Hormonal Aspect of the Kidneys

Question 1

List the causes of release of erythropoietin by the kidneys

Answer 1

• If kidney becomes hypoxic
• Being at altitude,
• Loss of RBCs due to haemorrhage/excessive RBCs destruction and increased tissue demands
• RBCs which have reduced oxygen carrying capacity

Question 2

List the functions of erythropoietin

Answer 2

• Stimulating bone marrow cells which are committed to becoming RBCs

Question 3

Describe how chronic renal failure affects the release of erythropoietin and what the consequence of this is

Answer 3

Chronic renal failure leads to scarring which causes a decrease in functioning cells and a drop of erythropoetin. As a consequence there is a reduced capacity of the blood to carry oxygen. Patient presents with lethargy as a result of anaemia.

Question 4

Describe how low levels of erythropoietin are treated in chronic renal failure

Answer 4

Synthetic erythropoietin

Question 5

List the main actions of calcitriol (1,25-dihydroxycholecalciferol)

Answer 5

• Stimulate the absorption of ingested calcium via increasing the expression of calcium channels.
• This results in increased phosphate absorption

Question 6

Describe the effects of chronic renal failure on calcitriol production

Answer 6

It is reduced which can lead to hyperparathyroidism (due to reduced circulating calcium levels stimulating growth of the gland), osteomalacia and osteoporosis.