Parathyroid Flashcards
When is PTH normally secreted
In response to low serum ionised calcium levels
What is PTH secreted by
4 parathyroid glands that sit in the posterior of the thyroid gland
How does PTH act
It increases osteoclasts activity releasing Ca2+ and PO43- from bones
Inc ca2+ and dec PO43- resorption from the kidneys
Active 1,25-dihydroxyvitD3 production is increased
Overall to try to inc calcium and dec phosphate ]
Presentation of hyperparathyroidsim
Moans - depressed mood, tired, weak
Bones - pain, fracture, osteopenia, osteoporosis
Stones - renal stones - dehydrated but polyuric
Groans - abdominal pain, pancreatitis, ulcers
High bp
Causes of hyperparathyrodism
Solitary adenoma
Hyperplasia of all glands
Parathyroid cancer
Tests performed in suspected hyperparathyroidism
Blood - inc Ca2+ z and inc PTH (or inappropriately normal)
Dec PO43-
Inc ALP from inc osteoclasts activity
Imaging: osteitis fibrosa cystica - subperiosteal erosion, cysts, brown tumours of phalanges +/- acro-oestolysis +/- pepper pot skull
DEXA - osteoporosis/penia
Mx of primary hyperparathyroidism
Conservative if mild - ensure to drink plenty try to dec calcium and vit d level
Medical - calcimimemtics - which inc the sensitivity of parathyroid cells to Ca2+ therefore dec PTH secretion
Surg - removal of parathyroid one adenoma or all if hyperplastic
Complications of parathyroidectomy surgery
Hypoparathyroidism
Recurrent laryngeal nerve damage - hoarse voice
What are the causes of secondary hyperparathyroidism
Dec vit d intake
Chronic renal failure
What is the biochemical profile of secondary hyperparathyroidism
Dec Ca2+
Inc PTH which is appropriate due to the low ca2+
These results are linked to the lack of vitamin d or the inability to convert it at the kidneys due to CKD
What is the cause of tertiary hyperparathyroidism
Occurs after prolonged secondary hyperparathyroidism causing the gland to act autonomously having undergone hyperplastic or adenomatous change Seen in chronic kidney disease
Biochemical profile of tertiary hyperparathyroidism
Inc ca2+ and v.v. High PTH
Which is inappropriate as it has begun to undergo autonomous change
So s secreting more PTH than it should causing unlimited feedback control inc calcium
What is malignant hyperparathyroidism
Parathyroid related protein (PTHrP) is produced in some squamous cell lung cancers , breast cancer, and renal cell carcinoma
Mimics
PTH resulting in an inc ca2+
What is the cause of primary hypoparathyroidism
Gland failure leading to dec PTH secretion
What are the biochemical tests for primary hypoparathyroidism
Low ca2+
Inc PO43- Or normal
Normal ALP
