Bones Flashcards
Describe vit D pathway
UV + diet
=>
vit D
=> (25-hydroxylase from liver)
calcitriol
=> (1-alpha-hydroxylase from kidney) + PTH
calcitriol
Which hormones control calcium metabolism?
To increase calcium (+ decrease phosphates)
- PTH (parathyroid glands), calcitriol (skin + UV light)
To decrease calcium
- calcitonin (parafollicular cells)
Types of hyperparathyroidism, incl. which calcium imbalance they cause
Primary
- hyperplasia, adenoma/carcinoma
- increased PTH => increased Ca2+
- hypercalcaemia
Secondary
- vit D deficiency, decreased calcium intake
- low Ca2+ => less neg. feedback => increased PTH
- hypocalcaemia
Compare sx of hypo and hypercalcaemia
Hypocalcaemia (CATS go numb)
- C onvulsions
- A rrhythmias (prolonged QT interval)
- T etany (Trousseau’s hand + Chvostek’s cheek)
- P araesthesia (hands, mouth, feet, lips)
Hypercalcaemia (stones, nones, thrones, abdo moans, psychiatric overtones)
- renal stones
- bone pain/damage
- polyuria
- abdo (nausea and constipation pain)
- psych (depression, anxiety)
- also a cause of pancreatitis!!
RFs for primary hyperPTH
HTN
MEN-1 or MEN-2
Signs and sx for secondary hyperPTH
Rickets/osetomalacia
- bowed legs, knock knees, rachitic rosary, bone bossing
Hypocalcaemia
Fractures/bone pain
Fatigue
Proximal myopathy
Ix for hyperPTH
Basic obs
Physical exam
Bloods
- FBC, CRP, U&Es, LFTs, Ca2+, PO43-, PTH, vit D
Imaging
- CT KUB (for stones), cervical US, X-ray/CT
=> primary: pepper pot skull
=> secondary: rachitic rosary, boser’s pseudofractures
State the calcium, phosphate, PTH, vit D and ALP reading for:
a) primary hyperPTH
b) ostemolacia (vit D)
c) osteomalacia (CKD)
d) Paget’s
e) osteoporosis
Readings for calcium, phosphate, PTH, vit D, ALP:
a) high, low, high/normal, normal, high/normal
b) low, low, high, low, high
c) low, high, high, low, high
d) normal, normal, normal, normal, high
e) normal, normal, normal, normal, normal
Mx for hyperPTH
Primary
- acute hypercalcaemia: IV fluids, biphosphonates (if calcium remains high)
- surgical (1st line): totaly parathyroidectomy
- medical: cinacalet (if unsuitable for surgery, calcimimetic drug)
Secondary
- due to CKD
=> treat CKD, calcium, vit D active (alfacalcidol)
- due to vit. D
=> treat hypocalcaemia (IV calcium infusion, calcium gluconate), calcium, vit D inactive (ergocalciferol)
Phases of Paget’s disease
Disorder of bone remodelling
I. Lytic phase
- hyperactive osteoclasts => reabsorption
II. Mixed phase
- compensation by osteoblasts
III. Sclerotic phase
- hyperactive osteoblasts => formtaion
Produces WOVEN bone, not lamellar
Paget’s disease signs + sx
Sx: nerve compression, bone pain (femur, pelvis, skull), otherwise often asymptomatic (until sciatica and sensorineural hearing loss)
Signs: thoracic kyphosis, warm skin over painful area (increased metabolic activity), bone bossing (femur, tibia, skull)
Paget’s disease ix
Basic obs
Physical examination
Bloods
- FBC, CRP, U&Es, PTH, phosphate, calcium, vit D, serum CTX (bone resorption marker), serum P1NP (bone formation marker)
Imaging
- X-rays, bone scan (tec99) => hot spots in lytic areas
Osteoporosis causes
Primary
- postmenopausal
- old age
Secondary
- drugs: thyroxine, steroids
- endo: hyperT, osteomalacia, Cushing’s disease
- cancer: multiple myeloma
- MSK: SLE, RA
- GI: IBD, coeliac disease
Osteoporosis signs, sx and ix
Fractures (often NOF), back pain, thoracic kyphosis
Basic obs, physical exam, bloods (FBC, CRP, U&Es, LFTs (ALP), calcium, phosphate, PTH, vit D), imaging (X-rays, DEXA scan)
What are the DEXA scan ranges?
T-score used to compare to young, healthy adult
Z-score used to compare to age-matched BMD
T-score:
0 - -1 = normal
-1 - -2.5 = osteopaenia
>-2.5 = osteoporosis