD
Chronic kidney disease
Age
```
80
What lifestyle interventions are good for osteoporosis?
HI strength training
Low impact weight bearing
Avoid alcohol and smoking
700mg+ of Ca a day
81
What are some drug treatments for osteoporosis?
Ca/VD supplements
Bisphosphonates
Testosterone
82
What are bisphosphonates?
Prevent reabsorption of Ca.
83
Give some examples of bisphosphonates
Alendronate
| Risedronate
84
What is Paget's disease?
Abnormal bone remodeling resulting in reduced strength
85
What causes Paget's disease?
Unclear. Poss: Viral, environmental or biochemical
86
Where does Paget's disease tend to affect?
Long bones
Pelvis
Lumbar spine
Skull
87
What are some signs of Paget's disease?
Bone pain and deformities
Deafness
Compression neuropathies
88
What is a rare complication of Paget's disease?
Osteosarcoma
89
How do you diagnose Paget's disease?
XR
Isotope bone scan
Raised ALP
90
How do you treat Paget's disease?
Analgesia
| Bisphosphonates
91
What is osteogenesis imperfecta?
Genetic disorder affecting bones. Due to lack of or abnormal collagen type I
92
What is a common sign of osteogenesis imperfecta?
China blue sclera
93
What are some signs of osteogenesis imperfecta?
```
China blue sclera
Bones that break with very little force
Dentinogenesis imperfecta (tooth problems)
```
94
How do you treat osteoporosis imperfecta?
No cure but fix fractures and surgery to correct
| Bisphosphonates
95
WHat are the two categories of bone abnormality?
Diffuse- all too brittle or soft
| Focal- Traumatic, neoplastic etc
96
In what disease are bones to brittle?
Osteoporosis
97
In what disease are bones to soft?
Rickets/osteomalacia and Paget's disease
98
Why can you get a high serum Ca with bone cancer and mets?
Increased Ca liberation as bones break down
99
What is a loss of bone due to neoplasia?
Lysis
100
What is a gain of bone due to neoplasia?
Sclerosis
101
What is a loss of bone due to non-neoplasia?
Lutic
