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Nutrition > General endocrine > Flashcards

General endocrine Flashcards

1
Q

what are the causes of hypocalcaemia

A 
hypoparathyroidism
impaired PTH secretion
target organ resistance
vit D disorders
pancreatitis
hypomagnesaemia
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2
Q

what is defined as hypocalcaemia

A

serum Ca <1.8

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3
Q

which other cation is intimately involved with calcium metabolism

A

magnesium

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4
Q

how does PTH decrease excretion of Ca

A

increases reabsorption in the DCT

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5
Q

list the funcitons of Ca in the body

A 
cell signalling
clotting mechanisms
muscular contraction
formation of calcified tissues
integrity and permeability or the cell wall
cell adhesion
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6
Q

what is the primary purpose of Ca homeostasis

A

to maintain constant blood calcium concentration

hyperkalaemia can be fatal

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7
Q

what are the principal organ systems in the regulation of Ca

A

gut
bone
kidneys

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8
Q

what are the three hormones involved in the regulation of calcium

A

PTH
Vit D
Calcitonin

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9
Q

what methods of getting calcium in are there

A

intestinal absorption of bone

bone resorption

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10
Q

how is calcium taken out of the body

A

renal excretion

bone formation

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11
Q

what makes vit D3 a hormone

A

made in one plaace and acts in another

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12
Q

what stage of vit D synthesis takes place in the skin

A

7-dehydrocholesterol –> vit D3

this conversion requires UV light

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13
Q

what stage of vit D synthesis takes place in the liver

A

vit D3 –> 25 (OH)vitD3

hydroxylased by 25-hydroxylase

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14
Q

which stage of vit D synthesis takes place in the kidney

A

25(OH) D3 –> 1,25(OH)D3
ACTIVE COMPOUND

1 alpha hydroxylase

regulated by PTH

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15
Q

name 3 sources of vit D3

A

self gen
in food
in supplement

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16
Q

name the function of vit D in the gut

A

increases transepithelial transport of Ca and PO4 in the small intestine

this increases serum Ca

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17
Q

what is the function of vit D3 in bone

A

stimulates the terminal differentiation of OC directly and via OBs

this increases serum CA

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18
Q

waht is the function of vit D3 in the parathyroid gland

A

inhibits the transcription of PTH gene

this decreases production and therefore provides NEGATIVE FEEDBACK

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19
Q

what is the action of PTH on bone

A

increases resorption of bone

this increases serum Ca

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20
Q

what is the action of PTH on the kidneys

A

Stimulates tubular resorption of Ca

stimulates 1alphahydroxylas and therefore indirectly increases intestinal absorption of Ca

these all increase serum Ca

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21
Q

what stimulates PTH secretion

A

falling Ca levels

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22
Q

what type of receptor is the PTH receptor

A

G protein coupled

also binds PTHrP with equal affinity

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23
Q

describe the calcium sensing receptor found in the parathyroids and kidneys

A

7 transmembrane spanning protein

binds Ca extracellularly
coupled to signalling pathyway via G proteins

24
Q

where is calcitonin synthesised

A

parafollicular cells (C-cells) of the thyroid gland

25
Q

what is the action of calcitonin

A

inhibits OC bone resorption when plasma Ca is very high

NO ROLE IN DAY-DAY plasma Ca resorption

26
Q

what are the main actions of hypercalcaemia

A

BONES, fracture risk
GROANS,
THRONES, anorexia, constipation, N&V, diuresis, impaired concentrating ability, dehydration, kidney stones
PSYCHIATRIC OVERTONES lethargy, depression, dcr alertness, confusion, ocma

(CV: exacerbate HTN, shortern QT)

27
Q

what are the hormonal causes of hypercalcaemia

A

primary hyperparathyroidism
hypervitaminosis D
paraneoplastic

28
Q

name some non-hormonal causes of hypercalcaemia

A

renal failure
milk-alkali syndrome
drugs (thiazides, lithium)

