Revision Flashcards
2 hormones that increase calcium levels
PTH
Calctriol (vit D)
Which hormone decreases calcium? Where is this produced?
Calcitonin - parafollicular cells
Explain how vit D becomes activated
Vit D from diet and UV light is hydoxylated by liver to 25-hydroxy vit D.
Rate limiting step - this is then hydroxylated into activated vitamin D (calctriol) by 1alpha hyroxylase, which itself is activated by PTH.
What is the effect of PTH on the bone, kidneys and small intestines? What is the overall effect?
Bone - increased resportion
Small intestines - increased absorption of calcium
Kidneys - increased calcium reabsorption and phosphate EXCRETION.
Overall effect - increased calcium, decreased phosphate
What is the effect of calctriol on the bone, kidneys and small intestines? What is the overall effect?
Kidneys - increased calcium reabsorption
Bone - increased formation
Small intestines - increased calcium AND phosphate reabsorption
Overall - INCREASED calcium and phosphate
Which hormone is better at increased calcium and dropping phosphate?
Vit D - better at increasing calcium than PTH
PTH - better at dropping phosphate (phosphate trashing hormone)
PTH, ALP calcium and phosphate levels in primary hyperparathyroidism
High or INAPPROPRIATELY NORMAL PTH
Low phosh
High calcium
Normal ALP
PTH, ALP calcium and phosphate levels in secondary hyperparathyroidism due to Vit D deficiency
Vit D low therefore:
Low calcium
Low phosphate
High PTH
High ALP because released by bone (osteomalacia)
PTH, ALP calcium and phosphate levels in secondary hyperparathyroidism due to CKD
Kidneys not functioning, therefore:
High PTH
Low Calcium
However, high phosphate as kidneys can’t excrete it
PTH, ALP calcium and phosphate levels in tertiary hyperparathyroidism
Tertiary hyperparathyroidism is secondary to CKD, therefore:
High PTH High calcium (no negative feedback) High phosphate (because kidneys can't excrete it)
If phosphate is low, what are you thinking?
Vit D deficiency or primary PTH
If phosphate is high, what are you thinking?
CKD
If calcium is high too - tertiary
If calcium low - secondary
Other causes of hypercalcemia
Malignancy
- Bone mets
- Haem - multiple -myeloma (CRAB)
- Paraneoplastic - lung squamous cell cancer
Sarcoidosis
Thiazide diuretics
Multiple myeloma acronym
Calcium high
Renal failure
Anemia
Bone disease
Low PTH causes of low calcium
Surgical complications
Autoimmune hypoparathyroidism
High PTH + low calcium
Osteomalacia (secondary hyperPTH)
Low calcium symptoms
Convulsions
Arrhythmias - prolonged QT
Tetany (increased nerve conduction)
Paraesthesia - numb hands, mouth, feet, lips
CATS go numb
Signs of hypocalcemia
Trousseau’s sign - spasm when tightening BP cuff
Chvostek’s sign - twtiching when touching facial nerve
Which is more likely to be found in pancreatitis - hyper or hypocalcaemia?
Hypocalcemia due to saponification
High calcium causes pancreatitis but then it gets deposited.
Risk factors for primary hyperparathyroidism
MEN 1 or 2
Hypertension
MEN 1 complications
Pancreatic tumours
Parathyroid hyperplasia
Pituitary adenomas
MEN 2 complications
Parathyroid hyperplasia
Phaeo
Medullary thyroid cancer
Causes of secondary hyperparathyroidism besides lack of sunlight/dietary intake if vit D
Crohns/Coeliac
CKD
Liver disease
Symptoms on secondary hyperparathyroidism in adults
Fractures/bone pain
Proximal myopathy (weakness)
Fatigue
Hypocalcemia symptoms - convulsions, arrhythmias, tetany, numbness
Invx
USS of parathyroid
XR/CT
Bn
XR findings in primary hyperparathyroidism
Subperiosteal bone resorption
Acro-osteolysis (erosions of finger tips)
Pepper pot skull
XR findings in secondary hyperparathyroidism
Swelling of constrochondral junctions - rachitic rosary
Looser’s pseudofractures - doesn’t go all teh way
Treatment of acute hypercalcemia in primary hyperPTH
IV fluids
Bisphosphonates if calcium remains high
Treatment of hypercalcemia in primary hyperPTH once pt is stable
Total parathyroidectomy
SE: risk of recurrent laryngeal nerve -> hoarseness
What do you give if a a patient with primary hyperPTH is unsuitable for surgery?
Cinacalcet, calcimimetic i.e. tries to do negative feedback against PTH like calcium
Secondary hyperPTH management in acute hypocalcemia
IV calcium infusion - calcium gluconate
What else is calcium gluconate used for?
Hyperkalemia
What would you give to a pt with secondary hyperPTH once they are stable?
Calcium
Vit D - ergocalciferol (inactive form)
How do you manage a pt with secondary hyperPTH with CKD once they are stable?
Calcium
Vit D - alfacalcidol (active)
Treat CKD
Three phases of paget’s disease
Lytic phase (hyperactive osteoclasts causing resorttion) Mixed phase Sclerotic phase (hyperactive osteoblasts - woven bone, not lamellar)
Symptoms of Pagets
Often asymptomatic
Fragility fractuers
Bone pain - skull, femur, pelvis
Nerve compression due to osteoblasts reforming the bone in areas where there used to be foramina - sensorineural hearing loss, sciatica
Signs of Paget’s
Warm skin over painful area (high metabolism)
Bone enlargement
Blood findings in Paget’s
High ALP, everything else normal
Name a bone resorption marker used in Pagets
Serum CTX
Name a bone formation marker used in Pagets
Serum P1NP
Imaging for pagets
XR
Tec99 scan - hot spots seen in high functioning areas of bone
PE scan if pregnant
V/Q scans
Osteoporosis primary causes
Menopause
Elderly
Osteoporosis secondary causes
Drugs: - Steroid use - Thyroxine - Alcohol Endo causes: - Cushing's - Hyperparathyroidism - Hyperthyroidism GI causes - Coeliac disease - IBD
Signs and symptoms in osteoporosis
Often asymptomatic Fragility fractures
Back pain
Osteoporosis fractures (four)
NOF
Colles wrist fracutre
Lumbar spine wedge fracture
Neck of humerus
Imaging for osteoporosis
DEXA scan
XR
Blood results for osteoporosis
Everything normal
What are the two types of scores used in DEXA? Which of these is most important?
T score - patient’s BMD compared to young, healthy adults - most important
Z score - patient’s BMD compared to age matched BMD
What numbers are key in diagnosing osteoporosis and also the stage before that, using DEXA scans?
- 1 to -2.5 -> osteopenia
- 2.5 or above - osteoporosis
What is the DEXA score used to calculate?
The FRAX score aka 10 year risk of developing fragility fractures; decides management
Looser’s pseudofracture
low vit D and calcium
Osteoporosis mx
Bisphosphonates
Recombinant PTH - teriparatide
