Home :: Sodium And Chloride Test

Sodium And Chloride - Deficiency Test

The sodium and chloride test determines urine levels of sodium, the major extracellular cation, and of chloride, the major extracellular anion. Less significant than serum levels (and, consequently, performed less frequently), measurement of urine sodium and urine chloride concentrations is used to evaluate renal conservation of these two electrolytes and to confirm serum sodium and chloride values.

In the body, sodium and chloride help maintain osmotic pressure and water and acid-base balance. Normal ranges of sodium and chloride in the urine vary greatly with dietary salt intake and perspiration.

Purpose

• To help evaluate fluid and electrolyte imbalance
• To monitor the effects of a low-salt diet
• To help evaluate renal and adrenal disorders

Patient preparation

• Explain to the patient that this test helps determine the balance of salt and water in the body.
• Advise him that no special restrictions are necessary.
• Tell him the test requires urine collection over a 24-hour period.
• If the specimen is to be collected at home, instruct the patient on proper collection technique.

Procedure and posttest care

• Collect the patient's urine over a 24hour period.

Precautions

• Tell the patient not to contaminate the specimen with toilet tissue or stool.

Reference values

Normal urine sodium excretion ranges from 40 to 220 mEq/L/24 hours or 40 to 220 mmol/day in an adult; in a child, from 41 to 115 mEq/L/24 hours. Normal urine chloride excretion ranges from 140 to 250 mEq/L/24 hours in an adult; in children ages 6 to 10, from 15 to 40 mEq/L/24 hours; and in children ages to to 14, from 64 to 176 mEq/L/ 24 hours.

Abnormal findings

Usually, urine sodium and urine chloride levels are parallel, rising and falling in tandem. Abnormal levels of both minerals may indicate the need for more specific testing.

Elevated urine sodium levels may reflect increased salt intake, adrenal failure, salicylate toxicity, diabetic acidosis, salt-losing nephritis, and water-deficient dehydration.

Decreased urine sodium levels suggest decreased salt intake, primary aldosteronism, acute renal failure, and heart failure.

Elevated urine chloride levels may result from water-deficient dehydration, salicylate toxicity, diabetic ketoacidosis, adrenocortical insufficiency (Addison's disease), or salt-losing renal disease. Decreased levels may result from excessive diaphoresis, heart failure, hypochloremic metabolic alkalosis, or prolonged vomiting or gastric suctioning.

To evaluate fluid-electrolyte imbalance, results must be correlated with findings of serum electrolyte studies.

Interfering factors

• Contamination of the specimen with toilet tissue or stool
• Caffeine, diuretics, dopamine, postmenopausal diuresis, and increased sodium intake (possible increase in sodium)
• Corticosteroids, epinephrines, propranolol, low sodium intake, premenstrual sodium and water retention, and stress diuresis (possible decrease in sodium)
• Carbenicillin therapy, reduced chloride intake, ingestion of large amounts of licorice, alkali ingestion (possible decrease in chloride)
• Ammonium chloride administration, excessive infusion of normal saline solution, sulfides, cyanides, halogens, and bromides (possible increase in chloride)