Calcium Excretion, 2-Hour Collection, Fasting, Urine
NY State Approved Indicates the status of NY State approval and if the test is orderable for NY State clients.
Differentiating absorptive from nonabsorptive causes of hypercalciuria
Profile Information A profile is a group of laboratory tests that are ordered and performed together under a single Mayo Test ID. Profile information lists the test performed, inclusive of the test fee, when a profile is ordered and includes reporting names and individual availability.
|Test ID||Reporting Name||Available Separately||Always Performed|
|2HCA||Calcium Excretion, Fast, 2 Hr, U||No||Yes|
|CAU2||Calcium, U||Yes, (order CAU)||Yes|
Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES)
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
Calcium Excretion, Fast, 2 Hr, U
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.
Collection Container/Tube: Plastic urine container
Submission Container/Tube: Plastic, 6-mL tube (Supply T465)
Specimen Volume: 5 mL
1. Collect a 2-hour urine specimen.
2. Add 2 mL of 6N HCl as preservative at start of collection.
3. Instructions for 2-hour urine collection are as follows:
a. No food or drink after 6 p.m. the evening before the test (except as indicated by physician).
b. On the day of the test, do not void after 8 a.m.
c. At precisely 10 a.m., void (empty bladder). Discard urine.
d. Drink 2 glasses of water (1 at 10 a.m. and 1 at 11 a.m.). This must be deionized or distilled water.
e. Void (empty bladder) precisely at 12 noon.
f. Save all of urine voided at 12 noon in container provided.
Additional Information: 2-Hour volume is required.
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||Frozen (preferred)||7 days|
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Urine calcium is a reflection of dietary intake, bone turnover, and renal excretion mechanisms. At steady-state excretion is usually approximately 30% of the dietary intake.
Patients with renal lithiasis often (35%) have increased urine calcium which may reflect an increased intake or an abnormality in the above mechanisms.
Therapy for hypercalciuria depends on the cause. Increased calcium in diet or increased gastrointestinal absorption usually responds to dietary restriction while hypercalciuria from other mechanisms usually responds to thiazides. Diet restriction is contraindicated in the nonabsorptive groups and thiazides are usually unnecessary or ineffective in the former group.
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.
Absorptive hypercalciuria: <20 mg calcium/2-hour specimen or a calcium/creatinine ratio of <0.15
Nonabsorptive hypercalciuria: >30 mg calcium/2-hour specimen or a calcium/creatinine ratio of >0.15
Indeterminate: 20-30 mg calcium/2-hour specimen
If a patient is hypercalciuric and on a 1 g calcium diet, urine calcium results from a 2-hour urine specimen after 14 hours of fasting:
Cause for hypercalciuria
<20 mg/2-hour specimen or
<0.15 calcium/creatinine ratio
Increased gut absorption
>30 mg/2-hour specimen or
Nephrogenic or metabolic indeterminate
20 mg/2 hour to 30 mg/2-hour specimen
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
Hypercalciuria is markedly dependent on sodium excretion and results may be altered if very low or high sodium diets are allowed.
Patients should drink distilled or deionized water during the test.
Exact timing and volume measurement are essential.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
Pak CY, Oata M, Lawrence EC, Snyder W: The hypercalciurias. Causes, parathyroid functions, and diagnostic criteria. J Clin Invest 1974;54:387-400
Method Description Describes how the test is performed and provides a method-specific reference
Calcium is determined by inductively coupled plasma-atomic emission spectroscopy (ICP-AES). (Nixon DE, Moyer TP, Johnson P, et al: Routine measurement of calcium, magnesium, copper, zinc, and iron in urine and serum by inductively coupled plasma emission spectroscopy. Clin Chem 1986;32:1660-1665)
Creatinine is determined by an enzymatic method based on the determination of sarcosine from creatinine with the aid of creatininase, creatinase, and sarcosine oxidase. The liberated hydrogen peroxide is measured via a modified Trinder reaction using a colorimetric indicator. Optimization of the buffer system and the colorimetric indicator enables the creatinine concentration to be quantified both precisely and specifically. (Package insert: Roche Diagnostics, Indianapolis IN, 2004)
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 Friday; 12 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
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|
|9331||Calcium Excretion, Fast, 2 Hr, U||16518-3|