Bone physiology & disorders Flashcards Preview

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Flashcards in Bone physiology & disorders Deck (44):
1

What is involved in calcium homeostasis?

Diet
Gut absorption
Vitamin D
Parathyroid hormone

2

What changes to gut absorption can affect calcium homeostasis?

Bowel pathology
Age
Hormones (pregnancy & lactation)

3

What changes to parathyroid hormone can affect calcium homeostasis?

Hyperparathyroidism
Hypoparathyroidism
Malignant hypercalcaemia (parathyroid hormone related protein)

4

What changes to vitamin D can affect calcium metabolism?

Diet
Kidney problems
Liver problems
UVB exposure
Drugs

5

Describe calcium homeostasis

When calcium binds to the calcium sensing receptors on the parathyroid glands it suppresses the secretion of parathyroid hormone

Low calcium >
Parathyroid hormone is secreted >
Parathyroid hormone acts on the bones and kidneys >
Parathyroid hormone stimulates bone reabsorption, calcium reabsorption in the kidney and absorption in the small intestine via vit D synthesis in the kidney

6

What effect does low vitamin D have on parathyroid hormone levels?

It causes them to increase

7

Describe vitamin D metabolism

Dehydrocholesterol > sunlight
Cholecalciferol (D3) > liver
25 OH vit D > kidneys
1,25 OH vit D > effects on gut and kidney absorption of calcium and increase in bone density

8

What are the acute and chronic symptoms of hypercalcaemia?

Acute - thirst, dehydration, confusion, polyuria
Chronic - myopathy, osteopenia, fractures, depression, hypertension, abdominal pain, constipation

9

In hypercalcaemia what are the possible causes of abdominal pain?

Pancreatitis
Ulcers
Renal stones

10

What is the phrase used to remember symptoms of hypercalcaemia?

Stones, groans, bones and psychic moans

11

Which investigations are indicated in syspected hypercalcaemia?

Calcium
Albumin
Parathyroid hormone
Phosphate
Urine calcium

12

What would raised albumin and urea indicate?

Dehydration

13

What would raised albumin and normal urea indicate?

Cuffed blood sample

14

What would normal/low albumin, low PTH and high phosphate indicated?

Bone pathology

15

What would normal/low albumin, high PTH, low/normal phosphate and high urine calcium indicate?

Primary/tertiary hyperparathyroidism

16

What would normal/low albumin, high PTH, low/normal phosphate and low urine calcium indicate?

Familial hypocalciuric hypercalcaemia

17

Which test can you use to further assess bone pathology?

Alkaline phosphate

18

What does high alkaline phosphate in the context of the other investigations indicate?

Bone metastases
Sarcoidosis
Thyrotoxicosis

19

What does low alkaline phosphate in the context of the other investigations indicate?

Myeloma
Vitamin D excess
Mild alkaline syndrome (thyrotoxicosis, sarcoidosis & raised bicarbonate)

20

List some causes of hypercalcaemia?

Primary hyperparathyroidism
Malignancy
Familial hypocalciuric hypercalcaemia
Vitamin D
Thiazide diuretics
Granulomatous disease (sarcoid, TB)
Turnover (bedridden, thyrotoxic, Paget's)
Tertiary hyperparathyroidism/end stage renal disease

21

What investigations are indicated in primary hyperparathyroidism and what do they show?

Serum calcium (raised)
Serum PTH (raised/normal)
Urine calcium (raised)

22

How can malignancy cause hypercalcaemia?

Metastases
PTH related peptide (paraneoplastic)
Osteoclast activating factors

23

How can hypercalcaemia from malignancy be investigated?

Calcium (raised)
Alkaline phosphate (raised)
Imaging (x-ray, CT, MRI)
Isotope bone scan

24

How is acute hypercalcaemia treated?

Fluids (0.9% saline 4-6L)
Loop diuretics once rehydrated
Biphosphonates
Steroids (occasionally for inflammation)
Chemotherapy (malignant disease)

25

Can thiazide diuretics be used in hypercalcaemia?

No

26

What imaging scan can be used to detect parathyroid pathology?

Sestamibi scan

27

How is primary hyperparathyroidism treated?

Surgery (not always required)

28

Which parathyroid pathologies can cincalcet be used treat?

Tertiary hyperparathyroidism
Parathyroid carcinoma

29

What are the indications for parathyroidectomy?

End organ damage (bone disease, gastric ulcer, renal stones, osteoporosis)
High calcium (>2.85)
Under 50
eGFR

30

What is primary hyperparathyroidism? How does it present in terms of biochemistry?

Primary overactivity of parathyroid (e.g adenoma)
Calcium high & PTH high

31

What is secondary hyperparathyroidism? How does it present in terms of biochemistry?

Physiological response to low calcium
Calcium low & PTH high

32

What is tertiary hyperparathyroidism? How does it present in terms of biochemistry?

Parathyroid becomes automous after many years of secondary hyperparathyroidism
Calcium high & PTH high

33

What genetic syndromes is parathyroid associated with?

Multiple endocrine neoplasia type 1 & 2
Familial hyperparathyroidism

34

What is the biochemical picture with malignant hypercalcaemia?

Raised calcium
Normal phosphate
Raised alk phosphate

35

What investigations are useful in suspected malignant hypercalcaemia?

X-ray
Bone scan

36

How is myeloma screened for?

Protein electrophoresis
Benz jones
Skeletal survey

37

Is familial hypocalciuric hypercalcaemia autosomal dominant or recessive?

Dominant

38

How does familial hypocalciuric hypercalcaemia present?

Usually assymptomatic

39

How is familial hypocalcuric hypercalcaemia investigated?

Mildly elevated blood calcium
Reduced urine calcium
PTH mildly elevated
Genetic screening

40

What is the typical biochemistry of Paget's?

Calcium, parathyroid hormone and phosphate normal
Alk phosphate raised

41

What is the typical biochemistry of osteomalacia?

Calcium and phosphate low
Parathyroid hormone and alk phosphate raised

42

What is the typical biochemistry of hypoparathyroidism?

Calcium and parathyroid hormone low
Alk phosphate and phosphate normal

43

What is the typical biochemistry of malignant hypercalcaemia?

Calcium and alk phosphate raised
Parathyroid hormone low
Phosphate normal

44

What is the typical biochemistry of primary hyperparathyroidism?

Calcium and parathyroid hormone raised
Alk phosphate normal
Phosphate low

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