Week 218 - Fractured Hip Flashcards
Week 218
What does bone “do”?
– Provide structural support for the body
– Protect vital organs
– Act as a home for bone marrow
– Provide a reservoir for minerals (eg calcium)
Week 218
NEED TO GO OVER BONE BIOLOGY, ROLE OF VIT D and its SUBSTITUTES, HOW DEPOSITION IS CAUSED, ROLE OF PTH ETC
to do
Week 218
What is an Osteoclast, and what is its role?
An Osteoclast is a type of bone cell theat resorbs bone tissue.
Osteoclasts are regulated by several hormones, including** parathyroid hormone** (PTH) from the parathyroid gland, calcitonin from the thyroid gland, and growth factor interleukin 6 (IL-6). This last hormone, IL-6, is one of the factors in the disease osteoporosis, which is an imbalance between bone resorption and bone formation.
Week 218
What is the role of Parathyroid Hormone (PTH) in bone remodelling?
PTH enhances the release of calcium from the large reservoir contained in the bones.Bone resorption is the normal destruction of bone by osteoclasts, which are indirectly stimulated by PTH.
PTH also enhances active reabsorption of calcium and magnesium from distal tubules and the thick ascending limb or the kidney, and absorbtion of Calcium from the Small Intestine.
Week 218
What is the role of Calcitonin in bone remodelling?
Calcitonin acts to reduce blood calcium (Ca2+), opposing the effects of parathyroid hormone (PTH).
Specific effects in bone:
- *Inhibits osteoclast** activity in bones.
- *Stimulates osteoblastic** activity in bones.
Week 218
In very basic terms - what is the difference between Trabecular and Cortical bone?
Trabecular bone is the “Scaffolding”, and Cortical bone is the “Cover”.
Week 218
Define Osteoporosis.
“Systemic skeletal disease characterized by low bone mass and microarchitectural deterioration of bone tissue, leading to enhanced bone fragility and a consequent increase in fracture risk”
Week 218
Deficiency of which sex hormone is a risk factor for Osteoporosis?
Oestrogen.
Week 218
How is Osteoporosis usually diagnosed?
Osteoporosis is usually diagnosed with a DEXA Scan (Dual Energy X-Ray Absorpitometry).
The diagnosis is based on a measurement of Bone Mass Density (BMD) in g/cm2.
Week 218
With reagrds to the measurement of Bone Mass Density in Osteoporosis, what is meant by the “Z” score?
#standard deviations from age and gender-matched mean
Week 218
With regards to the measurement of Bone Mass Density in Osteoporosis, what is meant by the “T” score?
#standard deviations from gendermatched young adult mean
Week 218
With regards to the measurement of Bone Mass Density in Osteoporosis, what is the classification of disease, with relation to the T score?
0 to -1 = normal
- *-1 to -2.5 = osteopenia**
- 2.5 below = osteoporosis
- 2.5 and below with fracture = severe osteoporosis
Week 218
Name two drugs that increase bone formation.
– Teriparatide
– Strontium Ranelate
Week 218
Name two drugs that decrease bone resorption.
- Bisphoshonates
– RANK Ligand inhibitors (Denosumab)
Week 218
Name some Biphosponates, and state what effect they have.
– Alendronic acid, Risedronate, zolendronic acid, ibandronate
– Inhibit osteoclasts
Week 218
What type of drug is Denosumab? What does it do?
Denosumab is a RANK Ligand inhibitor
Prevents osteoclast differentiation, activation and survival
– ‘Biological’ drug – humanised antibody
– Subcutaneous injection every 6 months
– Side effects
Rarely ONJ, atypical fracture
– Often given with calcium and vitamin D supplement
Week 218
What is Teriparatide, and how does it work?
This is a Recombinant human parathyroid hormone
• Normally PTH causes bone loss
• BUT given in pulses
– Increases bone production (anabolic)
– Increases BMD
Week 218
What is the common term given to the condition Osteomalacia?
Rickets
Week 218
What are the actions of Vitamin D?
– Maintain calcium homeostasis
– Maintain bone health
– Increase Ca2+ from the gut
– Increase phosphate absorption from gut
– Osteoclast function / maturation
Week 218
What is the effect of a Vitamin D Deficiency on bone density?
Low Vitamin D leads to reduced Calcium absorption from the gut. This in turn leads to low Serum Calcium, and a subsequent increase in the release of PTH from the parathyroid glands. PTH causes Calcium resorption from bone, which in turn reduces bone mineralisation (creates “sort bones”).
Week 218
Name some causes of Vitamin D Deficiency.
- Inadequate sunglight
- Inadequate diet
- Malabsorbtion
- Medication
- Abnormal metabolism of vit D (Renal or Hepatic disease)
- Hypophosphataemia
- 1-alpha hydroxylase deficiency (rare)
- congenital vitamin d resistance (rare)
Week 218
What is Rickets?
Rickets is a condition that affects bone development in children. It causes the bones to become soft and weak, which can lead to bone deformities.
