MEq

MEq

The term MEq stands for Milliequivalent, a unit of measurement used in chemistry and medicine to express the amount of a substance based on its chemical activity or combining power. It is particularly useful in the context of electrolytes, where it helps quantify the concentration of ions in a solution.

Definition

A milliequivalent (mEq) is one-thousandth of an equivalent (Eq), which is a measure of the reactive capacity of a molecule. The concept of equivalents is based on the amount of a substance that will react with or supply one mole of hydrogen ions (H⁺) in an acid-base reaction, or one mole of electrons in a redox reaction.

Calculation

The calculation of milliequivalents involves the following steps:

1. Determine the molecular weight (MW) of the substance. 2. Identify the valence (n), which is the number of moles of charge that one mole of the substance can donate or accept. 3. Calculate the equivalent weight (EW) using the formula:

  \[
  \text{Equivalent Weight (EW)} = \frac{\text{Molecular Weight (MW)}}{\text{Valence (n)}}
  \]

4. Convert to milliequivalents by dividing the amount of substance in milligrams by the equivalent weight and multiplying by 1000:

  \[
  \text{mEq} = \frac{\text{mg of substance}}{\text{EW}} \times 1000
  \]

Applications in Medicine

In medicine, milliequivalents are commonly used to express the concentration of electrolytes in biological fluids. Electrolytes such as sodium (Na⁺), potassium (K⁺), calcium (Ca²⁺), and chloride (Cl⁻) are vital for maintaining cellular function and fluid balance.

Electrolyte Balance

Electrolyte balance is crucial for normal physiological function. Imbalances can lead to conditions such as:

• Hyponatremia: Low sodium levels.
• Hyperkalemia: High potassium levels.
• Hypocalcemia: Low calcium levels.

Intravenous Solutions

Intravenous (IV) solutions are often formulated based on milliequivalents to ensure the correct balance of electrolytes is administered to patients. For example, a common IV solution might contain 154 mEq/L of sodium chloride.

Also see

• Electrolyte
• Acid-base balance
• Intravenous therapy
• Molecular weight

References

• "Clinical Chemistry: Principles, Techniques, and Correlations" by Michael L. Bishop, Edward P. Fody, and Larry E. Schoeff.
• "Medical Physiology: A Systems Approach" by Hershel Raff and Michael Levitzky.

Resources

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Source: Data courtesy of the U.S. National Library of Medicine. Since the data might have changed, please query MeSH on MEq for any updates.

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