Biochemistry 3

Question 1

Hypercalcaemia

Answer 1

Often clinically silent
Wide range of symptoms: polyuria, excessive thrust, lethargy, peptic ulceration, GI, depression
Malignancy (bone metastases- tumour cells in bone) and primary hyperparathyriodism account for 90% of cases

Can also be cause by parathyroid hormone

Question 2

Severity of hypercalcaemia

Answer 2

<3.0 mmol/L often asymptomatic usually doesn’t need urgent correction

3.0-3.5 mmol/L may be tolerated if rise was slow, may be symptomatic and treatment usually needed

> 3.5mmol/L requires urgent correction due to risk of dysrhythmia and coma

Question 3

Hypercalcaemia: treatment

Answer 3

Treat underlying cause

Rehydrate with saline to increase output of calcium (4-6L) over 24 hours

May need dialysis if severe renal failure
After hydration, IV bisphosphonate to reduce bone turnover

Question 4

Metabolic bone disease

Answer 4

OSTEOPOROSIS- no increase in Ca, PO4 or alk phos

Paget’s disease- no increase in Ca, PO4 but large increase in alk phos

Osteomalacia- decrease in Ca and PO4 and increase in alk phos

Question 5

Paget’s

Answer 5

Increased bone turnover

Increased osteoblast, clasts

Bone deformity: skull, tibia, fibula, pelvis

Question 6

Osteomalacia

Answer 6

Ricketts

Not enough minerals in the bones, curved legs

Question 7

Magnesium

Answer 7

Predominately an intracellular cation
Reference range 0.7-1.0 mmol/L
Hypomagnesaemia is common but often asymptomatic, but associated with hypokalaemia and hypocalcaemia
Treat if <0.4 mmol/L or >0.4 mmol/L if symptomatic
No national guidelines on how to treat abnormalities
Most is ion form some in bone form

Question 8

Drugs causing magnesium abnormalities

Answer 8

Hypomagnesaemia: thiazide diuretics (interfere with renal absorption of Mg)
Drugs causing nerphrotoxicity: CIS-platin, gentamicin
PPIs- don’t no how it works