PTH should be measured only if which condition is present?

PTH should be measured only if which condition is present?

• A. CALCIUM IS ELEVATED
• B. CALCIUM IS LOW
• C. MAGNESIUM IS ELEVATED
• D. RAN CAN BE CHECKED

Answer: (A)

Measuring PTH is most informative when calcium levels are elevated because it helps determine whether the high calcium is due to excess parathyroid hormone or another cause. If calcium is high and PTH is inappropriately normal or elevated, this points to a PTH-mediated hypercalcemia (such as primary hyperparathyroidism). If calcium is high and PTH is appropriately suppressed, the hypercalcemia is due to non-PTH mechanisms like malignancy, vitamin D excess, or other factors. This distinction guides subsequent management. While PTH can also be useful in evaluating low calcium, the scenario described focuses on hypercalcemia, where PTH measurement most directly informs the cause.

Measuring PTH is most informative when calcium levels are elevated because it helps determine whether the high calcium is due to excess parathyroid hormone or another cause. If calcium is high and PTH is inappropriately normal or elevated, this points to a PTH-mediated hypercalcemia (such as primary hyperparathyroidism). If calcium is high and PTH is appropriately suppressed, the hypercalcemia is due to non-PTH mechanisms like malignancy, vitamin D excess, or other factors. This distinction guides subsequent management. While PTH can also be useful in evaluating low calcium, the scenario described focuses on hypercalcemia, where PTH measurement most directly informs the cause.