bone and parathyroid disease Flashcards
what are osteoblasts
bone forming cells
what are osteoclasts
bone resorbing cells
what is the biologically active form of vitamin D
calcitriol
what is calcitonin produced by
parafollicular cells in the thyroid gland
what is osteoporosis
progressive systemic skeletal disease characterised by low bone mass and micro-architecture deterioration of bone tissue, with a consequent increase in bone fragility and susceptibility of fracture
osteoporosis cause
increase in bone turnover due to imbalance in bone turnover, leading to a shift towards increased resorption which induced bone mass and causes the micro-architectural changes
osteoporosis risk factors
- age
- family history
- anorexia
- myeloma
- rheumatoid arthritis
- liver/renal failure
- drugs (prolonged steroids)
- smoking, alcohol, immobility, low BMI
- hyperthyroidism, hyperparathyroidism, diabetes, hypogonadism, early menopause
- chronic liver disease, IBD, pancreatitis, malabsorptive conditions (coeliac)
osteoporosis presentation
- asymptomatic until minimal trauma fracture occurs
- common fractures are colles, hip and vertebral wedge
- domino effect of one fracture leading to increased change of anther
DEXA score > 1 =
good bone mineral density
DEXA score 1 to -1 =
normal bone mineral density
DEXA score -1 to -2.5 =
osteopenia
DEXA score < -2.5 =
osteoporosis
osteoporosis lifestyle management
smoking cessation, alcohol reduction, resistance training, calcium supplements, education about fall prevention (given to patients with osteoporosis and osteopenia)
osteoporosis pharmacological management
- bisphosphonates (prevent bone resoprtion by killing off osteoclasts)
- strontium ranelate (reduces bone resorption)
- teriparatide
- denosumab (monoclonal antibody against RANKL)
Paget’s disease pathophysiology
- metabolic disease of bone
- characterised by increased bone turnover associated with increased number of both osteoblasts and osteoclasts
- result is bone remodelling with resultant bone being deposited in a disorganised manner
- consequences of bone remodelling include bone enlargement and deformity due to disorganised bone being weaker
- primarily affects the tibia, femur, vertebrae, skull and pelvis
Paget’s presentation
- most are asymptomatic
- deep, boring bone pain that is worse at night and with weight bearing
Paget’s investigations
- bloods: high ALP, normal calcium, normal phosphate
x-ray
- early disease: lytic lesions
- late disease: cortical thickening, deformity
- skull disease: cotton wool appearance
what is Ricket’s
abnormal bone mineralisation during periods of active bone growth ad before fusion of epiphyseal plates
what is osteomalacia
abnormal bone mineralisation in the time after the fusion of the epiphyseal plates
osteomalacia/Rickets pathophysiology
abnormal bone mineralisation (normal amount of bone, but mineral content of this bone is low)
osteomalacia/Rickets causes
- vitamin D deficiency
- renal bone disease
- liver disease (cirrhosis)
- drugs (anti-convulsant)
Rickets presentation
- growth retardation
- bow legged or knock kneed
- hypotonia
- apathy
osteomalacia presentation
- bone pain
- fractures, especially femoral neck
- proximal myopathy
- waddling gait
osteomalacia/Rickets diagnosis
bloods: hypocalcaemia
- vitamin D deficiency: low calcium, PO4 and vitamin D, high ALP and PTH
- renal bone disease: low calcium, high PO4, PTH and ALP
x-ray
- looser zones, rugged metaphyseal plates, reduced cortical bone
- looser zones are characteristic (they are pseudo-fractures and are sclerotic lines that lie perpendicular to cortical bone)
- rugged metaphyseal plates are seen in rickets
osteomalacia/Rickets caused by vitamin D deficiency management
calcium/vitamin D supplements
osteomalacia/Rickets caused by renal disease management
diet restriction, phosphate binders, alfacalcidol (vitamin D)
primary hyperparathyroidism causes
- result of either solitary parathyroid gland adenoma or hyperplasia of all four parathyroid glands
- may present as part of MEN
primary hyperparathyroidism presentation
- hypertension
- bone resorption: bone pain, fractures, osteoporosis
- hypercalcaemia: fatigue, weakness, thirst, renal stone, abdominal pain, pancreatitis, depression
primary hyperparathyroidism diagnosis
- 24 hour urinary calcium
- blood: increased PTH, calcium, low PO4
- imaging: sesatimbi scan to visualise glands
primary hyperparathyroidism diagnostic criteria
- hypercalcaemia, high PTH
- normal UE
- high urine calcium
- not on lithium or thiazide
