To Estimate Sodium and Potassium in Serum by Using Flame Photometer
Sodium is the major cation of extracellular fluid. Sodium is important for the maintenance of osmotic pressure, fluid balance, and acid-base regulation. The sodium is lost from the body via excretion through kidneys and excessive sweating. About 50% of body sodium is present in bones followed by 40% in extracellular fluid and 10% in soft tissues. Both extracellular and intracellular sodium are the exchangeable form of sodium. The intracellular sodium contributes about 10 mmol/L, and the extracellular form contributes about 135–145 mmol/L. Sodium is also involved in normal muscle irritability, cell permeability, and maintenance of heartbeat. In contrast to sodium, potassium is present mainly in intracellular fluid. It is present majorly in RBCs (23 times higher than plasma). Like sodium, excess potassium is also excreted by kidneys. Normal potassium concentration in plasma is in range of 3.5–5.5 mEq/L. It is necessary for regulation of intracellular osmotic pressure, water balance in cells, transmission of nerve impulse, etc.