w4 - calcium metabolism Flashcards
t.f low calcium inhibits PTH production
false
hydroapatite que?
too mch?
mineralising building block of bone
too much? -ve feedback, no more inorganic phosphate
anticonvulsants effect on kidneys
stops vit d absorption
symptoms of hypercalcaemia
bones
stones
ab groans
psychic moans
acute signs of hypercal
Thirst
Dehydration
Confusion
Polyuria
chronic signs o/symptoms of hypercal
Myopathy Fractures Osteopaenia Depression Hypertension Pancreatitis DU Renal calculi
causes of hypercal
Drugs: Vit D, thiazides Granulomatous Disease eg Sarcoid, TB Familial Hypocalciuric Hypercalcaemia High turnover: bedridden, thyrotoxic, Pagets Others Tertiary hyperparathyroidism
3 things to iagnose hyperpara
raised serum Ca
raised serum PTH (or inapp. normal)
incr urine calcium excretion (ensure Vit D replete)
hypercalcaemi can happen in malignancy, 3 ways
metastatic bone destructiin
PTHrp from solid tumours
osteoclast activating factors
diagnosed: raised ca and alkaline phosphatase, imagin, isotope bone scan
acute tx of hypercal
fluids - rehydrate (0.9% saline 4-6L 24hr)
Consider loop diuretics once rehydrated- avoid thiazides
Bisphosphonates- single dose will lower Ca over 2-3d, maximum effect at 1 week
Steroids occasionally used e.g Pred 40-60mg/day for sarcoidosis
Salmon calcitonin- rarely used
Chemotherapy may reduce calcium in malignant disease e.g. myeloma
when is sestamibi scan used
only if gonna remove parathyroid
management of primary hyperparathyroidsm
surgery - not always required
Cinacalcet
Cacium Mimetic
Can be useful if need treatment, but unfit for surgery
Licensed, but not SMC approved
Approved for tertiary hyperparathyroidism and parathyroid carcinoma
parathyroidectomy indicated when
End Organ Damage: Bone disease (Osteitis Fibosa et cystica; brown tumours/ pepper pot skull) Gastric ulcers Renal stones Osteoporosis
Very high Calcium (>2.85mmol/l)
Under age 50
eGFR < 60 mL/min
Non-pulsatile delivery of any hormone will cause __ __of usual delivery
opposite effect
t.f 2ndary hyperpara wil result in low calcium and high PTH
true
tertiary hyperpara will cause high cal and low pth
false
high cal and pTH (like primary)
Parathyroid becomes autonomous after many years of overactivity e.g renal failure
which genetic syndromes will cause hyperpars
men1/2
signs and symptoms of hypocal
Paraesthesia - fingers, toes, perioral Muscle cramps, tetany Muscle weakness Fatigue Bronchospasm or laryngospasm Fits Chovsteks sign (tapping over facial nerve) Trousseau sign (carpopedal spasm) =
QT prolongation is seen in hypocal t.f
true
emergency treatment for acute hypocal
Emergency: IV calcium gluconate 10 ml, 10% over 10 mins (in 50ml saline or dextrose)
Infusion (10ml 10% in 100 ml infusate, at 50 ml/h)
congential absence of hypopara
digeorge syndrom
long term management of hypopara
Calcium supplement : > 1-2 g per day
Vitamin D Tablets:
1 alphacalcidol 0.5-1 mcg (sometimes more)
Depot injection: Cholecalciferol 300,000 units 6 monthly
how does hypomagnasaemia cause hypopara
Calcium release from cells is dependent on magnesium
In magnesium deficency intracellular calcium is high
PTH release in inhibited
Skeletal and muscle receptors less sensitive to PTH
If low replace with calcium and magnesium
causes of hypomag
Alcohol Drugs Thiazide PPI GI illness Pancreatitis Malabsorption
pseudohypopara
genetic defect leading to hypopara
Pseudo-pseudohypoparathyroidism
Herditary Osteodystrophy
No alteration in PTH action and thus
Normal calcium
pain described in osteomalacia
deep bony ache
loosers zones
weak bne
neck of femur
sign on imaging
2 big things chronic renal disease will causeq
vit d def
2ndary hypopara
t.f chronic renal will have low 25-OH Vit d
false
high
but cant change to 1-25OH vitD
another name for vitd -resistant rickets
x-linked hypophosphataemia
