Hormones that help regulate blood calcium levels are produced by the

1. Analyze the question The question asks which gland produces hormones that regulate calcium levels in the blood.

2. Explain the concept Blood calcium is controlled mainly by two hormones:

• Parathyroid hormone (PTH), produced by the parathyroid glands. It raises blood calcium by releasing calcium from bones, increasing absorption in the kidneys, and activating vitamin D to boost absorption in the intestines.
• Calcitonin, produced by the thyroid gland (the parafollicular cells). It lowers blood calcium by promoting calcium deposition in bones.

The parathyroid glands are four tiny glands embedded at the back of the thyroid gland in the neck. The parathyroid is the principal regulator of calcium balance.

3. Solution: checking each option

• A. Adrenal: Produces adrenaline, cortisol and aldosterone. These deal with stress response, metabolism and salt balance, not calcium. ❌
• B. Thyroid: Produces thyroxine (metabolic rate) and calcitonin (which does lower calcium). This is partly relevant, but the thyroid's main role is metabolism. ❌ (not the best answer)
• C. Pancreas: Produces insulin and glucagon, which regulate blood sugar. ❌
• D. Parathyroid: Produces PTH, the key hormone regulating blood calcium. ✅

4. Answer **D. Parathyroid.

5. Exam tip Remember the link between the names: PARA-thyroid → CALCIUM. In JAMB, when a question asks about calcium regulation, think "parathyroid" first. Also remember that low calcium causes tetany (muscle spasms), a classic sign of parathyroid deficiency.