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Endocrinology > Calcium metabolism and Disorders > Flashcards

Calcium metabolism and Disorders Flashcards

1
Q

where do you get vitamin D from

A

skin and diet

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2
Q

where is vitamin D converted

A

the liver

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3
Q

what does PTH do to vit D and calcium

A

stimulates the phosphorylation of vit D and reduces calcium (in bone, increases it in serum)

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4
Q

what is the main stimulus of PTH

A

low serum calcium

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5
Q

what senses serum calcium

A

calcium sensing receptor (C ASR) (GPCR)

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6
Q

describe how the mineralised aspects of bone are formed

A

inorganic pyrophosphate turns into inorganic phosphate- by alkaline phosphatase- which joins to calcium to make hydroxyapatite

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7
Q

what promotes bone mineralisation

A

PTH (elevated serum calcium promotes bone mineralisation) and sclerostin

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8
Q

what can make you loose the ability to metabolise vit D

A

renal failure, nephrectomy, hypoparathyroidism, anticonvulsants

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9
Q

what are the general symptoms of hypercalcaemia

A

Bones (ache)
Stones (kidney stones)
Abdominal Groans
Psychic Moans

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10
Q

what are the acute symptoms of hypercalcaemia

A

Thirst
Dehydration
Confusion
Polyuria

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11
Q

what are the chronic effects and symptoms of hypercalcaemia

A 
Myopathy
Fractures
Osteopaenia
Depression
Hypertension
Pancreatitis
Duodenal ulcer
Renal calculi
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12
Q

how do you investigate hypercalcaemia

A

PTH

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13
Q

what can cause hypercalcaemia with a low PTH

A

bone pathology

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14
Q

what do you check in hypercalcaemia with a low PTH

A

ALP

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15
Q

what can cause hypercalcaemia with a low PTH and a high ALP

A

Metastases
Sarcoidosis
Thyrotoxicosis

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16
Q

what can cause hypercalcaemia with a low PTH and a low ALP

A

Myeloma
Vit D Toxicity
Milk-Alkali (take too many rennie make gut alkaline
Thyrotoxicosis, sarcoid, HCO3

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17
Q

what do you check in hypercalcaemia with high/normal PTH

A

urine calcium excretion

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18
Q

what can cause hypercalcaemia with a high/normal PTH and a low urine calcium excretion

A

FHH- Familial Hypercalcemic Hypocalciuria

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19
Q

what can cause hypercalcaemia with a high/normal PTH and a high urine calcium excretion

A

primary/ tertiary hyperparathyroidism

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20
Q

what drugs can cause hypercalcaemia

A

Vit D, thiazides

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21
Q

what are the most common causes of hypercalcaemia

A

Primary Hyperparathyroidism

Malignancy

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22
Q

what diseases can cause hypercalcaemia

A

Primary Hyperparathyroidism
Malignancy
Granulomatous Disease eg Sarcoid, TB
Familial Hypocalciuric Hypercalcaemia
High turnover: bedridden, thyrotoxic, Pagets
Tertiary hyperparathyroidism (usually renal disease)

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23
Q

how do thiazides cause hypercalcaemia

A

reduce ability to secrete calcium

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24
Q

how do you diagnose primary hyperparathyroidism

A

Raised serum calcium
Raised serum PTH (or inappropriately normal)
Increased urine calcium excretion
Ensure Vitamin D replete

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25
Q

how does malignancy cause hypercalcaemia

A

Metastatic Bone destruction
PTHrp (PTH related peptide) from solid tumours
Osteoclast activating factors

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26
Q

how do you diagnose hypercalcaemia due to malignancy

A

Raised calcium and alkaline phosphatase (and a low PTH)
X-ray, CT, MRI
Isotope Bone Scan

27
Q

what is the acute treatment for hypercalcaemia

A

fluids- saline
Consider loop diuretics once rehydrated- avoid thiazides
Bisphosphonates- single dose will lower Ca over 2-3d, maximum effect at 1 week
Steroids occasionally used e.g Pred 40-60mg/day for sarcoidosis

28
Q

what can reduce calcium in metastatic disease

A

chemotherapy

29
Q

what is the management for primary hyperparathyroidism

A

surgery
Cinacalcet- Cacium Mimetic (mimic calcium on PTH receptor, reduced PTH secretion)
Can be useful if need treatment, but unfit for surgery

30
Q

what are the indications for a parathyroidectomy

A 
End Organ Damage:
Bone disease (Osteitis Fibosa et cystica; brown tumours/  pepper pot skull)
Gastric ulcers
Renal stones
Osteoporosis

very high calcium (>2.85)
under age 50
eGFR<60

31
Q

why is the treatment for osteoporosis PTH when hyperparathyroid causes osteoporosis

A

PTH in non continuous injection (non pulsuatile as normal) will get rid of receptors and have paradoxical effect to normal affect of PTH on bone

