[Campbell Biology P.1060] A patient is found to have significantly low blood calcium levels d... | Practice Question

A patient is found to have significantly low blood calcium levels despite adequate dietary calcium intake. Which of the following conditions, based on Figure 45.18 and the accompanying text, could explain this observation?

  • A: Overproduction of Parathyroid Hormone (PTH).
  • B: Impaired function of the parathyroid glands.
  • C: Excessive absorption of Ca2+ in the intestines.
  • D: A higher-than-normal set point for blood Ca2+ regulation.

Explanation

The parathyroid glands release PTH when blood Ca2+ levels fall. PTH is crucial for raising Ca2+ levels by acting on bones, kidneys, and intestines via vitamin D . If these glands are impaired, insufficient PTH would be released, leading to persistently low blood calcium, even with adequate dietary intake.