Nutritional, metabolic and endocrine diseases of bone

Question 1

List the nutritional, metabolic and endocrine diseases of bone

Answer 1

• Osteomalacia
• Rickets
• Hyperparathyroidism
• Osteoporosis
• Acromegaly
• Infantile hypothyroidism
• Cushing’s disease

Question 2

What is osteomalacia?

Answer 2

• 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

Question 3

What is rickets?

Answer 3

• osteomalacia in growing child
• low vitamin D, Ca, or phosphate
• collagen matrix normal
• inadequate mineralisation

Question 4

What are the causes of primary hyperparathyroidism?

Answer 4

Parathyroid:
• adenoma
• hyperplasia
• carcinoma

Non-parathyroid tumour secreting parathyroid-like substance

Multiple endocrine neoplasia type II
• medullary carcinoma of thyroid
• pheochromocytoma
• Cushing’s syndrome

Question 5

What are the causes of secondary hyperparathyroidism?

Answer 5

Response of gland to chronic hypocalcaemia (usually renal glomerular disease) by negative feedback regulatory mechanism

Question 6

What are the causes of tertiary hyperparathyroidism?

Answer 6

Escape of the gland from the regulatory effects of serum calcium levels in patients following prolonged stimulation, such as renal haemodialysis

Question 7

What are the clinical features of hyperparathyroidism?

Answer 7

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

Question 8

What is the aetiology of primary osteoporosis?

Answer 8

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

Question 9

What is the aetiology of secondary osteoporosis?

Answer 9

• 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

Question 10

List the different types of osteoporosis?

Answer 10

• primary
• secondary
• generalized
• regional

Question 11

When does bone mass peak?

Answer 11

• peaks at 35

* loss of 0.3-0.5% per year after that

Question 12

What are the clinical features of osteoporosis?

Answer 12

• asymptomatic unless fracture
• fracture in hip, distal radius, vertebral below T8

Frature causes:
• pain (gone in 3 months)
• deformity (reduced height, hyperkyphosis)

Question 13

What investigations do we do for osteoporosis?

Answer 13

• X-ray shows decreased density, wedge and crush fractures
• DEXA scan
• T score
• quantitative calcanea ultrasonography

Question 14

What is a DEXA scan?

Answer 14

• Dual Emission X-ray absorption scan
• low radiation
• result in SD (standard deviation), difference from normal score
• gives a T score

Question 15

What is a T score? what is a Z score?

Answer 15

• 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

Question 16

What is a T score for normal, osteopenia and osteoporosis?

Answer 16

Normal: 0 to -1.0
Osteopoenia: -1 to -2.5
Osteoporosis: < -2.5

Question 17

What is acromegaly? how does it link to bone and cartilage?

Answer 17

• 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

Question 18

What is infantile hypothyroidism? how does it link to bone and cartilage?

Answer 18

• 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

Question 19

What is Cushing’s disease? how does it link to bone and cartilage?

Answer 19

• 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

Question 20

What is hyperparathyroidism? (definition, list types, demographics)

Answer 20

• increased circulating parathyroid hormone (PTH)
• primary, secondary or tertiary
• > 40
• women > men

Question 21

What is the definition of osteoporosis?

Answer 21

• 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

Question 22

What are the clinical features of rickets?

Answer 22

• 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