Parathyroidism Flashcards
What 3 things have an effect on calcium balance in the body?
What of them causes an increase and what causes a decrease?
Increase
- PTH
- Vit D (calcitriol)
Decrease
- calcitonin
What is the name of the G-coupled receptor found on parathyroid cells that helps to regulate calcium levels?
What is the name of the cell which this is found on?
Calcium-sensing receptor
Chief cells (in parathyroid) -> produce PTH
What 3 ways does PTH work to increase extracellular calcium levels?
Bone
- Increased bone breakdown (by increasing number of osteoclasts)
Gut
- Vit D activation -> Ca2+ absorption in gut
Renal
- Increase in phosphaturia (phosphate in urine)
- Increase Ca2+ absorption from urine
- Activates Vit D into calcitriol
What is the typical presentation of hypercalceamia?
Bones (boney pain + muscle weakness)
Stones (kidney stones)
Abdominal groans (constipation)
Psychic moans (depression + confusion)
(+thrones - polyuria)
Name 3 complications of hyperparathyroidism
Osteoporosis
Renal stones
Bone disease - “brown tumours”
Describe the differences in levels of PTH and serum calcium in primary, secondary and tertiary hyperparathyroidism
All high PTH
Primary - high Ca2+
Secondary - low Ca2+
Tertiary - normal/high Ca2+
If a patient presents with high PTH and ALP. What should be screened for?
Bone malignancy - isotope bone scan
What genetic condition is associated with hyperparathyroidism?
MEN
What is the difference in causes between primary, secondary and teritary hyperparathyroidism?
Primary - caused by commonly parathyroid adenoma NOT hyperplasia
Secondary - caused commonly by chronic renal disease/vit D deficiency
Tertiary - caused by years of CKD -> PTH released independent of calcium levels
Explain in detail how secondary/tertiary hyperparathyroidism works
CKD
- leads to reduced phosphate being excreted in urine -> increase phosphate in blood -> increased phosphate binding to calcium -> less avaliable calcium
- leads to decreased calcium reabsorption
Vit D deficency -> reduced calcitriol -> reduced gut Ca2+ reabsorption
What kind of hyperparathyroidism also presents with osmotic symptoms?
Primary
How is hyperparathyroidism diagnosed?
What single test can be used to diagnose primary?
Blood tests
Calcium urine levels will be high
How is primary hyperparathyroidism managed?
Surgery
How is secondary hyperparathyroidism managed?
Renal transplant
Bisphosphonates
? Vit D analogue
What is the MoA of bisphosphonates?
Prevent osteoclast action -> protect bone from osteoporosis
also reduce Ca2+ levels - used in secondary for bone protection
How is acute hypercalcaemia managed?
Fluids
Biphosphonates
What is the differnce in the phosphate serum levels in primary and secondary hyperparathyroidism?
Primary - low phosphate
Secondary - high phosphate (think phosphate binds to calcium)
When is surgery indicated in primary hyperparathyroidism?
If causing complications
What ECG abnormalities can be seen in hypocalcaemia?
Prolonged QT
What are two clinical signs of hypocalcemia?
Chvostek’s sign
- when tap anterior to ear -> face twinges
Trousseau’s sign
- BP cuff occludes brachial artery
- hand and wrist flex
(trousseau is a type of cloth used in wedding dresses - imagine someone asking to marry you and they have your hand and hand and wrist flex away)
What is the most common cause of hypoparathyroidism?
Post-operative removal
What are the calcium levels like in hypoparathyroidism?
Low
How is hypoparathyroidism managed?
Supplements
- Vit D
- Ca2+
What genetic disorder is associated with absence of parathyroid?
DiGeorge syndrome
What are the symptoms of hypocalcaemia?
- Parasthetisa of distal digits and lips
- tetany (involuntary contraction) of muscles
- muscle weakness
- seizures
- prolonged QT
How is acute hypocalcaemia (<2) managed?
Why is it an emergency?
EMERGENCY
- IV calcium gluconate
Low calcium can lead to cardiac arrhythmias and tetany of muscles inc. those in resp. pathway -> resp distress
What other electrolyte should be tested for in a patient with low Ca2+?
Mg
Ca2+ release from cells is dependant on Mg
Low Mg = low Ca2+ release
If someone has low Ca2+ due to low Mg+ how should they be managed?
Replace both magnesium and calcium
A patient presenting from mild hypocalcaemia (>2) how should they initially be managed following parathyroidetomy?
Observe - very common following initial surgery
What is the more common cause of primary hyperparathyroidism. Parathyroid adenoma or hyperplasia?
Adenoma
