Chemical Pathology Flashcards
Role of calcium, why it needs to be fixed?
nerves, muscles rely on this for depolarisation
Hypercalcaemia -> failure of depolarisation – stones, bones, groans, moans + nephrogenic DI
o Hypocalcaemia -> “trigger happy CNS” – epilepsy (aberrant firing of nerves and muscles) – CATS go numb
How does it travel in blood?
free and ionised - fixed level
albumin bound
complex with citrate/phosphate
What is corrected calcium ?
If album is low (sepsis) will affect free calcium - may appear higher
What does PTH do?
Released from PTH gland (detects ca2+ levels)
- activates 1 alpha hydroxylase (VIT D SYNTH)
- osteoclast activation
- resorption calcium from kidney
- excrete phosphate from kidney
Where is vitamin D synthesised? It’s role
hydroxylysed in liver at 25, then activated in kidney at 1 by 1 alpha hydroxlyase.
Cholecalciferol to Calcitriol
Intestinal Ca2+ absorption and intestinal phosphate absorption
o Critical for bone formation (with osteoblasts)
What are some of the metabolic bone disorders? Risk factors and clinical features?
Osteoporosis, Osteomalacia, Paget’s Disease
due to lack of sunlight, dark skin, diet
osteomalacia - bone and muscle pain, increased risk fractures, looser zones
rickets - bow legs, costochondral swelling, myopathy
osteoporosis - loss of bone mass, but normal bone, normal calcium, asymptomatic until first symptom
Treatment fro osteoporosis?
Weight bearing exercise
§ Stop smoking
§ Reduce ETOH
o Drugs
§ Vitamin D/Ca
§ Bisphosphonates (alendronate) – decrease bone resorption – osteonecrosis of jaw
§ Teriparatide – PTH derivative – anabolic
§ Strontium – anabolic + anti-resorptive
§ Oestrogens – HRT
§ SERMs (oestrogen-like drug) – raloxifene (like Tamoxifen)
§ Denosumab – biologic anti-RANK-L antibody
What are the symptoms of Primary Hyperparathyroidism
parathyroid adenoma/carcinoma
hyperplasia due to MEN1
Malignancy
Increased Ca2+
increased or normal PTH
Increased urine calcium.
decreased phosphate
How does hypercalcaemia present in malignancy? what are other causes of non-PTH hypercalcaemia?
Humoral hypercalcaemia of Mal
Bony Mets
Haematological malignancy
sarcoidosis
thyrotoxicosis
hypoadrenalism
Treatment for hyper and hypocalcaemia
Fluids - 0.9% saline 1L/hr
Treat underlying cause
bisphosphonates in relation to Paget’s disease
