Flashcards in Parathyroid: Science and Clinical Deck (50)
Main effect of parathyroid hormone
raise the blood calcium
What are the 3 main ways PTH raises blood calcium?
1. breaking down bone 2. increasing absorption of calcium from food 3. increasing the kidneys ability to hold onto calcium
7-dehydrocholesterol is converted by UV waves into ____________ or cholecalciferol
7-dehydrocholesterol is converted by UV waves into VITAMIN D3 or cholecalciferol
Where is cholecaliferol converted into calcidilol?
What is calcidilol?
Where is 25hydroxyVitaminD3 activated?
What is 25hydroxyVitamin D3 converted into in the kidney?
What is 1,25dihydroxyvitamin D3 also known as?
Calcitriol acts on the ____ of the kidney to increase calcium absorption
PCT - proximal convoluted tubule
Calcitriol actis on the gut to...
increase calcium and phosphate absorption
Calcitriol acts on the bone to...
increase resorption of calcium and phosphate
Calcitriol acts on the parathyroid gland...
in a negative feedback manner - inhibiting further PTH release
PTH acts on the ____ of the kidney to increase calcium reabsorption
DCT - distal convoluted tubule
PTH acts on the bone to...
activate the osteoblasts which subsequently activate the pre-osteoclasts
osteoclasts are a form of....
macrophage - they respond to macrophage colony stimulating factor
Action of calcitonin
released in response to raised plasma calcium and has opposite effects to PTH
Calcitonin is released from...
the parafollicular cells of the thyroid gland
the majority of cases of primary hyperparathyroidism are caused by...
a solitary adenoma
Symptoms which may be associated with primary hyperparathyroidism
weak, tired, thirsty, dehydrated, polyuria, renal stones, abdominal pain, pancreatitis, duodenal (less gastric) ulcers, fractures, osteoporosis or osteopaenia, increase BP
What genetic condition is primary hyperparathyroidism associated with?
What are the 3 Ps associated with MEN 1?
Parathyroid hyperplasia, Pancreatic endocrine tumours, Pituitary tumour
The MEN1 gene is a...
tumour suppressor gene
Investigations for primary hyperparathyroidism
raised Ca, raised or normal PTH, decreased phosphate, increased Alk Phos, 24 hr urinary Ca, DEXA, X-ray, CT
what should be avoided in primary hyperparathyroidism?
excess calcium and vitamin D intake, avoid thiazide diuretics
Surgery is always indicated with primary hyperparathyroidism - TRUE/FALSE
FALSE - surgery is only indicated if there is end-organ damage
Indications for surgery to treat hyperparathyroidism
bone disease, gastric ulcers, renal stones, osteoporosis, less than 50 years old, renal impairement (<60ml/min eGFR)
Drug that can be used in tertiary and carcinoma hyperparathyroidism
cinacalet - increases the PT to increased calcium thus reducing the production of PTH
Results from secondary hyperparathyroidism
decreased calcium and appropriately raised PTH
Causes of secondary hyperparathyroidism
decreased Vit D intake and chronic renal failure