32
Q

what is secondary hyperparathyroidism

A

Physiological response to low calcium or vit D

33
Q

what is tertiary hyperparathyroidism

A

Parathyroid becomes autonomous after many years of overactivity e.g renal failure

34
Q

what is primary hyperparathyroidism

A

Primary overactivity of Parathyroid gland i.e adenoma or carcinoma

35
Q

what genetic syndromes are linked to hypercalcaemia

A

MEN1/ 2
-Will almost always have developed a parathyroid adenoma with hypercalcaemia at a young age

Familial isolated hyperparathyroidism
-Adenoma as in primary hyperparathyroidism

36
Q

what is familial hypocalciuric hypercalcaemia

A

condition where a deactivating mutation in the calcium sensing receptor (CaSR) causes increased PTH production + low calcium in urine = increased serum calcium

37
Q

what inheritance pattern does FHH follow

A

autosomal dominant

38
Q

what is the severity of FHH

A

usually benign/ asymptomatic

39
Q

what are the tests for FHH

A

Mild Hypercalaemia
Reduced urine calcium excretion
PTH may be (marginally) elevated
Genetic Screening

40
Q

what are the signs and symptoms of hypocalcaemia

A 
Paraesthesia - fingers, toes, perioral
Muscle cramps, tetany
Muscle weakness
Fatigue
Bronchospasm or laryngospasm
Fits
Chovsteks sign (tapping over facial nerve)
Trousseau sign (carpopedal spasm)
ECG: QT prolongation (risk of R on T, VF)
41
Q

what is the treatment for acute hypocalcaemia

A

IV calcium gluconate (in saline or dextrose)

42
Q

what are the possible causes of hypocalcaemia

A

congenital - DiGeorge (babies have no PTH)
destruction (surgery, radiotherapy, malignancy)
autoimmune
hypomagnesaemia (functional hypoparathyroidism)
idiopathic

43
Q

what is the long term management for hypocalcaemia

A

calcium supplement

vit D tablets

44
Q

how is hypomagnesaemia related to hypocalcaemia

A

calcium release from cells is dependent on magnesium
in magnesium deficiency intracellular calcium is high
PTH release in inhibited
skeletal and muscle receptors less sensitive to PTH

45
Q

what can cause hypomangesaemia

A 
Alcohol
Drugs
-Thiazide
-PPI
GI illness
Pancreatitis
Malabsorption
46
Q

what is pseudohypoparathyroidism

A

genetic defect (GNAS 1) that causes low calcium but PTH concentrations are high

caused by PTH resistance

47
Q

what are the features of pseudohypoparathyroidism

A 
Bone abnormalities (McCune Albright)
Obesity
Subcutanous calcification 
Learning Disability
Brachdactyly (4th metacarpal- short)
48
Q

what is pseudo-pseudohypoparathyroidism

A

Albright’s Herditary Osteodystrophy with no alteration in PTH action so normal calcium

49
Q

what can cause malabsorption of vit D

A

gastric surgery, coeliac disease, liver disease, pancreatic failure

50
Q

what can cause rickets/ osteomalacia (vit D deficiency)

A 
dietary deficiency 
malabsorption 
chronic renal failure 
lack of sunlight 
drugs (anticonvulsants)
51
Q

what are the clinical signs of osteomalacia

A 
low calcium
muscle wasting (proximal myopathy)
dental defects (caries, enamel)
bone- tenderness, fractures, rib deformity, limb deformity 
waddling gate
52
Q

what are common features of chronic renal disease

A

vit D deficiency

secondary hyperparathyroidism

53
Q

what are the long term consequences of vitamin D deficiency

A

bone disease- demineralisation/ fractures
osteomalacia/ rickets

malignancy (esp colon), heart disease, diabetes

54
Q

what is the chronic treatment for vit d deficiency

A

vit D tablets, combined calcium + vit D

55
Q

what causes vitamin D resistant rickets

A

PHEX or FGF23 gene mutation

FGF 23 regulates phosphate levels in plasma and is secreted by osteocytes in response to calcitriol

56
Q

what are the features of vitamin D resistant rickets

A

Low phosphate

High Vitamin D

57
Q

what is the treatment for vitamin D resistant rickets

A

phosphate and Vit D supplements +/- surgery

58
Q 
name the disease:
Ca ++
PTH ++
AP N(+)
Phos -
A

primary parathyroidism

59
Q 
name the disease:
Ca ++
PTH ---
AP +++
Phos N
A

malignancy

60
Q 
name the disease:
Ca +
PTH N/+
AP N
Phos N
A

FHH

61
Q 
name the disease:
Ca --
PTH --
AP N
Phos +/N
A

hypoparathyroidism

62
Q 
name the disease:
Ca --
PTH +
AP ++
Phos -
A

osteomalacia

63
Q 
name the disease:
Ca N(+)
PTH N
AP ++
Phos N
A

pagets

Endocrinology (46 decks)

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