Calcium homeostasis

Question 1

What factors effect calcium homeostasis?

Answer 1

Dietry intake
Gut absorption
PTH
Vit D

Question 2

How is vitamin D produced in the body?

Answer 2

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)

Question 3

What are the acute/ chronic symptoms of hypercalcaemia?

Answer 3

Acute: 
Thirst
Dehydration
Confusion
Polyuria

Chronic:
Myopathy
Osteopaenia
Fractures
Depression
Hypertension
Abdo pain (pancreatitis,ulcers,renal stones)

Question 4

What are the causes of hypercalcaemia?

Answer 4

Primary hyperparathyroidism
Malignancy
Vit D
Thiazides
Hypocalcuric Hypercalcaemia
High turnover (paget's, bedridden, thyrotoxic)
Tertiary hyperparathyroid

Question 5

How is primary hyperparathyroidism diagnosed?

Answer 5

Raised serum Ca2+
Raised serum PTH
Increase urine Ca2+

Question 6

How is malignancy hypercalcaemia diagnosed?

Answer 6

Raised Ca2+ and ALP
Xray, CT, MRI
Isotope bone scan

Question 7

Why do you get hypercalcaemia in malignancy?

Answer 7

Bone mets
PTHrp from solid tumours
osteoclast activating factors

Question 8

How is acute hypercalcaemia treated?

Answer 8

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)

Question 9

How is primary hyperparathyroidism managed?

Answer 9

Surgery or nothing

not always required

Question 10

What are the indications for parathyroidectomy?

Answer 10

End organ damage
very high Ca2+ (>2.85)
Under 50yrs
eGFR <60

Question 11

What are the PTH and Ca2+ levels in

a) primary hyperparathyroid
b) secondary hyperparathyroid
c) tertirary hyperparathyroid?

Answer 11

a) PTH up, Ca2+ up
b) Ca2+ low, PTH up
c) Ca up, PTH up (autonomous after years of 2ndary)

Question 12

What is the algorithm when assesing cause of hepercalcaemia?

Answer 12

Raised Ca2+
Albumin
Phosphates
Alk Phosph

Question 13

What is hypocalciuric hypoecalcaemia?

Answer 13

Autosomal DOminant
Usually asymptomatic
mild hyperCa2+
reduced Ca2+ in urine
PTH (marginally) up

Question 14

What are the symptoms of hypercalcaemia?

Answer 14

Paraesthesia

Question 15

What is hypocalciuric hypercalcaemia?

Answer 15

Autosomal DOminant
Usually asymptomatic
mild hyperCa2+
reduced Ca2+ in urine
PTH (marginally) up

Question 16

What are the symptoms of hypocalcaemia?

Answer 16

Paraesthesia (fingers, toes, perioral)
Muscle cramps (tetany)
Muscle weakness
Fatigue
Broncho/laryngospasm
fits
Chovsteks sign
Trousseau sign
QTprolongation

Question 17

What can cause hypocalcaemia?

Answer 17

Hypoparathyroid
Vit D deficiency
CKD
Pancreatitis
Hyperventilation
Osteoblastic bone mets
Rhabdomyolysis

Question 18

What is the treatment for acute hypocalcaemia?

Answer 18

IV calcium gluconate (10ml, 10% over 10 mins)
in 50ml saline or dextrose
Infusion, (10ml, 10% in 100ml at 50ml/hr)

Question 19

What are the causes of hypoparathyroidism?

Answer 19

Congenital absence (diGeorge)
Destruction(surgery, radio)
Autoimmune
Hypomagnesaemia
idiopathic

Question 20

What is the long term management of hypocalcaemia?

Answer 20

Calcium supplement

Vit D tablets (alpha caldidol tablets or cholecalciferol injection)

Question 21

What is pseudohypoparathyridism?

Answer 21

Genetic defect of Gprotein Gs alpha (GNAS1)

Question 22

What are the hormone levels in pseudohypoparathyridism?

Answer 22

Low Ca2+
high PTH

(PTH resistance)

Question 23

What are the signs of pseudohypoparathyridism?

Answer 23

Bone abnormalities
Obesity 
Subcut calcification
Mental retardation
4th metacarpal brachdactyly

Question 24

What is pseudo-pseudohypoparathyroidism?

Answer 24

same as pseudo but with normal Ca2+

patients can become pseudo pseudo

Question 25

What conditions are caused by Vit D deficiency?

Answer 25

rickets

osteomalacia

Question 26

What can cause Vit D deficiency?

Answer 26

Dietary
Malabsorption
CKD
Lack of sun
Anticonvulsant drugs