Calcium

Question 1

How do PTH, vitamin D and calcitonin affect serum calcium concentration?

Answer 1

A) Low serum calcium concentrations stimulate the release of PTH, which increases bone resorption, augment renal conservation of calcium, and activate vitamin D, which increases intestinal absorption of calcium.

B) Calcitonin is released by the thyroid in response to elevated serum concentrations and acts to inhibit bone resorption and increase urinary calcium excretion.

Question 2

What are normal total serum calcium concentration?

Answer 2

8.6 to 10.2 mg/dl or ionized calcium conc 1.12 to 1.3 mmol/L

Question 3

How do serum pH, phosphorus and albumin levels affect the percentage of ionized calcium?

Answer 3

A metabolic alkalosis decreases the % of calcium, as does an increase in serum phosphorus.
Hypo albuminemia decreases total serum calcium but does not affect ionized calcium levels.
NB: the most accurate method for assessing calcium abnormalities is to measure ionized calcium.

Question 4

What is hypocalcemia?

Answer 4

Hypocalcemia is defined as total serum calcium conc of

Question 5

What are some causes of hypocalcemia?

Answer 5

1. Decreased vit D activity ( vit D def, hyperphosphatemia, pseudohypoparathyroidism)
2. Decreased PTH activity (acute pancreatitis, hypomagnesemia, hypoparathyroidism) and hungry bone syndrome.
3. Hypocalcemia is common in critically ill patients and is associated with sepsis, rhabdomyolysis and massive blood transfusion.
4. Drugs can also be related to hypocalcemia.

Question 6

What drugs are associated with hypocalcemia?

Answer 6

Drugs implicated in the etiology of hypocalcemia are:biphosphonates, calcitonin, furosemide, foscarnet, and long-term therapy with phenobarbital and phenytoin.

Question 7

What are clinical manifestations of hypocalcemia?

Answer 7

Clinical manifestations may be cardiovascular or neuromuscular.

Question 8

1. What is severe hypocalcemia?

2. How do we treat severe hypocalcemia or acute symptomatic hypocalcemia?

Answer 8

1. Severe hypocalcemia is defined as

Question 9

What are the guideline for the treatment of acute hypocalcemia?

Answer 9

1 - 1.12 mmol/L –> 2g calcium gluconate over 2 hrs

4g calcium gluconate over 4 hrs

Question 10

How do you treat chronic or asymptomatic hypocalcemia?

Answer 10

Chronic or asymptomatic hypocalcemia can be treated with oral calcium supplements and vitamin D

Question 11

1. What is hypercalcemia?

2. What are some common causes of hypercalcemia?

Answer 11

1. Hypercalcemia is defined as

Question 12

1. What is mild hypercalcemia?

2. How do we treat mild hypercalcemia?

Answer 12

1. Mild hypercalcemia is 10.3 - 12.9 mg/dl (total serum calcium conc) or 1.31 - 1.49 mmol/l (ionized calcium).
2. Mild hypercalcemia usually responds well to hydration and ambulation.

Question 13

1. What is severe hypercalcemia?

2. How do we treat severe hypercalcemia?

Answer 13

1. Severe hypercalcemia is >12.9 mg/dl (total serum calcium conc) or