Citrate Excretion, Urine
NY State Approved Indicates the status of NY State approval and if the test is orderable for NY State clients.
Diagnosing risk factors for patients with calcium kidney stones
Monitoring results of therapy in patients with calcium stones or renal tubular acidosis
Special Instructions and Forms Describes specimen collection and preparation information, test algorithms, and other information pertinent to test. Also includes pertinent information and consent forms to be used when requesting a particular test
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
Citrate Excretion, U
Citric Acid, Urine
Urinary Citrate Excretion
Urinary Citrate Excretion
Specimen Type Describes the specimen type needed for testing
Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.
Container/Tube: Plastic, 6-mL tube (Supply T465)
Specimen Volume: 5 mL
1. Collect urine for 24 hours.
2. Add 10 g of boric acid as preservative at start of collection.
3. Any drug that causes alkalemia or acidemia may be expected to alter citrate excretion and should be avoided, if possible.
4. Mix well before taking 5-mL aliquot.
1. Patient's age and 24-hour volume are required.
2. See Urine Preservatives in Special Instructions for multiple collections.
Urine Preservative Collection Options
50% Acetic Acid
Specimen Minimum Volume Defines the amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
|Urine||Refrigerated (preferred)||7 days|
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Urinary citrate is a major inhibitor of kidney stone formation due in part to binding of calcium in urine. Low urine citrate levels are considered a risk for kidney stone formation.
Several metabolic disorders are associated with low urine citrate. Any condition which lowers renal tubular pH or intracellular pH may decrease citrate, (eg, metabolic acidosis, increased acid ingestion, hypokalemia, or hypomagnesemia).
Low urinary citrate promotes kidney stone formation and growth, and is subject to therapy by correcting acidosis, hypokalemia, or hypomagnesemia by altering diet or using drugs such as citrate and potassium.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
0-19 years: not established
20 years: 150-1,191 mg/specimen
21 years: 157-1,191 mg/specimen
22 years: 164-1,191 mg/specimen
23 years: 171-1,191 mg/specimen
24 years: 178-1,191 mg/specimen
25 years: 186-1,191 mg/specimen
26 years: 193-1,191 mg/specimen
27 years: 200-1,191 mg/specimen
28 years: 207-1,191 mg/specimen
29 years: 214-1,191 mg/specimen
30 years: 221-1,191 mg/specimen
31 years: 228-1,191 mg/specimen
32 years: 235-1,191 mg/specimen
33 years: 242-1,191 mg/specimen
34 years: 250-1,191 mg/specimen
35 years: 257-1,191 mg/specimen
36 years: 264-1,191 mg/specimen
37 years: 271-1,191 mg/specimen
38 years: 278-1,191 mg/specimen
39 years: 285-1,191 mg/specimen
40 years: 292-1,191 mg/specimen
41 years: 299-1,191 mg/specimen
42 years: 306-1,191 mg/specimen
43 years: 314-1,191 mg/specimen
44 years: 321-1,191 mg/specimen
45 years: 328-1,191 mg/specimen
46 years: 335-1,191 mg/specimen
47 years: 342-1,191 mg/specimen
48 years: 349-1,191 mg/specimen
49 years: 356-1,191 mg/specimen
50 years: 363-1,191 mg/specimen
51 years: 370-1,191 mg/specimen
52 years: 378-1,191 mg/specimen
53 years: 385-1,191 mg/specimen
54 years: 392-1,191 mg/specimen
55 years: 399-1,191 mg/specimen
56 years: 406-1,191 mg/specimen
57 years: 413-1,191 mg/specimen
58 years: 420-1,191 mg/specimen
59 years: 427-1,191 mg/specimen
60 years: 434-1,191 mg/specimen
>60 years: not established
Any value less than the mean for 24 hours represents a potential risk for kidney stone formation/growth. Patients with low urinary citrate, and new or growing stone formation may benefit from adjustments in therapy known to increase urinary citrate excretion. (See Clinical Information).
Very low levels (<150 mg/24 hours) suggest investigation for the possible diagnosis of metabolic acidosis (eg, renal tubular acidosis).
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
Drugs that lower systemic pH, potassium, and/or magnesium lower urine citrate and are to be avoided in patients with tendency to calcium stones.
Conversely, drugs that raise systemic pH, potassium, and/or magnesium may raise urine citrate and should be considered in treating patients or interpreting results.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
Hosking DH, Wilson JW, Liedtke RR, et al: The urinary excretion of citrate in normal persons and patients with idiopathic calcium urolithiasis (abstract). Urol Res 1984;12:26
Method Description Describes how the test is performed and provides a method-specific reference
Citric acid in the presence of Zn(++) at pH 8.2 is catalyzed to oxaloacetate by the enzyme, citrate lyase. Oxaloacetate in the presence of malate dehydrogenase and reduced nicotinamide adenine dinucleotide (NADH) is reduced to malate (II). By measuring the disappearance of the light-absorbing NADH, the citric acid concentration in the reaction mixture can be determined. By correcting this concentration for dilution and 24-hour volume, the amount of citric acid excreted per 24 hours is obtained.(Nielsen TT: A method for enzymatic determination of citrate in serum and urine. Scand J Clin Lab Invest 1976;36:513-519)
Supplemental Report Indicates whether the report includes an additional document with charts, images or other enriched information
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Monday through Saturday; 8 a.m.-4 p.m.
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
Same day/1 day
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location The location of the laboratory that performs the test
Test Classification Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer's instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR), Investigation Use Only (IUO) product, or a Research Use Only (RUO) product.
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.
CPT Code Information Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Medical Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
LOINC® Code Information Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the result codes returned for this test or profile.
|Result ID||Reporting Name||LOINC Code|
|CITRT||Citrate Excretion, U||6687-8|