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Year 2 - Endocrine > Calcium homeostasis clinical > Flashcards

Calcium homeostasis clinical Flashcards

1
Q

Acute hypocalcaemia defined as serum calcium

A

2.2mmol/l

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2
Q

Symptoms (5) /signs (3) of acute hypocalcaemia

A

Symptoms

  • paraesthesia
  • tetany (muscle spasms)
  • seizures
  • carpopedal spasms (spasms in the hands and feet)
  • cardiac hyperexcitability
  • confusion

Signs

  • Chvostek’s sign
  • Trousseau’s sign
  • hypotension
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3
Q

Chovstek’s and trousseau’s sign are signs of acute hypocalcaemia - describe what you see in them

A

Chvostek’s sign - twitching of facial muscles in response to tapping over the area of the facial nerve

Trousseau’s sign - inflating the blood-pressure cuff to a level above systolic pressure for 3 minutes; in the absence of blood flow, hypocalcemia and subsequent neuromuscular irritability induces flexion of the wrist and metacarpal joints, adduction of thumb and fingers

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4
Q

Symptoms/signs of chronic hypocalcaemia (7)

A 
Papilloedema, 
cataracts, 
basal ganglia calcifications, 
Dry skin/dermatitis
Brittle hair/nails/teeth
Dementia
Anxiety/depression
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5
Q

What nerve can get damaged during a thyroidectomy + what can this present with

A

Recurrent laryngeal nerve

Hoarse voice

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6
Q

Causes of hypocalcaemia (4)

A

Vitamin D deficiency

Iatrogenic post-surgical hypoparathyroidism - disturbed after thyroidectomy or parathyroidectomy

Magnesium deficiency -interferes with the secretion and action of PTH

Drug induced hypocalcaemia

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7
Q

Causes of hypoparathyroidism (i.e. low PTH secretion) (6)

A

Post surgical - thyroidectomy, parathyroidectomy

Genetic disorders (RARE) - e.g. digeorge syndrome

Autoimmune destruction of parathyroids

Radiation induced destruction

Infiltration by iron or copper

hypomagnesaemia

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8
Q

Drugs that induce hypocalcaemia (4)

A

Bisphosphonates - inhibit bone breakdown so less calcium released into blood

PPI - causes hypomagnesemia

Phenytoin (anticonvulsant)

Calcium chelating agents - EDTA

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9
Q

Biochemical investigations used to detect abnormalities of calcium control (hypo/hypercalcaemia) (8)

+ heart investigation (1)

+ imaging investigations (3)

A 
Serum calcium
Serum albumin
Plasma intact PTH 
Serum magnesium 
Serum phosphorus
U+Es
Serum 25-hydroxyvitamin D 
24 hr urinary calcium

ECG - prolonged QT may indicate hypocalcaemia

Abdo XR/ CT
Renal ultrasound

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10
Q

What is hungry bone syndrome

A

A cause of severe hypocalcaemia

  • seen after parathyroidectomy (or thyroidectomy)
  • calcium is rapidly taken from the circulation and deposited in stores in the bones as there’s no PTH so reduced bone resorption (breakdown)
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11
Q

If serum calcium indicates hypocalcaemia, what investigation next

A

Serum PTH

- to see if it’s hypoparathyroidism

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12
Q

In hypocalcaemia, what happens to the following

  • Serum calcium
  • Serum albumin
  • Plasma intact PTH
  • Serum magnesium
A

serum adjusted calcium - low, adjusted for albumin

serum albumin - NORMAL; not low because if it was low then total serum calcium would actually be normal for the amount of albumin

PTH - DEPENDS on cause, low if cause is hypoparathyroidism, high if cause is vitamin D deficiency/ renal failure

serum magnesium - LOW/NORMAL (low if hypocalcaemia due to magnesium deficiency; normal if due to hypoarathyroidism)

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13
Q

What form of calcium is a more accurate reflection of calcium levels

A

IONISED CALCIUM as it’s not affected by plasma albumin levels

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14
Q

What is pseudohypoparathyroidism

A

presents in childhood, refers to a group of heterogeneous disorders defined by kidney and bone unresponsiveness to PTH (PTH resistance)

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15
Q

Pseudohypoparathyroidism is biochemically characterised by (3)

A

Low Ca2+
High PTH
High phosphate

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16
Q

Treatment of mild hypocalcaemia (asymptomatic, >1.9mmol/l) (4)

A

Oral calcium carbonate
Oral calcitriol

Oral vitamin D if deficient
Oral magnesium if deficient

17
Q

Treatment of severe hypocalcaemia (symptomatic, <1.9mmol/l) (3)

A

IV CALCIUM GLUCONATE
IV magnesium if severely deficient
Treat respiratory alkalosis if present + any other underlying cause

18
Q

If have renal impairment, dietary vitamin D lacks conversion into its active form as the kidney is required in this process so patients need to take active forms of vitamin D - name an active form

