Endocrinology

Question 1

What are the effects of parathyroid hormone?

Answer 1

Bone

• Increase osteoclastic resorption of bone
• Therefore: increases release of Ca and PO4

Kidney

• Increase calcium resabsorption by distal convoluted tubule
• Decrease PO4 reabsorption by proximal convoluted tubule
• Increase expression and stimulation of 1-alpha hydroxylase to increase activation of 24,25-(OH)2D3 into 1,25-(OH)2D3

Question 2

What happens to the bone profile in chronic renal disease?

Answer 2

Secondary hyperparathyroidism

• Decreased activity of 1-alpha-hydroxylase>> Decreased serum calcium
  >> Increased serum phosphate
• Decreased functioning of the nephrones
  >> Increased serum phosphate