MeqL

mEq/L stands for milliequivalents per liter and is a unit used to express the concentration of ions in solution in terms of the electrical charge they carry. It reflects both amount of substance and valence, making it common in clinical chemistry and fluid therapy to describe electrolytes.

Calculation can be done from molar concentration or mass concentration. For ions in solution, mEq/L = mmol/L × valence. For example, sodium (Na+) with valence +1: 1 mmol/L Na+ equals 1 mEq/L. Calcium (Ca2+) with valence +2: 1 mmol/L Ca2+ equals 2 mEq/L. If a concentration is given as mg/L, mEq/L = (mg/L) / (equivalent weight), where equivalent weight = molar mass divided by the valence. For Ca2+ (molar mass ~40 g/mol, valence 2), 1 mg/L corresponds to about 0.05 mEq/L.

In medical practice, mEq/L is used to report electrolyte levels in blood and in IV solutions. Common ions and typical clinical ranges include sodium about 135–145 mEq/L, potassium about 3.5–5.0 mEq/L, chloride about 95–105 mEq/L, and calcium total around 2.2–2.6 mEq/L. Normal saline, a widely used IV fluid, contains about 154 mEq/L each of Na+ and Cl−, illustrating how the unit communicates charge balance.

Notes and considerations include that mEq/L is not an SI unit, but is widely accepted in clinical settings. For monovalent ions, mEq/L roughly equals mmol/L; for multivalent ions, mEq/L differs by the ion’s valence. Interpreting results requires context, including the specific lab method and patient condition.