Week 1 - C - Biochemistry (2) - Hyperparathyroidism (Primary, secondary, tertiary), Renal Osteodystrophy, Paget's disease of bone Flashcards
Hyperparathyroidism involves overactivity of the parathyroid glands with high levels of parathyroid hormone (PTH). What is primary secondary and tertiary hyperparathyroidism?
* Primary hyperparathyroidism is a disorder of one or more of the parathyroid glands. The parathyroid gland(s) becomes overactive and secretes excess amounts of parathyroid hormone (PTH)
* Secondary hyperparathyroidism - physiological overproduction of PTH secondary to hypocalcaemia usually caused by vit D deficiency or CKD
* Tertirary hyperparathyroidism - seen in patients with chronic secondary hyperparathyroidism who develop an adenoma which will continue to produce PTH despite biochemical calcium correction
What are the different causes of primary hyperparathyroidism? What would the biochemical tests show?
Parathyroid gland
* Adenomas
* Hyperplasia
* Carcinoma - rare
Biochemical test results:
- High serum PTH and calcium and alk phosphatase
- Phosphate is normal or low
What would the biochemical tests show in secondary hyperparathyroidism?
Calcium would be decreased or normal PTH increased Vitamin D decreased Phosphate - could go either way
What would the biochemical tests show in tertiary hyperparathyroidism?
Increased calcium
Increased PTH
Decreased vit D
Increased phosphate
What are the symptoms of hyperparathyroidism? (primary)
Symptoms would be reflective of the high calcium levels
Painful bones
Abdominal groans - GI ulcers and pancreatitis
Renal stones
Psychic moans - depression
Thirst, nausea, polyuria
Hyperparathyroidism can result in fragility fractures and can also cause lytic lesions in bone What is a lytic lesion? What are these lytic lesions in bone known as?
Lytic lesions are an area in which the bone appears to have been eaten away leaving a clear area
Lytic lesions due to excess osteoclast activity eg in hyperparathyroidism are known as Brown’s tumours (aka osteitis fibrosis cystica)
What is the treatment of primary hyperparathyroidism? What is the emergency treatment of very high serum calcium levels?
Treatment of primary hyperparathyroidism is either surgery or nothing - ie surgery to remove the gland or do nothing, drink more fluids
Emergency treatment of very high serum caclium levels - IV fluids, biphosphonates and calcitonin
What is renal osteodystophy?
Renal osteodystrophy describes the typical bone changes due to chronic kidney diseases
Reduced phosphate excretion and inactive activation of vitamin D results in secondary hyperparathyroidism
What does the secondary hyperparathyroidism lead to from renal osteodystrophy?
Leads to subsequent osteomalacia, sclerosis of bone and calcification of soft tissues.
What is Paget’s disease of the bone?
Paget’s disease of the bone is a chronic bone disorder resulting in thickened, brittle and mishsapen bones
What happens in paget’s disease of the bone to cause the thickened, brittle and misshapen bone?
* In Paget’s disease, there is increased osteoclast activity resulting in increased bone turnover.
* The osteoblasts become more active to try to correct the excessive bone resorption
. * The osteoblasts form new bone however the new bone fails to remodel sufficiently
* This results in bone with increased thickness however it is brittle, misshapen and can fracture easily
Which bones are commonly affected in paget’s disease of the bone?
Bones commonly affected include the pelvis, femur, skull, tibia and sometimes the ear ossicles (resting in conductive deafness)
What are the presenting features of Paget’s disease of the bone?
Deep boring pain, and bony deformity and enlargement
Hearing loss due to ear ossicle involvement
Can also cause arhtitis if close to the join and high output cardiac failure (due to increased blood flow through pagetic bone)
What is raised in the blood in Paget’s disease of the bone?
Blood chemistry - normal calcium and phosphorus normally however serum alkaline phosphate is raised
What is a potential complication of Paget’s disease of the bone that should be suspected if sudden onset of worsening of bone pain?
Osteosarcoma formation
What is seen radiologically in Paget’s disease? What is the deformity that is seen on the tibia known as?
Radiographic features demonstrate that the affected bone is enlarged with thickened cortices and coarse, thickened trabeculae with mixed areas of lysis and sclerosis
Deformity known as the ‘sabre tibia’ can often be seen ;- curved tibia
What do bone scans show in paget’s? What bone scan would be carried out?
Bone scan’s demonstrate hot spots (increased uptake) in areas of affected bone - typically it is a Technetium 99m bone scan that is carried out
