Parathyroid Disease Flashcards
What is the brief physiology of Parathyroid Hormone (PTH)?
- PTH secreted by parathyroid glands
- In response to low ionised Ca levels
- Controlled by negative feedback via Ca levels
- PTH acts by
- ↑ osteoclast activity releasing Ca and PO4 from bones
- ↑ Ca and ↓ PO4 absorption in kidney
- ↑ Active Vit D3 production (thus ↑ Ca and ↓ PO4)
Primary hyperparathyroidism is typically seen in elderly females w/ an unquenchable thirst and inappropriately normal or raised PTH level.
What are causes of primary hyperparathyroidism?
- Solitary adenoma (80%)
- Parathyroid hyperplasia (15%)
- Multiple adenoma (4%)
- Carcinoma (<1%)
What is the clinical presentation of 1o hyperparathyroidism?
- Often asymptomatic w/ ↑Ca on routine tests
- Hypercalcaemia → ‘bones, stones, abdo groans + psychic moans’
- Weak, tired, thirsty, dehydrated but polyuric, renal stones, abdo pain
- Bone resorption → can cause pain, fractures + osteopenia/osteoporosis
- Hypertension
Which investigations for 1o hyperparathyroidism?
- Vitals → HTN
- Bloods → raised Ca and low PO4 (unless in renal failure)
- PTH raised or normal
- Increase ALP from bone activity
- Bone scans → pepperpot skull / osteitis fibrosa cystica (due to resorption)
- Technetium-MBI substraction scan → nuclear imaging scan of parathyroids
What is the conservative management for 1o hyperparathyroidism?
- May be offered if Ca <0.25 mmol/L above the upper limit of normal AND the patient is >50 yrs AND there is no evidence of end-organ damage
- High fluid intake to prevent stones and avoid thiazides*
*Thiazides increase calcium resorption from kidney whereas loop diuretics increase excretion of calcium
What is the definitive management for 1o hyperparathyroidism?
Total parathyroidectomy
What are blood test results in 2o hyperparathyroidism?
- Low (or normal) calcium
- Increased PTH
- Increased phosphate
What are causes of 2o hyperparathyroidism?
- Low vit D intake
- Chronic renal failure → parathyroid hyperplasia occurs as a result of low Ca, almost always in setting of chonic renal failure
Treat by medically correcting underlying causes
What are the blood results for 3o hyperparathyroidism?
- Increased calcium
- Very high PTH (inappropriately)
Why does 3o hyperparathyroidism occur?
- Occurs after prolonged 2o hyperparathyroidism
- Causes glands to act autonomously having undergone hyperplastic changes
- Seen in chronic renal failure
In primary hypoparathyroidism, PTH secretion is decreased due to gland failure.
What will blood results show?
- Low calcium
- High phosphate
- Normal ALP
Primary hypoparathyroidism presents with signs of hypocalcaemia.
What are the causes of 1o hypoparathyroidism?
- Autoimmune
- Congenital (DiGeorge syndrome)
What is the treatment of 1o hypoparathyroidism?
- Ca supplements + calcitriol
What is pseudohypoparathyroidism?
- Failure of target cell response to PTH
- Sx → short metacarpals / round face / short stature / low IQ
What are causes of secondary hypoparathyroidism?
- Radiation
- Surgery (thyroidectomy etc)
- Hypomagnesaemia (Mg required for PTH secretion)
