Effect of steroids on calcium
**Core Concept**
Glucocorticoids, a class of steroids, have a complex effect on calcium metabolism, influencing bone resorption, bone formation, and mineral ion homeostasis.
**Why the Correct Answer is Right**
Glucocorticoids increase bone resorption by stimulating the activity of osteoclasts, which are responsible for breaking down bone tissue. This leads to an increase in the release of calcium into the bloodstream. Additionally, glucocorticoids decrease the expression of osteocalcin, a protein involved in bone mineralization, further contributing to the negative effect on bone formation. The resulting increase in serum calcium levels can lead to hypercalcemia.
**Why Each Wrong Option is Incorrect**
**Option A:** This option would be incorrect if it stated a decrease in bone resorption or an increase in bone formation, as glucocorticoids have the opposite effects.
**Option B:** This option would be incorrect if it mentioned an increase in parathyroid hormone (PTH) levels, as glucocorticoids actually decrease PTH levels.
**Option C:** This option would be incorrect if it stated a decrease in serum calcium levels, as glucocorticoids typically lead to an increase in serum calcium levels.
**Clinical Pearl / High-Yield Fact**
Glucocorticoids can lead to osteoporosis, a condition characterized by a decrease in bone mass and density, which increases the risk of fractures. This is particularly relevant in patients with chronic glucocorticoid therapy, such as those with asthma or rheumatoid arthritis.
**Correct Answer: B. Glucocorticoids increase bone resorption and decrease bone formation, leading to an increase in serum calcium levels.**