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Test Code U24 Citrate Citrate Excretion, 24 Hour, Urine

Reporting Name

Citrate Excretion, U

Useful For

Diagnosing risk factors for patients with calcium kidney stones

 

Monitoring results of therapy in patients with calcium stones or renal tubular acidosis


Specimen Required


Container/Tube: Plastic, 5-mL tube (T465)

Specimen Volume: 4 mL

Collection Instructions:

1. Add 30 mL of toluene as preservative at start of collection or refrigerate specimen during and after collection.

2. Collect urine for 24 hours.

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 4-mL aliquot.

Additional Information:

1. Patient's age and 24-hour volume are required.

2. See Urine Preservatives-Collection and Transportation for 24-Hour Urine Specimens in Special Instructions for multiple collections.


Specimen Type

Urine

Specimen Minimum Volume

1 mL

Specimen Stability Information

Specimen Type Temperature Time
Urine Refrigerated (preferred) 14 days
  Frozen  14 days

Day(s) and Time(s) Performed

Monday through Saturday; 8 a.m.-4 p.m.

Performing Laboratory

Mayo Medical Laboratories in Rochester

Method Name

Enzymatic

Method Description

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)

Reference Values

0-19 years: not established

20 years: 150-1,191 mg/24 hours

21 years: 157-1,191 mg/24 hours

22 years: 164-1,191 mg/24 hours

23 years: 171-1,191 mg/24 hours

24 years: 178-1,191 mg/24 hours

25 years: 186-1,191 mg/24 hours

26 years: 193-1,191 mg/24 hours

27 years: 200-1,191 mg/24 hours

28 years: 207-1,191 mg/24 hours

29 years: 214-1,191 mg/24 hours

30 years: 221-1,191 mg/24 hours

31 years: 228-1,191 mg/24 hours

32 years: 235-1,191 mg/24 hours

33 years: 242-1,191 mg/24 hours

34 years: 250-1,191 mg/24 hours

35 years: 257-1,191 mg/24 hours

36 years: 264-1,191 mg/24 hours

37 years: 271-1,191 mg/24 hours

38 years: 278-1,191 mg/24 hours

39 years: 285-1,191 mg/24 hours

40 years: 292-1,191 mg/24 hours

41 years: 299-1,191 mg/24 hours

42 years: 306-1,191 mg/24 hours

43 years: 314-1,191 mg/24 hours

44 years: 321-1,191 mg/24 hours

45 years: 328-1,191 mg/24 hours

46 years: 335-1,191 mg/24 hours

47 years: 342-1,191 mg/24 hours

48 years: 349-1,191 mg/24 hours

49 years: 356-1,191 mg/24 hours

50 years: 363-1,191 mg/24 hours

51 years: 370-1,191 mg/24 hours

52 years: 378-1,191 mg/24 hours

53 years: 385-1,191 mg/24 hours

54 years: 392-1,191 mg/24 hours

55 years: 399-1,191 mg/24 hours

56 years: 406-1,191 mg/24 hours

57 years: 413-1,191 mg/24 hours

58 years: 420-1,191 mg/24 hours

59 years: 427-1,191 mg/24 hours

60 years: 434-1,191 mg/24 hours

>60 years: not established

Test Classification

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

82507

LOINC Code Information

Test ID Test Order Name Order LOINC Value
CITR Citrate Excretion, U In Process

 

Result ID Test Result Name Result LOINC Value
CITRT Citrate Excretion, U 6687-8
TM51 Collection Duration 13362-9
VL49 Urine Volume 3167-4
CITC1 Citrate Concentration 21203-5

Reject Due To

Hemolysis

NA

Lipemia

NA

Icterus

NA

Other

NA

 

Urine Preservative Collection Options

Ambient

No

Refrigerated

Yes

Frozen

Yes

6N HCl

No

50% Acetic Acid

No

Na2CO3

No

Toluene

Preferred

6N HNO3

No

Boric Acid

Yes

Thymol

Yes