Sodium, urine

Alternate test name

Sodium Urine

Lab area

Clinical Biochemistry - General

Method and equipment

Equipment : Roche Cobas Pro ISE

Method : Test principle An Ion‑Selective Electrode (ISE) makes use of the unique properties of ion‑selective membrane to develop an electrical potential (electromotive force, EMF) for the measurements of ions in solution. Selective membrane is in contact with both the test solution and an internal filling solution. Due to the selectivity of the membrane, only the ions to be measured contribute to the EMF. The membrane EMF is determined by the difference in concentration of the test ion in the test solution and the internal filling solution. The EMF develops according to the Nernst equation for a specific ion in solution The complete measurement system for a particular ion includes the ISE, a reference electrode and electronic circuits to measure and process the EMF to give the test ion concentration. The sodium2,3 and potassium4 electrodes are based on neutral carriers and the chloride5 electrode is based on an ion exchanger

Expected turn-around time

Random Urine STAT/ Urgent: 4 Hours Routine: 24 Hours Timed Urine STAT/Urgent/Routine: 24 Hours

Shipping information

Background and clinical significance

The ISE analytical unit of the cobas c systems is intended for the quantitative determination of sodium, potassium and chloride in serum, plasma or urine using ion‑selective electrodes. Sodium measurements are used in the diagnosis and treatment of aldosteronism (excessive secretion of the hormone aldosterone), diabetes insipidus (chronic excretion of large amounts of dilute urine, accompanied by extreme thirst), adrenal hypertension, Addison's disease (caused by destruction of the adrenal glands), dehydration, inappropriate antidiuretic hormone secretion, or other diseases involving electrolyte imbalance. Physiological significance: Electrolytes are involved in most major metabolic functions in the body. Sodium and potassium are amongst the most important physiological ions and the most often assayed electrolytes. They are supplied primarily through the diet, absorbed in the gastrointestinal tract, and excreted via the kidneys. Sodium is the major extracellular cation and functions to maintain fluid distribution and osmotic pressure. Some causes of decreased levels of sodium include prolonged vomiting or diarrhea, diminished reabsorption in the kidney and excessive fluid retention. Common causes of increased sodium include excessive fluid loss, high salt intake and increased kidney reabsorption.