Hypercalcemia And Hypocalcemia! Quiz

1. A 40-year-old man is seen as a new patient to establish care. He has no complaints. His past medical history is negative. Baseline laboratory studies are significant for serum calcium of 11.5 mg/dL. Physical examination is normal. In the above scenario, would this patient's parathyroid hormone level be:

High

Normal

Low

Based on the scenario provided, the patient's serum calcium level is high at 11.5 mg/dL. In a normal physiological response, the parathyroid hormone (PTH) level would be expected to be low to help bring down the elevated calcium level. However, since the answer is stated as "high," it suggests that the patient's PTH level is elevated. This could indicate primary hyperparathyroidism, a condition where the parathyroid glands produce excessive PTH, leading to increased calcium levels in the blood.

Explanation

Based on the scenario provided, the patient's serum calcium level is high at 11.5 mg/dL. In a normal physiological response, the parathyroid hormone (PTH) level would be expected to be low to help bring down the elevated calcium level. However, since the answer is stated as "high," it suggests that the patient's PTH level is elevated. This could indicate primary hyperparathyroidism, a condition where the parathyroid glands produce excessive PTH, leading to increased calcium levels in the blood.

2. A 40-year-old man is seen as a new patient to establish care. He has no complaints. His past medical history is negative. Baseline laboratory studies are significant for serum calcium of 11.5 mg/dL. Physical examination is normal. This patient's phosphate level would be:

High

Normal

Low

The patient's serum calcium level is elevated, which suggests hypercalcemia. In cases of hypercalcemia, there is often a reciprocal decrease in serum phosphate levels. Therefore, the patient's phosphate level would be low.

Explanation

The patient's serum calcium level is elevated, which suggests hypercalcemia. In cases of hypercalcemia, there is often a reciprocal decrease in serum phosphate levels. Therefore, the patient's phosphate level would be low.

3. In response to a sudden decrease in plasma calcium, where do most of the calcium come from to restore plasma levels?

The renal tubues

Bone

The GI tract

In response to a sudden decrease in plasma calcium, most of the calcium comes from the bone to restore plasma levels. This is because bone serves as a reservoir for calcium, and it can release calcium into the bloodstream when necessary. The process of releasing calcium from the bone is regulated by hormones such as parathyroid hormone (PTH) and calcitonin. These hormones help maintain calcium homeostasis by stimulating bone resorption (breaking down of bone) or bone deposition (formation of new bone) respectively. Therefore, the bone is the primary source of calcium during a sudden decrease in plasma levels.

Explanation

In response to a sudden decrease in plasma calcium, most of the calcium comes from the bone to restore plasma levels. This is because bone serves as a reservoir for calcium, and it can release calcium into the bloodstream when necessary. The process of releasing calcium from the bone is regulated by hormones such as parathyroid hormone (PTH) and calcitonin. These hormones help maintain calcium homeostasis by stimulating bone resorption (breaking down of bone) or bone deposition (formation of new bone) respectively. Therefore, the bone is the primary source of calcium during a sudden decrease in plasma levels.

4. The most important action of vitamin D is to stimulate:

Calcium deposition in bone

Calcium resorption from bone

Calcium absorption from the GI tract

Calcium resorption in the renal tubule

The answer is C. Vitamin D probably acts in a permissive manner for all of these processes, but stimulation of calcium absorption from the GI tract is the most important direct action.

Explanation

The answer is C. Vitamin D probably acts in a permissive manner for all of these processes, but stimulation of calcium absorption from the GI tract is the most important direct action.

5. Chronic failure of the kidneys leads to what problem?

High plasma parathyroid hormone

Low plasma phosphate

Inability to transfer calcium from bone to the blood

High plasma vitamin D

The answer is A. Chronic renal failure reduces phosphate excretion. As a consequence, levels of PTH increase, causing excessive resorption of calcium from bone.

Explanation

The answer is A. Chronic renal failure reduces phosphate excretion. As a consequence, levels of PTH increase, causing excessive resorption of calcium from bone.

6. Parathyroid hormone stimulates phosphate secretion in the proximal tubule. True or false.

True

False

The answer is false. PTH inhibits phosphate reabsorption, resulting in increased excretion. The increased excretion is the same result that would occur if secretion were increased, but phosphate is not secreted.

Explanation

The answer is false. PTH inhibits phosphate reabsorption, resulting in increased excretion. The increased excretion is the same result that would occur if secretion were increased, but phosphate is not secreted.

7. When a reduction in parathyroid hormone stimulates the kidneys to increase excretion of calcium, they do so by what mechanism?

Increased glomerular filtration

Reduced absorption in the proximal tubule

Increased secretion in the distal tubules

Increased reabsorption in distal tubule

The answer is D. PTH stimulates calcium reabsorption in the distal tubule; thus, a reduction in PTH reduces reabsorption and permits more excretion.

Explanation

The answer is D. PTH stimulates calcium reabsorption in the distal tubule; thus, a reduction in PTH reduces reabsorption and permits more excretion.