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endocrine > Clinical calcium homeostasis > Flashcards

Clinical calcium homeostasis Flashcards

The title says it all really

1
Q

What are the causes of hypocalcaemia?

A
  • Disruption to the thyroid gland following total thyroidectomy (may be temporary or permanent)
  • Following selective thyroidectomy (usually transient and mild)
  • Severe vitamin D deficiency (common)
  • Magnesium deficiency (proton pump inhibitors e.g. omeprazole can causes this)
  • Cytotoxic drug-induced hypocalcaemia
  • Pancreatitis, rhabdomyolysis and large volume blood transfusion
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2
Q

When does sympptoms of hypocalcaemia start to develop?

A

when serum calcium falls below 1.9mmol/L (this threshold does vary and is dependent of the rate of fall)

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3
Q

What are the symptoms of acute hypocalcaemia?

A 
□ Neuromuscular irritability (tetany)
	® Paraesthesia
	® Muscle twitching
	® Carpopedal spasm 
	® Trousseau's sign
	® Chvostek's sign
	® Seizures
	® Laryngospasm
	® Bronchospasm 
□ Cardiac
        ® Prolonged QT interval 
	® Hypotension
	® Heart failure 
	® Arrhythmia 
	® Papilledema
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4
Q

What are the chronic signs and symptoms of hypocalcaemia?

A 
□ Ectopic calcification (basal ganglia)
□ Extrapyramidal signs
□ Parkinsonism
□ Dementia 
□ Subcapsular cataracts
□ Abnormal dentition  
□ Dry skin
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5
Q

What are the investigations for hypocalcaemia?

A 
○ ECG
○ Serum calcium
○ Albumin
○ Phosphate
○ PTH
○ U&Es
○ Vitamin D
○ Magnesium
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6
Q

What will the results be if someone has hypoalbuminemia?

A
  • Low total calcium
  • Normal ionised calcium
  • Normal phosphate
  • Normal PTH
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7
Q

What will the results be if someone has alkalosis?

A
  • Normal total calcium
  • Low ionised calcium
  • Normal phosphate
  • Normal/ high PTH
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8
Q

What will the results be if someone has vitamin D deficiency?

A
  • Low total calcium
  • Low ionised calcium
  • Low phosphate
  • High PTH
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9
Q

What will the results be if someone has chronic renal failure?

A
  • Low total calcium
  • Low ionised calcium
  • High phosphate
  • High PTH
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10
Q

What will the results be if someone has hypoparathyroidism?

A
  • Low total calcium
  • Low ionised calcium
  • High phosphate
  • Low PTH
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11
Q

What will the results be if someone has pseudohypoparathyroidism?

A
  • Low total calcium
  • Low ionised calcium
  • High phosphate
  • High PTH
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12
Q

What will the results be if someone has acute pancreatitis?

A
  • Low total calcium
  • Low ionised calcium
  • Low/ normal phosphate
  • High PTH
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13
Q

What will the results be if someone has hypomagnesaemia?

A
  • Low total calcium
  • Low ionised calcium
  • Variable phosphate
  • Low or normal PTH
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14
Q

What is the treatment of mild hypocalcaemia? (also what counts as mild?)

A

(asymptomatic, >1.9mmol/L)

  • Commence oral calcium tablets
  • If post thyroidectomy repeat calcium 24 hours later
  • If vitamin D deficient, start vitamin D
  • If low Mg2+, stop any precipitating drug and replace Mg2+
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15
Q

What is the treatment of severe hypocalcaemia?

A

(symptomatic or <1.9mmol/L)

  • This is a medical emergency
  • Administer IV calcium gluconate
  • Initial bolus (10-20 ml 10% calcium gluconate in 50-100ml of 5% dextrose IV over 10 minutes with ECG monitoring)
  • Calcium gluconate infusion
  • Treat the underlying cause
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16
Q

What are the parathyroid mediated causes of hypercalcaemia?

A

□ Primary hyperparathyroidism (sporadic)
□ Inherited variants
® Multiple endocrine neoplasia (MEN) syndromes
® Familial isolated hyperparathyroidism
® Hyperparathyroidism- jaw tumour syndrome
□ Familial hypocalciuric hypercalcemia
□ Tertiary hyperparathyroidism (renal failure)

17
Q

What are the non-parathyroid mediated causes of hypercalcaemia?

