**Core Concept**
Hydrofluoric acid poisoning is a serious condition that affects various bodily systems, particularly the cardiovascular and nervous systems, due to its ability to interfere with cellular functions. The **fluoride ion** is the key toxic component, causing severe **hypocalcemia** and **hyperkalemia** by disrupting cellular membrane functions and interfering with ion channels.

**Why the Correct Answer is Right**
In hydrofluoric acid poisoning, the fluoride ions bind to calcium ions, forming insoluble **calcium fluoride**, which leads to a significant drop in serum calcium levels (**hypocalcemia**). Additionally, the poisoning can cause **hyperkalemia** due to cellular damage and release of potassium ions. However, the question is about which electrolyte abnormality is not seen, implying we are looking for an option that does not typically result from hydrofluoric acid exposure.

**Why Each Wrong Option is Incorrect**
**Option A:** Hypocalcemia is incorrect because it is indeed seen in hydrofluoric acid poisoning due to the formation of calcium fluoride.
**Option B:** Hyperkalemia is also incorrect as it can occur due to cellular damage.
**Option C:** Hyponatremia might not be directly related to the primary effects of hydrofluoric acid poisoning, which are more closely associated with calcium and potassium imbalances.

**Clinical Pearl / High-Yield Fact**
A critical point to remember is that hydrofluoric acid poisoning can lead to severe and potentially fatal **hypocalcemia** and **cardiac arrhythmias** due to the fluoride ion's effect on cellular and ion channel functions. Prompt treatment with calcium gluconate is essential.

**Correct Answer:** D. Hyponatremia is not typically seen as a direct result of hydrofluoric acid poisoning.