Nutritional, metabolic and endocrine diseases of bone Flashcards
List the nutritional, metabolic and endocrine diseases of bone
- Osteomalacia
- Rickets
- Hyperparathyroidism
- Osteoporosis
- Acromegaly
- Infantile hypothyroidism
- Cushing’s disease
What is osteomalacia?
- bone softening
- defective mineralization
- inadequate calcium and/or phosphorus
- low intestinal absorption Ca, tubular disorder, renal osteodystrophy, vitamin D deficiency
- collagen matrix NORMAL
- symptomless or bone pain, muscle weakness, pathological fractures, hypocalcaemia features
What is rickets?
- osteomalacia in growing child
- low vitamin D, Ca, or phosphate
- collagen matrix normal
- inadequate mineralisation
What are the causes of primary hyperparathyroidism?
Parathyroid:
• adenoma
• hyperplasia
• carcinoma
Non-parathyroid tumour secreting parathyroid-like substance
Multiple endocrine neoplasia type II
• medullary carcinoma of thyroid
• pheochromocytoma
• Cushing’s syndrome
What are the causes of secondary hyperparathyroidism?
Response of gland to chronic hypocalcaemia (usually renal glomerular disease) by negative feedback regulatory mechanism
What are the causes of tertiary hyperparathyroidism?
Escape of the gland from the regulatory effects of serum calcium levels in patients following prolonged stimulation, such as renal haemodialysis
What are the clinical features of hyperparathyroidism?
Hypercalcaemia causes: • weakness, muscle fatigue, hypotonicity • deposition of calcium: -renal medulla: tubular reabsorption of water impaired -polyuria, polydipsia -renal calculi -conjunctiva • anorexia, nausea, vomiting, dyspepsia, peptic ulceration, pancreatitis
Resporption from bone causes:
• bone pain, pathological fractures, deformity
• backache
• psychiatric, lethargy, coma, convulsions
What is the aetiology of primary osteoporosis?
Juvenile
Idiopathic: • Type I -postmenopausal -low osteoblast with high osteoclasts ->50, women x6 -Colles' fracture, distal radius -vertebral crush / wedge fractures • Type II -involutional/senile -ageing process -low osteoblast ->60, women x2 -femur, humerus, tibia, pelvis
What is the aetiology of secondary osteoporosis?
- genetic / congenital (Marfan’s)
- hypogonadal (anorexia nervosa)
- endocrine (diabetes mellitus)
- deficiency (calcium, magnesium, vitamin D, protein
- inflammatory (RA, SLE)
- Metastatic
- Drugs
- alcoholism, depression, immobility, multiple sclerosis
List the different types of osteoporosis?
- primary
- secondary
- generalized
- regional
When does bone mass peak?
- peaks at 35
* loss of 0.3-0.5% per year after that
What are the clinical features of osteoporosis?
- asymptomatic unless fracture
- fracture in hip, distal radius, vertebral below T8
Frature causes:
• pain (gone in 3 months)
• deformity (reduced height, hyperkyphosis)
What investigations do we do for osteoporosis?
- X-ray shows decreased density, wedge and crush fractures
- DEXA scan
- T score
- quantitative calcanea ultrasonography
What is a DEXA scan?
- Dual Emission X-ray absorption scan
- low radiation
- result in SD (standard deviation), difference from normal score
- gives a T score
What is a T score? what is a Z score?
• for bone density
T score:
• measures the difference between patient’s BMD and that of a healthy 30yr old of the same sex
• measured in SD
Z score: normally distributed, and allows comparisson among different nationalities and sexes
What is a T score for normal, osteopenia and osteoporosis?
Normal: 0 to -1.0
Osteopoenia: -1 to -2.5
Osteoporosis: < -2.5
What is acromegaly? how does it link to bone and cartilage?
- excessive secretion of hGH in adult
- from: adenoma of somatotropin cells, secreting excess hGH
- thick soft tissues
- periosteal ossification, thickening bones
- projecting jaw, hands, feet splayed
- leads to osteoarthritis
- pain due to nerve compression
- muscle wasting,
- high glucose, hypertension, hypertrophy of heart
- die from cardio problems
What is infantile hypothyroidism? how does it link to bone and cartilage?
- under activity of thyroid gland in kids
- Endemic: goitre due to iodine deficiency, appears in 3rd generation
- Sporadic: due to congenital hypoplasia of thyroid
- maybe normal at birth, abnormality appears within weeks
- irreversible unless treated early
- deterioration in school performance, games
- arrest or slow in growth
What is Cushing’s disease? how does it link to bone and cartilage?
- high glucocorticoids (corticosteroid)
- result of excess ACTH secreted from pituitary adenoma
- weight gain (lemon on toothpicks, moon face, buffalo hump)
- collagen breakdown (thin skin, bruising, striae, poor healing
- loss of protein from muscles, weakness
- bone weakening (osteoporosis, fractures, deformity)
- growth retardation
- hyperglycaemia (diabetes mellitus
- skin pigmentation (increased MSH)
- immune suppression
- hypertension
- facial hair, balding
What is hyperparathyroidism? (definition, list types, demographics)
- increased circulating parathyroid hormone (PTH)
- primary, secondary or tertiary
- > 40
- women > men
What is the definition of osteoporosis?
- insufficient formation or increased resorption of bone matrix
- decreased bone mass
- fully mineralized bone
- low quantity, normal quality
- generalized or localized
- primary or secondary
- common, 200 million worldwide
What are the clinical features of rickets?
- long bones especially
- cartilage thickened and irregular
- bone poorly calcified and scanty
- stunted growth
- bone pain, tenderness, distortion, fractures
- bowlegs, rachitic rosary, pigeon chest, asymmetrical skull, pelvis
- dental deformity, muscle cramps
- scoliosis, kyphosis
