Which deficiency leads to symptoms such as hypocalcemia, tetany, and tachycardia?

The deficiency that leads to symptoms such as hypocalcemia, tetany, and tachycardia is magnesium deficiency. Magnesium plays a critical role in various physiological processes, including the regulation of calcium levels within the body. When magnesium levels are low, it can disrupt calcium homeostasis.

Hypocalcemia, or low calcium levels, occurs because magnesium is essential for the secretion of parathyroid hormone (PTH), which regulates calcium levels in the blood. Without sufficient magnesium, the body may respond inadequately to the presence of low calcium, leading to tetany—a condition characterized by muscle spasms and cramps due to increased neuromuscular excitability. Tachycardia, or an increased heart rate, may also occur as a result of the body's compensatory mechanisms responding to electrolyte imbalances.

Understanding the role of magnesium in calcium metabolism is crucial for recognizing how its deficiency can lead to these specific symptoms, distinguishing it from deficiencies in potassium, sodium, and calcium itself.