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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
Q

What is calcitonin a useful marker of

A

Thyroid medullary cancer

26
Q

what are the manifestation of hypercalcemia

A

“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
Q

What are the possible causes of hypercalcemia

A

Primary hyperparathyroidism - 90% solitary (benign)adenoma, some hyperplasia (of one or both glands), carcinoma

28
Q

How are PTH, phosphate and bicarbonate, ALk Phosp levels in primary hyperparathyroidism

What causes these effects on phosphate and bicarbonate?

A
  • 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
Q

Effect of primary hyperparathyroidism on pH level and what effect doe this have on the body?

A

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
Q

Treatment of hyperparathyroidism

A

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
Q

What drug can inhibit osteoclast action

A

Calcitonin

32
Q

What drugs can inhibit conversion of Vitamin D to calcitriol

A

Glucocorticoids

33
Q

How do metastatic tumours cause hypercalcaemia

A

They locally stimulate bone resorption via osteoclast activation

34
Q

diagnosis of hypercalcaemia from malignancy- what are the common investigations

A

Raised Ca2+ with suppressed PTH , high phosphate, high alk phosp

35
Q

treatment of hypercalcaemia from malignancy

A

Rehydrate patient, use bisphosphonates to lower calcium in blood , treat underlying malignancy

36
Q

What problems can hypocalcemia cause apart for mental and neuromuscular and cardiac functions

A

Eye probelms- cloudiness of eye lens and cataract

37
Q

What is the most readily measured vitamin D metabolite

A

25-hydroxy-vitamin D released into plasma from the liver

38
Q

how does Vitamin D deficiency affect phosphate

A

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
Q

diff between osteoporosis and osteomalalcia

A

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
Q

Sim between osteoporosis and osteomalalcia

A

Both have reduced bone density and susceptibility to fracture

41
Q

What are the main causes of euvolaemic hyponatraemia and is there water or salt loss or gain

A

SIADH, hypothyroid, iatrogenic. pure water gain

42
Q

What can dilutional hyponatraemia cause

A

Cerebral oedema

43
Q

What are common causes of more salt loss than water loss
Is this hypo or hypervolaemic

A

diarrhea can be salt rich
HYPO

44
Q

What are two non malignant causes of ectopic SIADH secretion

A

TB and pneumonia

45
Q

What drugs can cause SIADH

A

thiazide diuretic, carbamazepine, amitriptyline

46
Q

Why should hyponatraemia be corrected slowly

A
  • Central Pontine Myelinolysis
    • Devastating/fatal condition associated with rapid correction of hyponatraemia → due to nerve fibres in pons losing their myelin sheath
47
Q

Treatment of hypervolaemic hyponatraemia

A

Diuretics like furosemide, fluid restriction

48
Q

Treatment of euvolaemic hyponatraemia

A
  • Treat underlying cause
    • Stop IV fluids
    • Thyroxine replacement
  • Fluid restriction!!!
    • Down to 500ml/day
  • Rarely demeclocycline
49
Q

What is the proportion of water to salt in colon

A

Musch higher proportion of water as salt is already absorbed in the small bowel

50
Q

What infections can cause SIADH and DI

A

meningitis and encephalitis

51
Q

What drug can cause NDI

A

Lithium carbonate which blocks receptors in nephron

52
Q

Treatment for DI

A
  • DDAVP exists ( nasal spray)
    • Works in CDI
  • For NDI
    • Supraphysiological ADH may work
    • Diuretics
    • NSAIDs
53
Q

Does addison’s result in hypo or hypernatraemia

A

hyponatraemia

54
Q

Should rehydration be given for DI

A

No

55
Q

What are the effects of PTH on calcium levels and how

A

Increases
- More calcium resorbed in Kidney (LOH, DCT and CD)
- Vit D3 activated to stimulate ca2+ absorption in gut
- Bone resorption

RnU (9 decks)

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