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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
what is the action of calcitonin
inhibits OC bone resorption when plasma Ca is very high NO ROLE IN DAY-DAY plasma Ca resorption
26
what are the main actions of hypercalcaemia
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
what are the hormonal causes of hypercalcaemia
primary hyperparathyroidism hypervitaminosis D paraneoplastic
28
name some non-hormonal causes of hypercalcaemia
renal failure milk-alkali syndrome drugs (thiazides, lithium)
29
what happens in HYPOcalcaemia
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
what are the causes of hypoparathyroidism and therefore hypocalcaemia
post surgical AI psuedo (PTH resistance) idiopathic
31
what are the causes of hypocalcaemia through hypovitaminosis D
dietary deficiency | rickets/osteomalacia
32
what kind of organ dysfunction can cause hypocalcaemia
renal loss | GI malabsorption
33
what is the endocrine response to non-hypoparathyroid hypocalcaemia
secondary hyperparathyroidism
34
what is the condition where there is a heterozygous inactivating mutation in the calcium sensing receptor
familial benign hypocalciuric hyper calcaemia
35
what is the condition where there is a homozygous inactivating mutation in the calcium sensing receptor
LETHAL in infancy results in severe hypercalcaemia
36
what is pseudohypoparathyroidism
PTH resistance resulting in hypocalcaemia with elevated PTH
37
which GI dysfunctions may cause abnormal vit D/Ca absorption
shot bowel malabsorptionsydromes IBS
38
what can a genetic renal calcium leak cause
hypercalciuria with secondary hyperparathyroidism
39
what might cause primary hyperparathyroidism
adenoma hyperplasia (malignancy rare)
40
what are the characteristics of primary hyperparathyroidism
hypercalcaemia with elevated PTH and hypercalciuria fractures, kidney stones
41
what might cause excessive production of 1,25 (OH) vit D3
granulomas | abnormal lymph tissue
42
excess production of corticol in the zona fasciulata caused by adrenal tumour, pituitary tumours or ectopic ACTH production
Cushing's
43
endocrine hypertension caused by excess secretion of aldosterone from zona glomerulosa
Conn's syndrome
44
mineralocorticoid produced in the zona glomerulosa
aldosterone
45
hormone produced in the zona fasciculata
cortisol
46
acute cause of addison's
sudden withdrawal of long term steroids
47
chronic causes of addison's
autoimmune adrenalitis
48
symptoms phaechromocytoma
sweating tachycardia nad hypertension
49
primary adrenal insufficiency
Addison's
50
androgen deficiency and/or impaired sperm produciton
primary hypogonadism
51
Turners
``` 46 XO primary amenorrhoea lymphoedema of the handsand feet growth failure neck webbing cubitis valgus ```
52
Premature ovarian failure
hypergonadotrophic amenorrhoea female <40 generally idiopathic
53
whic amino acids are the aminoacid dervatives made from
tyrosine
54
what are the features of severe hypercalcaemia
- serum Ca >3.5 mmol/l - impaired tubular resorption - extracellular volume depletion - decreased GFR and impaired Ca clearance - increased PTHrP levels
55
whihc three hormones are involved in calcium homeostasis
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
causes of hypercalcaemia
primary hyperparathyroidism malignancy secondary (compensatory to hypocalc) tertiary (following long term hypo calc)
57
name 3 causes of primary hyperparathyroidism
adenoma hyperplasia carcinoma

Nutrition (11 decks)

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