Chemical Pathology: Calcium

Question 1

Calcium:

What are normal blood calcium levels?

What form does it take in the blood?

Answer 1

Question 2

Calcium:

What are the two main hormones involved in Calcium Metabolism and what do they do?

Answer 2

• PTH:
  
  • Stimulates 1-alpha hydroxylase to convert 25-hydroxycholecalciferol into 1,25-dihydroxycalciferol/Calcitriol/ (Acitvated Vitamin D)
• Clacitriol is also called:
  
  • 1,25-dihydroxycalciferol

Question 3

Calcium:

Outline the overall Calcium feedback loop

Answer 3

Question 4

Calcium:

Outline the Primary Defect, Calcium Level, Phosphate level, Alk Phos level and Vitamin D levels for Primary Hyperparathyroidism

Answer 4

• A disorder of the Parathyroids where excessive PTH is produced

Question 5

Calcium:

Outline the Primary Defect, Calcium Level, Phosphate level, Alk Phos level and Vitamin D levels for Secondary Hyperparathyroidism

Answer 5

• Secondary Hyperparathyroidism is high PTH levels in response to Hypocalcaemia

Question 6

Calcium:

Outline the Primary Defect, Calcium Level, Phosphate level, Alk Phos level and Vitamin D levels for Tertiary Hyperparathyroidism

Answer 6

• Tertiary hyperparathyroidism is a state of excessive secretion of PTH after a long period of secondary hyperparathyroidism and resulting in a high blood calcium level. It reflects development of autonomous/unregulated parathyroid function following a period of persistent parathyroid stimulation.

Question 7

Calcium:

Outline the Primary Defect, Calcium Level, Phosphate level, Alk Phos level and Vitamin D levels for Hypoparathyroidism

Answer 7

Question 8

Calcium:

Outline the Primary Defect, Calcium Level, Phosphate level, Alk Phos level and Vitamin D levels for Rickets/Osteomalacia

Answer 8

Question 9

Calcium:

Outline the Primary Defect, Calcium Level, Phosphate level, Alk Phos level and Vitamin D levels for Paget’s disease

Answer 9

Question 10

Calcium:

Outline the Primary Defect, Calcium Level, Phosphate level, Alk level and Vitamin D levels for Osteoporosis

Answer 10

Question 11

Calcium:

What are the causes of Hypocalcaemia?

Answer 11

Question 12

Calcium:

What is/are the symptoms and treatment of Hypocalcaemia?

Answer 12

Question 13

Calcium:

What are the causes of Hypercalcaemia?

Answer 13

Question 14

Calcium:

What is/are the symptoms and treatment of Hypercalcaemia?

Answer 14

Question 15

Calcium:

What are the risk factors for Renal stones?

Answer 15

Question 16

Calcium:

What is/are the signs, causes and preventative management of Calcium Stones?

Answer 16

Hyperoxaluria: excessive urinary excretion of oxalate

Question 17

Calcium:

What is/are the % frequency and X-ray appearance of:

1. Mixed Calcium stones
2. Calcium oxalate
3. Calcium phosphate
4. Triple phosphate“Struvite”
5. Uric acid
6. Cysteine
7. Others eg xanthine

Answer 17

Question 18

Calcium:

What are the investigations for recurrent stones?

Answer 18

MCS = Microscopy Culture Sensitivities

Question 19

Calcium:

Outline Vitmain D Synthesis

Answer 19

Vitamin D3 is made in the skin as cholecalciferol, which is converted into 25-hydroxycholecalciferol by 25 hydroxylase from the Liver. This is then converted into 1,25-dihydroxycholecalciferol 25-(OH)2 D3 by 1 aphla hydroxylase from the kidney.

Question 20

Calcium

What are the roles of Vitamin D?

Answer 20

1,25-dihydroxycholecalciferol, Vitamin D roles:

• Intestinal Calcium absorption
• Intestinal Phosphate absorption
• Bone formation
• Cells have important Vit D receptors to control genes, cell proliferation, immune system and such

Question 21

Caclcium

What is corrected Calcium?

How is it calculated?

Why is it needed?

Answer 21

• Total serum Calcium is between 2.2 - 2.6 mmol/L.
• Because calcium binds to albumin and only the unbound (free or ionized) calcium is biologically active, the serum level must be adjusted for abnormal albumin levels.
• Corrected calcium can be given, which is serum Calcium + 0.02 x (40-serum albumin in g/L).
  
  • Ionised calcium can also be given but not from a lab since the blood clots.
• With a low albumin, the bound calcium will show as low but the free will be normal. The corrected calcium refers to this.

Question 22

Calcium

What is Pseudohypoparathyroidism?

Answer 22

• Pseudohypoparathyroidism is a condition associated primarily with resistance to PTH
• Those with the condition have a low serum calcium and high phosphate, but the parathyroid hormone level (PTH) is appropriately high (due to the low level of calcium in the blood).