Calcium homeostasis Flashcards
What factors effect calcium homeostasis?
Dietry intake
Gut absorption
PTH
Vit D
How is vitamin D produced in the body?
Dehydrocholesterol (skin, UV)
To cholecalciferol (D3, to liver)
To 25(OH)Vit D (to kidney)
To 1,25 (OH) Vit D (to rest of body)
What are the acute/ chronic symptoms of hypercalcaemia?
Acute: Thirst Dehydration Confusion Polyuria
Chronic: Myopathy Osteopaenia Fractures Depression Hypertension Abdo pain (pancreatitis,ulcers,renal stones)
What are the causes of hypercalcaemia?
Primary hyperparathyroidism Malignancy Vit D Thiazides Hypocalcuric Hypercalcaemia High turnover (paget's, bedridden, thyrotoxic) Tertiary hyperparathyroid
How is primary hyperparathyroidism diagnosed?
Raised serum Ca2+
Raised serum PTH
Increase urine Ca2+
How is malignancy hypercalcaemia diagnosed?
Raised Ca2+ and ALP
Xray, CT, MRI
Isotope bone scan
Why do you get hypercalcaemia in malignancy?
Bone mets
PTHrp from solid tumours
osteoclast activating factors
How is acute hypercalcaemia treated?
0.9% saline, rehydrate, 4-6L/24hr
Loop diuretic once rehydrated (not thiazide)
Bisphophonates (single dose, max effect 1 week)
Steriods ocasionally (sarcoid)
Chemo (myeloma)
How is primary hyperparathyroidism managed?
Surgery or nothing
not always required
What are the indications for parathyroidectomy?
End organ damage
very high Ca2+ (>2.85)
Under 50yrs
eGFR <60
What are the PTH and Ca2+ levels in
a) primary hyperparathyroid
b) secondary hyperparathyroid
c) tertirary hyperparathyroid?
a) PTH up, Ca2+ up
b) Ca2+ low, PTH up
c) Ca up, PTH up (autonomous after years of 2ndary)
What is the algorithm when assesing cause of hepercalcaemia?
Raised Ca2+
Albumin
Phosphates
Alk Phosph
What is hypocalciuric hypoecalcaemia?
Autosomal DOminant Usually asymptomatic mild hyperCa2+ reduced Ca2+ in urine PTH (marginally) up
What are the symptoms of hypercalcaemia?
Paraesthesia
What is hypocalciuric hypercalcaemia?
Autosomal DOminant Usually asymptomatic mild hyperCa2+ reduced Ca2+ in urine PTH (marginally) up
What are the symptoms of hypocalcaemia?
Paraesthesia (fingers, toes, perioral) Muscle cramps (tetany) Muscle weakness Fatigue Broncho/laryngospasm fits Chovsteks sign Trousseau sign QTprolongation
What can cause hypocalcaemia?
Hypoparathyroid Vit D deficiency CKD Pancreatitis Hyperventilation Osteoblastic bone mets Rhabdomyolysis
What is the treatment for acute hypocalcaemia?
IV calcium gluconate (10ml, 10% over 10 mins)
in 50ml saline or dextrose
Infusion, (10ml, 10% in 100ml at 50ml/hr)
What are the causes of hypoparathyroidism?
Congenital absence (diGeorge) Destruction(surgery, radio) Autoimmune Hypomagnesaemia idiopathic
What is the long term management of hypocalcaemia?
Calcium supplement
Vit D tablets (alpha caldidol tablets or cholecalciferol injection)
What is pseudohypoparathyridism?
Genetic defect of Gprotein Gs alpha (GNAS1)
What are the hormone levels in pseudohypoparathyridism?
Low Ca2+
high PTH
(PTH resistance)
What are the signs of pseudohypoparathyridism?
Bone abnormalities Obesity Subcut calcification Mental retardation 4th metacarpal brachdactyly
What is pseudo-pseudohypoparathyroidism?
same as pseudo but with normal Ca2+
patients can become pseudo pseudo
What conditions are caused by Vit D deficiency?
rickets
osteomalacia
What can cause Vit D deficiency?
Dietary Malabsorption CKD Lack of sun Anticonvulsant drugs
