24 Hour Urine Chloride
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Contents |
Indications
- evaluation of acid-base disorders
- evaluation of hypokalemia
- diagnosis of renal tubular acidosis
Reference-interval
- 110-250 mEq/24 hours
Principle
- Chloride is the major extracellular anion. Most ingested chloride is absorbed, & the excess is excreted in the urine.
- Chloride reacts with mercuric thiocyanate. The thiocyanate thus released reacts with ferric ion & forms a red ferric thiocyanate complex. The absorbance due to this complex is directly proportional to the chloride concentration in the sample & is measured using a two-filter (452-600 nm) endpoint technique.
Clinical-significance
- Urine chloride levels are strongly dependent on dietary intake. The measurement of urinary chloride is of clinical value only in patients with persistent metabolic alkalosis who are not receiving diuretic.
Increases
- increased salt intake
- postmenopausal diuresis
- massive diuresis
- salt-losing nephritis
Decreases
- reduced salt intake
- premenstrual salt & water retention
- hypochloremia
- adrenal hyperplasia
- postoperative chloride retention
- other forms of salt retention
Specimen
- 2 mL aliquot of a 24-hour urine collection. Proper 24 hour urine collection procedure should be followed, & collection container should be refrigerated at 2-6 C during collection. The 24-hour urine collection is well-mixed & then measured in a graduated cylinder. The total volume should be recorded.
More General Terms
References
- Kaplan, Lawrence A. & Pesce, Amadeo J., Clinical Chemistry: Theory, Analysis, & Correlation, 2nd Edition, The C.V. Mosby Company, St. Louis, MO, 1989, pp.357, 874-875.
- Henry, John Bernard, M.D., Clinical Diagnosis & Management by Laboratory Methods, 18th Edition, W.B. Saunders Company, Philadelphia, PA, 1991, pp. 131-132.
- ACA IV Discrete Clinical Chemistry Analyzer Instrument Manual, Volume 3A, Chapter 6: Test Methodology, CL 17
- Medline Plus: Chloride -urine [1]