A

□ Hypercalcaemia of malignancy
® PTHrp
® Activation of extrarenal 1 alpha-hydroxylase (increased calcitriol)
® Osteolytic bone metastases and local cytokines
□ Vitamin D intoxication
□ Chronic granulomatous disorders
® Sarcoid, TB, Berylliosis, Histoplasmosis, Wegener’s

18
Q

What medications cause hypercalcaemia?

A 
□ Thiazide diuretics
□ Lithium
□ Teriparatide
□ Excessive vitamin A
□ Theophylline toxicity
19
Q

What are the miscellaneous causes of hypercalcaemia?

A 
□ Hyperthyroidism
□ Acromegaly
□ Pheochromocytoma
□ Adrenal insufficiency  
□ Immobilisation
□ Parenteral nutrition 
□ Milk alkali syndrome
20
Q

What are the main clinical features of hypercalcemia?

A
  • Renal: Polyuria, Polydipsia, Kidney stones
  • GI: Anorexia, constipation, nausea and vomiting
  • MSK: Muscle weakness
  • Neuro: decreased concentration
  • Cardiovascular: shortening of the QT intervals
21
Q

What investigations are done for hypercalcemia?

A
  • U&Es
  • Ca
  • PO4
  • Alk phos
  • Myeloma screen
  • Serum ACE
  • PTH
  • Consider ECG
22
Q

What is the treatment of hypercalcaemia?

A
  • Rehydration
    □ 0.9% Saline 4-6 litres over 24 hours
    □ Monitor for fluid overload
    □ Consider dialysis if severe renal failure
  • After rehydration, intravenous bisphosphonates
    □ Zoledronic acid 4mg over 15 mins
    □ Give more slowly and consider dose reduction if renal impairment
    □ Calcium will reach nadir at 2-4 days
23
Q

Explain primary hyperparathyroidism

A
  • Most patients are asymptomatic at diagnosis
  • Most cases are sporadic but has been associated with neck irradiation or prolonged lithium use
  • 85% parathyroid adenoma
  • 15% four gland hyperplasia
  • <1% MEN type 1 or 2A
  • <1% parathyroid carcinoma
  • Often present for years prior to diagnosis
24
Q

What are the investigations for hyperparathyroidism?

A 
○ Ca, PTH
○ U&amp;Es: check renal function
○ Abdominal imaging: renal calculi
○ DEXA: osteoporosis
○ 24 hour urine collection for calcium: Excl. FHH
○ Vitamin D
○ Parathyroid ultrasound 
○ SESTAMIBI
25
Q

What are the treatment options for hyperparathyroidism?

A

○ Parathyroid surgery
○ Medical management
- Generous fluid intake
- Cinacalcet (acts as a calcimetic, i.e. mimics the effect of calcium on the calcium sensing receptor on Chief cells, this leads to a fall in PTH and subsequently calcium levels)

26
Q

What are the indications for parathyroid surgery?

A
  • Presence of symptoms due to hypercalcaemia
  • Serum calcium: >0.25 mmol/L above the upper limit of normal
  • Osteoporosis on DEXA OR vertebral
  • Renal: eGFR< 60 or presence of kidney stones
  • < 50 year old
27
Q

What is familial hypocalciuric hypercalcaemia?

A
  • Autosomal dominant disorder of the calcium sensing receptor
  • Benign, no therapy indicated
  • Positive family history, screen young family members for diagnosis.
  • PTH may be normal or slightly elevated
  • No evidence of abnormal parathyroid tissue on ultrasound or isotope scan
28
Q

What is MEN type 1?

A
  • Primary hyperparathyroidism
  • Pancreatic
  • Pituitary
    ○ >95% of MEN 1 will have hyperparathyroidism
    ○ MENIN mutation (Chromosome 11)
    ○ 2-4% of cases of PHP may be MEN 1
    ○ Usually presents in the 2nd to 4th decade of life
    ○ Multi-gland involvement, High Recurrence Risk
29
Q

What is MEN type 2A?

A
  • Medullary thyroid cancer
  • Pheochromocytoma
  • Primary hyperparathyroidism
    ○ RET mutation
    ○ 20-30 % of MEN2A have hyperparathyroidism
    ○ Usually milder disease than in MEN 1
30
Q

What does MEN stand for?

A

Multiple endocrine neoplasia

endocrine (20 decks)

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