29
Q

what happens in HYPOcalcaemia

A

lowered threshold of depolarisation -> INCREASED ACTIVITY

  • perioral tingling and parasthesia
  • tetany
  • facial spasms (Chvostek’s sign from tapping facial nerve)
  • Trousseau’s sign
  • hyperactive tendon reflexes
  • laryngospasm
  • prolongs QT and other cardiac arrythmias
  • grand mal seizures
  • cataracts
  • basal ganglia calcification
30
Q

what are the causes of hypoparathyroidism and therefore hypocalcaemia

A

post surgical
AI
psuedo (PTH resistance)
idiopathic

31
Q

what are the causes of hypocalcaemia through hypovitaminosis D

A

dietary deficiency

rickets/osteomalacia

32
Q

what kind of organ dysfunction can cause hypocalcaemia

A

renal loss

GI malabsorption

33
Q

what is the endocrine response to non-hypoparathyroid hypocalcaemia

A

secondary hyperparathyroidism

34
Q

what is the condition where there is a heterozygous inactivating mutation in the calcium sensing receptor

A

familial benign hypocalciuric hyper calcaemia

35
Q

what is the condition where there is a homozygous inactivating mutation in the calcium sensing receptor

A

LETHAL in infancy

results in severe hypercalcaemia

36
Q

what is pseudohypoparathyroidism

A

PTH resistance resulting in hypocalcaemia with elevated PTH

37
Q

which GI dysfunctions may cause abnormal vit D/Ca absorption

A

shot bowel
malabsorptionsydromes
IBS

38
Q

what can a genetic renal calcium leak cause

A

hypercalciuria with secondary hyperparathyroidism

39
Q

what might cause primary hyperparathyroidism

A

adenoma
hyperplasia
(malignancy rare)

40
Q

what are the characteristics of primary hyperparathyroidism

A

hypercalcaemia with elevated PTH and hypercalciuria

fractures, kidney stones

41
Q

what might cause excessive production of 1,25 (OH) vit D3

A

granulomas

abnormal lymph tissue

42
Q

excess production of corticol in the zona fasciulata caused by adrenal tumour, pituitary tumours or ectopic ACTH production

A

Cushing’s

43
Q

endocrine hypertension caused by excess secretion of aldosterone from zona glomerulosa

A

Conn’s syndrome

44
Q

mineralocorticoid produced in the zona glomerulosa

A

aldosterone

45
Q

hormone produced in the zona fasciculata

A

cortisol

46
Q

acute cause of addison’s

A

sudden withdrawal of long term steroids

47
Q

chronic causes of addison’s

A

autoimmune adrenalitis

48
Q

symptoms phaechromocytoma

A

sweating tachycardia nad hypertension

49
Q

primary adrenal insufficiency

A

Addison’s

50
Q

androgen deficiency and/or impaired sperm produciton

A

primary hypogonadism

51
Q

Turners

A 
46 XO
primary amenorrhoea lymphoedema of the handsand feet
growth failure
neck webbing
cubitis valgus
52
Q

Premature ovarian failure

A

hypergonadotrophic amenorrhoea
female <40
generally idiopathic

53
Q

whic amino acids are the aminoacid dervatives made from

A

tyrosine

54
Q

what are the features of severe hypercalcaemia

A
  • serum Ca >3.5 mmol/l
  • impaired tubular resorption
  • extracellular volume depletion
  • decreased GFR and impaired Ca clearance
  • increased PTHrP levels
55
Q

whihc three hormones are involved in calcium homeostasis

A

PTH - inc resorption in the kidneys and bones to increase serum conc
Vit D - increased absorption in the gut to increase serum concentrations
Calcitonin

56
Q

causes of hypercalcaemia

A

primary hyperparathyroidism
malignancy
secondary (compensatory to hypocalc)
tertiary (following long term hypo calc)

57
Q

name 3 causes of primary hyperparathyroidism

A

adenoma
hyperplasia
carcinoma

Nutrition (11 decks)

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