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Y2 RnU > Calcium and Sodium Homeostasis > Flashcards

Calcium and Sodium Homeostasis Flashcards

1
Q

What is hypercalcaemia when PTHrP causes it

A

Known as humoral hypercalcaemia of malignancy when PTHrP is the cause

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2
Q

What cytokines produced by Multiple Myeloma activate osteoclasts

A

RANKL, IL-3, IL-6

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3
Q

One common sign of Multiple Myeloma

A

Pepperpot skull

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4
Q

How do granulomas cause hypercalcaemia

A
  • Increased calcium concentration with PTH concentration
    • Due to hydroxylation of Vit D in granuloma
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5
Q

what drugs can cause hypercalcaemia

A

Li, thiazide

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6
Q

What endocrine diseases can cause hypercalcaemia

A

(thyrotoxicosis, Addison’s disease)

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7
Q

Neuromuscular manifestations of hypocalcaemia

A
  • Numbness and paraesthesia in fingertips, toes and around mouth
  • Anxiety and fatigue
  • Muscle cramps, carpo-pedal spasm, bronchial or laryngeal spasm
  • Seizures
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8
Q

How does hypo and hyper calcaemia affect QT interval

A

Hypo=> prolongs, vv

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9
Q

effect of hypocalcaemia on eyes

A

Cloudiness of eyes lens and cataract

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10
Q

Causes of factitious hypocalcaemia

A
  • Acute phase response (low albumin)
  • Malnutrition or malabsorption
    • Protein deficiency in diet
  • Liver disease
    • Reduced liver synthesis of albumin
  • Nephrotic syndrome
    • Albumin lost in urine
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11
Q

Causes of VDRR

A
  • Deficient 1-hydroxylase (Vitamin D-resistant rickets type 1, VDRR type 1)
  • Deficient receptor for calcitriol(Vitamin D- resistant rickets Type 2, VDRR type 2)
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12
Q

Other causes of rickets apart of VDRR

A
  • Hypophosphataemic rickets
    • Low Serum Phosphate→ Impaired mineralisation
    • Excessive urine phosphate loss
    • Phosphaturic hormone (FGF23)/ PHEX mutations

Hypophosphatasia ( low Alk Phosphatase)

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13
Q

Causes of 1* hypoparathyroidism

A
  • Surgical damage or removal ( relatively common but usually transient)
  • Suppressed secretion
    • May be due to low Mg 2+,which is required for PTH action
      • Caused by drugs, lost through GI tract etc.
  • Inherited ( dont really need to know )
    • Developmental Parathyroid Problems
    • Genetic/ familial disorders eg. DiGeorge Syndrome
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14
Q

Treatment of hypoparathyroidism

A
  • IV calcium may be required in acute situations
  • Normally oral calcium and Vit D are given (Mg sometimes in less serious case)
    • Vitamin D may be given in various forms
      • By IM injection if malabsorption is present (can give large bolus to repair more quickly) or stores are required to be repleted more quickly
      • As 1 OH form if renal function is impaired
    • Close monitoring of plasma calcium concentration necessary
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15
Q

What does reduced Cardiac output result in

A

Reduced Effective Circulating Volume

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16
Q

3 diseases causing interstitial oedema and how does this relate to water and salt gain/loss. Is hyponatraemia here hypervolaemic or hypo

A

Heart failure, liver failure, Nephrotic syndrome
water> salt gain
HYPER

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17
Q

What does hypothyroidism cause wrt water balance

A

pure water gain

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18
Q

common cause of malignant ectopic secretion of ADH

A

Small Cell Lung Carcinoma

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19
Q

Most common cause of hypernatremia

A

Hypovolaemia

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20
Q

What is a more likely cause of CDI

A

Head injury compared to pit tumour

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21
Q

Metabolic causes of NDI

A

Hyokalemia or Hypercalcaemia

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22
Q

How to treat NDI

A

Supraphysiological ADH, diuretics, NSAIDs

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23
Q

What is cholecalciferol and where is it found and converted

A

Vitamin D, gets converted by 25 hydroxylase in the liver to calcidiol

24
Q

What enzyme is present in the kidney and what does it do wrt vitamin D metabolism

