Renal - Kidneys And Bone

Question 1

Vitamin D is activated by _________ enzyme into ________. This active form is responsible for _______ of Calcium and ________ of phosphate in the small intestines.

Answer 1

1-alpha hydroxylase helps activate Vitamin D into Calcitriol. The active form causes absorption of dietary Ca++ and PO4 in the gut.

Question 2

What is PTH’s effect on phosphate and calcium in the kidney?

Answer 2

PTH causes reabsorption of Ca++ and a more powerful effect of phosphate wasting than Calcitriol’s reabsorptive effect.

Question 3

List 3 factors that inhibit the activity of 1-alpha hydroxylase in its function for activating Vitamin D.

Answer 3

Elevated Plasma Ca++, Elevated Phosphate levels, High Calcitriol levels

Question 4

Describe the cause and effects of Hypoparathyroidism.

Answer 4

Caused by an issue with parathyroid glands or their removal (such as through thyroid surgery). This is presented as Hypocalcemia, Hyperphosphatemia (due to a lack of PTH) and Hypocalciuria (since there is no calcium movement from bone to start with).

Question 5

Describe the cause and effects of Secondary Hyperparathyroidism.

Answer 5

Diseased kidneys cannot respond to PTH, but bone still does react to this hormone. This results in Hypocalcemia (since bone is resorbed BUT calcification occurs at joints and heart valves) and Hyperphosphatemia (marked by the bone resorption) Osteoporosis may be indicated on an X-ray and Ca++ in vasculature/joints.