A

Calcitriol

19
Q

Acute hypercalcaemia that’s often asymptomatic and doesn’t require urgent correction is defined as serum calcium <

Acute hypercalcaemia that’s beginning to be symptomatic but still tolerable; however still indicating treatment is defined as what serum calcium conc =

Acute hypercalcaemia that required urgent correction due to risk of arrhythmia and coma is defined as serum calcium >

A

<3mmol/l

3-3.5mmol/l

> 3.5mmol/l

20
Q

Causes of hypercalcaemia (7)

A 
Hyperparathyroidism
Ectopic tumours producing excess PTH like hormone
Multiple myeloma - blood cancer
Bone metastases from a primary
Familial hypocalciuric hypercalcemia
Vitamin D intoxication
Drug-induced
21
Q

Symptoms (7) /signs (1) of more moderate-severe hypercalcaemia

mild is asymptomatic

*think of the memorable phase for hypercalcaemia

A

Symptoms

  • lethargy/fatigue
  • CONFUSION
  • irritability
  • ABDO PAIN
  • BONE PAIN
  • constipation
  • muscle weakness

Signs
-kidney STONES (nephrolithiasis)

22
Q

Symptoms/signs of hypercalcaemia or primary hyperparathyroidism is characterised by what memorable phrase

A

Bones, renal stones, abdo groans + psychic moans

  • bone pain
  • kidney stones
  • abdo pain
  • confusion/lethargy
23
Q

Patients presenting with hypercalcaemia may have what pre-existing bone condition

A

osteoporosis

-bone loss occurs as result of bone resorption due to excess PTH

24
Q

What primary tumours may metastasise and can cause hypercalcaemia (2)

A

Breast

Lung

25
Q

In primary hyperparathyroidism, what happens to the following

  • Serum calcium
  • Plasma intact PTH
  • serum phosphorus
A

calcium elevated
PTH elevated
phosphorus low

26
Q

What cancer may be screened for in blood if hypercalcaemic

A

Multiple myeloma

27
Q

If serum calcium high and PTH high, cause is likely to be

A

primary hyperparathyrodism

familial hypocalciuric hypercalcaemia - chronically elevated serum calcium and reduced calcium excretion

28
Q

If serum calcium high but PTH low, cause likely to be

A

Malignancy - ectopic tumour producing PTH mimic

Drug induced

29
Q

Hyperfunction of the parathyroids (hyperparathyroidism) is associated with what genetic syndrome

A

MEN1, 2A

30
Q

Primary hyperparathyroidism is usually caused by what pathology

A

Parathyroid adenoma

-mostly asymptomatic

31
Q

Imaging investigations of hypercalcaemia (think bones, stones, groans and bones) (2)

A

Abdo XR/ CT

Renal ultrasound

32
Q

24hr urinary calcium finding in primary hyperparathyroidism v familial hypocalciuric hypercalcaemia (FHH)

A

PHPT - high

FHH - low due to condition being characterised as reduced excretion of calcium

33
Q

Indications for surgery in primary hyperparathyroidism (4)

A

Symptomatic
Serum calcium 2.85mmol/l
Osteoporosis
Kidney stones

34
Q

Medical (1)/surgical (1) treatment of symptomatic primary hyperparathyroidism

A

Parathyroidectomy - first line

Medical
-Cinacalcet - mimics calcium so has the effect of calcium on the calcium sensing receptors on chief cells of the parathyroid gland –> decreasing PTH secretion and subsequently decreasing plasma Ca2+

35
Q

What is familial hypocalciuric hypercalcaemia caused by

A

Autosomal dominant disorder of the calcium sensing receptor
-loss of function of this receptor on parathyroid tissue –> decreases the receptor’s sensitivity to calcium –> slow, chronic calcium elevation, allowing patients to adapt to it

36
Q

What is familial hypocalciuric hypercalcaemia characterised by (2)

A

hypercalcemia but reduced urinary excretion of calcium

  • high serum Ca2+
  • low urine Ca2+
37
Q

Name some malignant tumours that cause hypercalcaemia (4)

A

Humoral hypercalcaemia of malignancy (characterised by tumour secretion of parathyroid hormone-related peptide [PTHrP]) - e.g. breast, multiple myeloma

Local osteolytic hypercalcaemia (characterised by local release of factors, including PTHrP, by bony metastases that promote osteoclast function)

Calcitriol (1,25-dihydroxyvitamin D) secreting lymphomas

Ectopic hyperparathyroidism (characterised by tumour production of PTH) - RARE

38
Q

Treatment of calcitriol (1,25-dihydroxyvitamin D)-secreting lymphomas that cause hypercalcaemia

A

Glucocorticoids

39
Q

Treatment of humoral hypercalcaemia of malignancy and local osteolytic hypercalcaemia

A

IV bisphophonates

Year 2 - Endocrine (21 decks)

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