Week 218
What is Osteomalacia? What are the clinical signs of this disease?
Osteomalacia is the softening of the bones caused by defective bone mineralization secondary to inadequate amounts of available** phosphorus and calcium**, or because of overactive resorption of calcium from the bone as a result of hyperparathyroidism (which causes hypercalcemia, in contrast to other aetiologies). Osteomalacia in children is known as rickets.
Week 218
In a Vitamin D deficient patient, what would you expect from the following tests:
- Serum 25(OH) Vitamin D
- Serum PTH
- Serum calcium
- Serum phosphate
- Alkaline phosphatase
Serum 25(OH) Vitamin D - LOW
Serum PTH - INCREASED
Serum calcium - LOW/NORMAL
Serum phosphate - LOW
Alkaline phosphatase - INCREASED
Week 218
What is Pagets Disease?
Paget disease of bone is a chronic disorder that can result in enlarged and misshapen bones. Paget’s is caused by the excessive breakdown and formation of bone, followed by disorganized bone remodelling. This causes affected bone to weaken, resulting in pain, misshapen bones, fractures and arthritis in the joints near the affected bones.
Week 218
What is the first manifestation of Pagets disease?
The first manifestation of Paget’s disease is usually an elevated alkaline phosphatase in the blood. Overall, the most common symptom is bone pain.
Week 218
What is the difference between Monostotic or Polyostotic Pagets disease?
Monostotic - affects one bone
Polyostotic - Affects many bones
Week 218
Which clinical (blood/urine) results would be definitive of Pagets Disease?
_ Blood tests_
• High alkaline phosphatase (NB. liver disease)
• Normal calcium, vitamin D, PTH, phosphate
– Urinary hydroxyproline increased
– Isotope bone scan – increase uptake
Week 218
Which class of drug is used to treat Pagets disease? Can you give any examples?
Bisphosphonates.
Examples:
Risedronate
Zolendronate
Week 218
Which conditions are indicated by the following sets of results?
This is VERY likely to be an EMQ type question. Learn it.
Week 218
What effect does a decrease in plasma calcium have on plasma CaHPO4 absorption?
Plasma CaHPO4 absorption increases when there is a decrease in plasma Calcium.
Week 218
UV light converts 7- dehydrocholesterol to ______.
Cholecalciferol
Week 218
Cholecalciferol is converted in the liver to _______
25- Cholecalciferol
Week 218
Without the effect of PTH, what is 25-cholecalciferol converted to in the Kidneys?
24,25 D variants.
Week 218
In the presence of PTH, what is 25-Cholecalciferol converted to in the kidneys?
Calcitriol.
Week 218
What is the hormonal response to hypophosphataemia?
Increased Calcitriol, leading to decreased PTH, leading to a decrease in bone calcium resorption, an increase in intestinal phosphate absorption, and a decrease in phosphate excretion from the urine.
Week 218
Which disease is related to a problem with bone density and strength?
Osteoporosis.
Week 218
Which disease is related to a problem with bone mineralisation?
Osteomalacia
Week 218
Which disease is related to a disorder of bone formation?
Pagets
Week 218
What is the Berg balance scale?
A Formal assessment of balance, often used in the provision of elderly care.
Week 218
What is the “TUG” test?
This is the “timed get up and go” test. It’s used when assessing an elderly patients ability to mobilise.
Week 218
Which blood measurement is taken as the level of Vitamin D in the body?
25-OHD
Week 218
A patient on the ward has some blood tests done. Their 25-OHD (Vitamin D levels) are 80nmol/l. Is this an acceptable level? What does it show?
Anything over 75 nmol/L shows their on bloody good form. This patient is HEALTHY!
Week 218
A patient on the ward has some blood tests done. Their 25-OHD (Vitamin D levels) are 48 nmol/l. Is this an acceptable level? What does it show?
Anything under 50nmol/L indicates that Vitamin D supplementation is needed.
(They also probably need to stop staring at computer screens in the library revising, and actually go outside where this is thing called the SUN.)
Week 218
A patient on the ward has some blood tests done. Their 25-OHD (Vitamin D levels) are 23 nmol/l. Is this an acceptable level? What does it show?
This is not good.
< 25nmol/l means that Calciferol is indicated (high risk of rickets and osteomalacia).
Daily recommendations of 400IU(10g) per day only sufficient to prevent rickets.
Week 218
According to Saunders et al., most hip fractures of the elderly occur where?
In care homes.
Week 218
Bone density is a ____ indicator of fractures in individuals.
Bone density is a **poor **indicator of fractures in individuals.
Week 218
The DIPART trial looked at what?
Vitamin D consumption in individuals.
Week 218
Is poor vidual acuity a risk factor for falls?
YES. There is a large body of evidence to support this.
Week 218
What is the Hayflick limit?
The Hayflick limit (or Hayflick phenomenon) is the number of times a normal human cell population will divide until cell division stops. Empirical evidence shows that the telomeres associated with each cell’s DNA will get slightly shorter with each new cell division until they shorten to a critical length.