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Bone Disorders Flashcards

1
Q

Regulation of calcium is by?

A

Vitamin d 25 and PTH

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2
Q

Leak of calcium by?

A

EcaC1 TRPV5 in kidney and EcaC2, TRPV6 in intestine

And pump basolateral calcium ATPase PMCA1b

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3
Q

EcaC expression is activated by?

A

1,25 VitD

Through gene transcription and phosphorylation of channels
And insertion of EcaC rich vesicles

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4
Q

Activation of vit D 1 alpha hydroxylation done by?

A

In kidney by PTH

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5
Q

As Phosphate increases, PTH

A

INCREASES

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6
Q

PTh half life

A

4 mins

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7
Q

Low magnesium causes?

A

Inhibits PTH release

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8
Q

Humeral hypercalcaemia malignancy caused by?

A

PTHrP

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9
Q

Enzymes for activation of cholecaciferol?

A

Renal 1 alpha hydroxylase and 25 hydroxylase

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10
Q

Calcitonin effect?

A

Reduce bone resorption

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11
Q

FGF23?

A

Reduced phosphate reabsorption in the renal proximal tubule and inhibits 1 alpha hydroxyase

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12
Q

Phosphate is secreted by?

A

Osteocytes, osteoblasts and osteoclasts

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13
Q

FGF23 can cause?

A

Reduction is phosphate reabsorption in renal proximal tubule, and inhibits 1 alpha hydroxylase

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14
Q

How much of calcium is ionised?

A

50%

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15
Q

What can total calcium be changed by?

A

Changes in albumin

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16
Q

Range for calcium is?

A

2.20 and 2.60 mmol/L

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17
Q

Hypercalcaemia with suppressed PTH is caused by?

A

Malignancy of blood, lung and breast, vit D excess and sarcoidosis

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18
Q

Hypercalcaemia with raised PTH caused by?

A

1 or 3 hyperparathyroidism or defects in calcium receptors FHH

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19
Q

Hypocalcaemia and increased PTH?

A

Vitamin D deficiency, malabsorption, renal failure, PTH receptor defect and vit D receptor defect

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20
Q

Hypocalcaemia and low or normal PTH?

A

Hypoparathyroidism, congenital Digeorge
Post surgery radiotherapy
Mg deficiency

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21
Q

What can cause Polyuria?

A

Diabetes insipidus and mellitus

Renal failure, high calcium and low potassium

22
Q

How does calcium cause polyuria?

A

Inhibits Gs preventing ADH on V2 receptor to absorb water via luminal AQP2 insertion

23
Q

Familial hypocalciuria hypercalcaemia is genetically?

A

Autosomal dominant, loss of function of calcium receptor

24
Q

To exclude FHH you would

A

Ca:cr ratio over 0.01

25
Q

MEN1 is for 3Ps?

A

Pituitary adenoma,
Parathyroid hyperplasia
Pancreatic tumours

Cause primary hyperparathyroidism is uncommon in younger people

26
Q

MEN2 is for 3cs?

A

Calcitonin:
Medullary thyroid carcinoma

Calcium:
Parathyroid hyperplasia

Catecholamines:
Pheochromocytoma

27
Q

Calcitonin is used to distinguish between?

A

C cell hyperplasia from medullary c cell carcinoma,

Pentagastrin stimulated values should be used

28
Q

Problems with CKD mineral bone disease 3 hyperparathyroidism?

A

Reduced glomerular filtration of phosphate and impaired renal tubular response leads to phosphate retention

Reduced renal mass causing less activity of 1a hydroxylase so failure to increase calcitrol

29
Q

Pseudohypoprathyroidism?

A

PTH resistance GNAS heterozygous mutation , G protein that couples the PTH receptor to adenylate cyclase

30
Q

Pseudohypoparathyroidism- Albright hereditary osteodystrophy phenotype?

A

Short stature, short 4/5 metacarpals and or metatarsals, round facies obesity and mild mental retardation

31
Q

Weird aspect of pseudohypoparathyroidism?

A

If mutant gene from mum then biochemical and physical features- genetic imprinting

If from father only physical features- PTH receptor not in kidney

32
Q

Genetic imprinting?

A

Only a maternal or paternal gene is imprinted and not both

33
Q

Pagets disease?

A

Dysregulated bone growth, immobilisation
Hypercalcaemia

High ALP

34
Q

Calcium alkali syndrome?

A

Triad of hypercalcaemia, metabolic alkalosis and AKI renal insufficiency due to ingestion of large amounts of calcium and absorbable alkali

35
Q

How do sarcoidosis cause hypercalcaemia?

A

Granulomas produce ACE, and a1 hydroxylase activates vit D

36
Q

EDTA contamination causes what?

A

Chelation of ions such as calcium, magnesium and zinc

ALP needs zinc as cofactor so low activity

37
Q

Difference between diabetes insipidus and mellitus?

A

In mellitus blood glucose levels are high

38
Q

ECaC2 can be found in?

39
Q

ECaC1 can be found in?

40
Q

What does active vitamin D do?

A

Gene transcription, phosphorylation of channels and insertion of ECaC rich vesicles

41
Q

Low magnesium does what?

A

Inhibits release of PTH

42
Q

What does PTHrP do?

A

Stimulated transport of calcium across placenta

Contributes to the bone loss during lactation

43
Q

What is calcitonin a marker for?

A

Tumour marker for medullary carcinoma of thyroid

44
Q

Adjusted calcium equation?

A

Calcium + 0.02* (40-albumin)

45
Q

Normocalcaemia hyperparathyroidism causes?

A

Primary hyperparathyroidism, vit D deficiency, CKD, acute illness, malabsorption dietary and drugs

46
Q

High ALP can be suggestive of?

A

Hyperparathyroidism

47
Q

FHH equation

A

Urine calcium x plasma creatnine/1000
Over
Calcium plasma x urine creatnine

48
Q

Sarcoid is?

A

Inflamed cells clump otgether to make small lumps called granulomas

49
Q

PTH responds to?

A

fall in plasma ionised calcium (acute)

- rise in plasma phosphate (chronic)

50
Q

What is the main tumour marker for medullary carcinoma of the thyroid?

A

Calcitonin

51
Q

Normocalcaemic hyperparathyroidism causes?

A 
Primary hyperparathyroidism
Vit d deficiency 
CKD- low 1,25 D, high PTH due to hyper phosphataemia
Acute illness
Malabsorption 
Drugs
52
Q

What is the Ca:Cr ratio?

A

Urine calcium x plasma creatinine

/

Plasma calcium x urine creatnine

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