Which calcium value would best support the diagnosis of parathyroid dysfunction as described in the clinical scenario?

Which calcium value would best support the diagnosis of parathyroid dysfunction as described in the clinical scenario?

• A. 7.8 mg/dL
• B. 8.9 mg/dL
• C. 9.7 mg/dL
• D. 10.2 mg/dL

Answer: (A)

Calcium levels are tightly controlled by parathyroid hormone (PTH). When the parathyroids aren’t functioning well, calcium in the blood can drop because PTH isn’t promoting bone breakdown, kidney calcium reabsorption, and activation of vitamin D to boost intestinal absorption. A calcium value of 7.8 mg/dL is clearly below the normal range (roughly 8.5–10.5 mg/dL) and fits with hypoparathyroidism or other parathyroid dysfunction. This low calcium can explain symptoms like tingling, muscle cramps, or tetany that clinicians look for in parathyroid disorders.

The other values are within or near the normal range and don’t point as strongly to parathyroid dysfunction. So the low calcium value best supports the diagnosis in this context.