primary hyperparathyroidism management
- watchful waiting
- surgical removal of adenoma or all four parathyroid glands (total parathyroidectomy)
what is secondary hyperparathyroidism
physiological response to low serum calcium, with the increase seen being appropriate to the deficit
what is tertiary hyperparathyroidism
hyperplastic changes in the parathyroid glands in response to prolonged hypocalcaemia
secondary and teriarty hyperparathyroidism causes
- vitamin D deficiency
- chronic kidney disease
secondary and tertiary hyperparathyroidism pathophysiology
elevated PTH in response to hypocalcaemia
secondary hyperparathyroidism diagnosis
- low calcium
- high PTH
- high PO4
tertiary hyperparathyroidism diagnosis
- high calcium
- very high PTH
- low PO4
secondary and tertiary hyperparathyroidism management
- treat underlying cause
- renal disease: diet restriction, phosphate binders
what is malignant hyperparathyroidism
- parathyroid related protein released by following cancers: small cell lung, renal and breast
- protein mimics PTH and acts to increase serum calcium
malignant hyperparathyroidism diagnosis
- high calcium
- low PTH
what is hypoparathyroidism
low PTH due to gland failure
hypoparathyroidism causes
- decrease Mg2+
- autoimmune
- DiGeorge syndrome
- haemochromatosis/Wilson’s
- iatrogenic: thyroid surgery or radio-ablation
hypoparathyroidism presentation
- hypocalcaemia
- numbness
- muscle cramps
- spasms
- wheeze
- anxiety
hypoparathyroidism diagnosis
- low calcium
- low PTH
- high PO4
hypoparathyroidism management
- treatment of underlying cause
- calcium and vitamin D supplements
what is pseudohypoparathyroidism
genetic condition associated with peripheral resistance to PTH
pseudohypoparathyroidism presentation
- low IQ
- obesity
- short stature
- bradydactylyl of 4th metacarpal
pseudohypoparathyroidism diagnosis
- low calcium
- high PTH
- high PO4
pseudohypoparathyroidism
calcium and vitamin D supplements
what is psuedo pseudohypoparathyroidism
genetic condition (may be associated with some of the morphological features of pseudo-hypoparathyroidism but with normal biochemistry)
pseudo pseudohypoparathyroidism diagnosis
- normal calcium
- high PTH
- normal PO4
hypercalcaemia causes
- dehydration
- parathyroid disease
- familial hypocalciuric hypercalcaemia (autosomal dominant condition associated with reduction in calcium sensing abilities of parathyroid glands. produces mild but symptomatic hypercalcaemia. may be associated with recurrent episodes of pancreatitis)
- bone pathology: malignancy, myeloma, vitamin D excess
- drugs: thiazides
hypercalcaemia presentation
- bones, stones, groans and psychiatric moans
- fatigue, weight loss, thirst
- polyuria, dehydration
- abdominal pain, vomiting, constipation
- osteoporosis, weakness
- kidney stones, renal failure
- confusion, depression
hypercalcaemia general diagnosis
- bloods (always check PTH)
- urine: 24 hours urinary calcium
- ECG: short QT interval
hypercalcaemia caused by dehydration diagnosis
raised albumin and urea
hypercalcaemia caused by familial hypoalciuric hypercalcaemia diagnosis
- normal or low albumin
- normal or high PTH
- high urinary calcium
hypercalcaemia caused by bone metastasis diagnosis
- normal or low albumin
- high PO4
- low PTH
- high ALP
hypercalcaemia caused by myeloma or vitamin D excess diagnosis
- normal or low albumin
- high PO4
- low PTH
- normal ALP
hypercalcaemia management
- acute hypercalcaemia: rehydration and bisphosphonates (IV pamidronate)
- treat underlying cause
- increase fluid intake
- working out the cause
hypocalcaemia with associated increased PO4 causes
- hypoparathyroidism
- pseudo-hypoparathyroidism
- vitamin D deficiency
- chronic kidney disease
- low magnesium
hypocalcaemia with normal or decreased PO4 causes
- osteomalacia
- acute pancreatitis
- over hydration
- respiratory alkalosis
hypocalcaemia presentation
- dry skin
- peri-oral paraesthesia, seizures
- muscle weakness, spasms of hands of feet
- increased smooth muscle tone: wheeze, dysphagia, colic
- anxiety, irritability, irrational behaviour, confusion, disorientation
hypocalcaemia diagnosis
- ECG: long QT interval
- Choystek’s sign:
- trousseau’s sign
what is Choystek’s sign
twitching of corner of mouth on tapping the facial nerve over the parotid
what is trousseau’s sign
inflation of blood pressure cuff above systolic causes spasms of the hand
hypocalcaemia acute/severe management
calcium gluconate
hypocalcaemia chronic/mild management
calcium and vitamin D supplements