A

1a-hydroxylase
Converts 25(OH) Vit D to 1,25 (OH)2 VItamin D

25
What is calcitonin a useful marker of
Thyroid medullary cancer
26
what are the manifestation of hypercalcemia
“Stones, bones. abdominal moans, and psychic groans” Muscle weakness (and constipation) ⇒both striated and smooth muscles Anorexia, nausea, vomiting, mood change, depression Abdominal pain Renal effects- dehydration and renal stone formation,
27
What are the possible causes of hypercalcemia
Primary hyperparathyroidism - 90% solitary (benign)adenoma, some hyperplasia (of one or both glands), carcinoma
28
How are PTH, phosphate and bicarbonate, ALk Phosp levels in primary hyperparathyroidism What causes these effects on phosphate and bicarbonate?
- **inappropriately increased PTH** - PTH not always high, may be high-normal - Reduced serum phosphate and HCO3- (see below) also causes complexed calcium to be freed up and released into ionised fraction due to inhibition of proximal tubule reabsorption of Po4- and bicarbonate Alk phos high or normal due to bonr resorption
29
Effect of primary hyperparathyroidism on pH level and what effect doe this have on the body?
Causes mild acidosis due to reduced uptake of bicarbonate, s which causes calcium to be leached from the bone, decreases calcium binding to albumin
30
Treatment of hyperparathyroidism
FIRST LINE is to rehydrate by IV - brings calcium concentration down Can give loop diuretics like furosemide to inhibit distal ca2+ reabsorption Can also give bisphosphonates- inhibit osteoclast action and hence bone resorption (Key drug for longer-term control after re-hydration)
31
What drug can inhibit osteoclast action
Calcitonin
32
What drugs can inhibit conversion of Vitamin D to calcitriol
Glucocorticoids
33
How do metastatic tumours cause hypercalcaemia
They locally stimulate bone resorption via osteoclast activation
34
diagnosis of hypercalcaemia from malignancy- what are the common investigations
Raised Ca2+ with suppressed PTH , high phosphate, high alk phosp
35
treatment of hypercalcaemia from malignancy
Rehydrate patient, use bisphosphonates to lower calcium in blood , treat underlying malignancy
36
What problems can hypocalcemia cause apart for mental and neuromuscular and cardiac functions
Eye probelms- cloudiness of eye lens and cataract
37
What is the most readily measured vitamin D metabolite
25-hydroxy-vitamin D released into plasma from the liver
38
how does Vitamin D deficiency affect phosphate
Reduces gut absorption of calcium which results in lower calcium levels in blood and higher PTH levels which result in increased bone resorption and increased phosphate wasting
39
diff between osteoporosis and osteomalalcia
less bone but histologically normal vs abnormal histology with wide seams of uncalcified osteoid Essentially normal biochemistry vs Abnormal biochemistry→ low plasma vit D3, low calcium, high PTH
40
Sim between osteoporosis and osteomalalcia
Both have reduced bone density and susceptibility to fracture
41
What are the main causes of euvolaemic hyponatraemia and is there water or salt loss or gain
SIADH, hypothyroid, iatrogenic. pure water gain
42
What can dilutional hyponatraemia cause
Cerebral oedema
43
What are common causes of more salt loss than water loss Is this hypo or hypervolaemic
diarrhea can be salt rich HYPO
44
What are two non malignant causes of ectopic SIADH secretion
TB and pneumonia
45
What drugs can cause SIADH
thiazide diuretic, carbamazepine, amitriptyline
46
Why should hyponatraemia be corrected slowly
- Central Pontine Myelinolysis - Devastating/fatal condition associated with rapid correction of hyponatraemia → due to nerve fibres in pons losing their myelin sheath
47
Treatment of hypervolaemic hyponatraemia
Diuretics like furosemide, fluid restriction
48
Treatment of euvolaemic hyponatraemia
- Treat underlying cause - Stop IV fluids - Thyroxine replacement - Fluid restriction!!! - Down to 500ml/day - Rarely demeclocycline
49
What is the proportion of water to salt in colon
Musch higher proportion of water as salt is already absorbed in the small bowel
50
What infections can cause SIADH and DI
meningitis and encephalitis
51
What drug can cause NDI
Lithium carbonate which blocks receptors in nephron
52
Treatment for DI
- DDAVP exists ( nasal spray) - Works in **CDI** - For NDI - Supraphysiological ADH may work - Diuretics - NSAIDs
53
Does addison's result in hypo or hypernatraemia
hyponatraemia
54
Should rehydration be given for DI
No
55
What are the effects of PTH on calcium levels and how
Increases - More calcium resorbed in Kidney (LOH, DCT and CD) - Vit D3 activated to stimulate ca2+ absorption in gut - Bone resorption

Y2 RnU (9 decks)

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