Biochemistry Flashcards
What does increased PTH do to bones?
Increase resorption of bone.
What does increased PTH do to kidneys?
Increases calcium reabsorption.
What does increased PTH do to the intestines?
Increases GI calcium absorption.
What three things can cause primary hyperparathyroidism?
Benign adenoma, hyperplasia or rarely a malignant neoplasm.
What does overproduction of PTH cause?
Hypercalcaemia.
What are the signs and symptoms of hypercalcaemia?
Fatigue, depression, bone pain, myalgia, nausea, thirst, polyuria, renal stones, osteoporosis.
What serum results can we expect in hyperparathyroidism?
PTH elevated, high calcium and normal to low phosphate.
What is secondary hyperparathyroidism?
Physiological overproduction of PTH secondary to hypocalcaemia caused by vitamin D deficiency or CKD.
What is tertiary hyperparathyroidism?
Patients wit chronic secondary hyperparathyroidism who develop an adenoma and continue to make PTH despite chemical correction.
What can hyperparathyroidism cause in bones?
Fragility fractures or lytic lesions.
What are two other names for lytic lesions in bone?
Browns tumours or osteitis fibrosa cystica.
What treatment might lytic bone lesions require?
Skeletal stabilisation.
What hormone is made in high levels in hyperparathyroidism?
Parathyroid hormone.
What are the treatments for hyperparathyroidism?
Removal of adenomatous gland or treatment of underlying cause e.g. Vitamin D supplement. Hypercalcaemia needs emergency treatment e.g. Bisphosponates, IV fluids and calcitonin.
What condition results in renal dystrophy?
Chronic kidney disease.
What are the changes we see in renal dystrophy?
Reduced phosphate excretion and inactive activation of vitamin D.
What do the changes see in renal dystrophy result in?
Secondary hyperparathyroidism leading to osteomalacia, bone sclerosis and calcification of soft tissues.
What does pagets disease cause?
Thickened, brittle and mis-shapen bones.
How many bones does Pagets normally effects and what ones are they?
Only one or a few bones typically. Bones commonly include: the pelvis, femur, skull, tibia and sometimes the ear ossicles.
What happens if Pagets affects the ear ossicles?
Conductive deafness.
What are the possible causes of Pagets?
Genetic or viral (paramyxoviruses)
What happens to osteoclasts in Pagets?
Activity increases resulting in increased bone turnover.
What happens to osteoblasts in Pagets?
They become more active to try and correct excessive bone resorption. The new bone fails to remodel properly and results in increased bone thickness and brittleness.
What can Pagets cause?
It can be asymptomatic, cause arthritis if it near the joint, pathological fractures, deformity, pain and high output cardiac failure (due to increased output through pagetic bone).
What serum results would we expect in Pagets?
Raised alkaline phosphatase with calcium and phosphate usually being normal.
What radiological features do we see in Pagets?
Enlarged bone with thickened cortices and coarse thickened trabeculae with mixed areas of lysis and sclerosis. Bone scans show marked increased uptake in the affected bone.
What is the treatment for Pagets?
Bisphosponates to inhibit osteoclasts.
Calcitonin if there is extensive lysis.
Joint replacement
Stabilisation of pathological femoral fractures with long intramedullary nails or plates.
