**Core Concept:** Pseudohyponatremia is a laboratory phenomenon characterized by elevated serum sodium levels despite abnormalities in osmolality or protein concentration. This can occur due to increased osmotically inactive substances like triglycerides, phospholipids, or advanced glycosylation end-products (AGEs).

**Why the Correct Answer is Right:** The correct answer is C (elevated triglycerides). Pseudohyponatremia arises from the presence of osmotically inactive substances like triglycerides, which dilute the osmolality of the serum, causing an apparent elevation of sodium levels.

**Why Each Wrong Option is Incorrect:**

A. Hyponatremia (low serum sodium levels) is the opposite of pseudohyponatremia and does not result from elevated triglycerides.
B. Hypernatremia (low serum sodium levels) does not result from elevated triglycerides.
D. Hyperlipidemia, while associated with elevated triglycerides, does not directly cause pseudohyponatremia.

**Clinical Pearl / High-Yield Fact:** A clinical pearl to remember pseudohyponatremia is "PEGs" - elevated triglycerides, glucose, electrophoresis, and AGEs. This mnemonic aids in identifying conditions that can cause pseudohyponatremia, ensuring accurate interpretation of serum sodium levels in clinical practice.