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HelpTest ID: CITR Citrate Excretion, 24 Hour, Urine
Reporting Name
Citrate Excretion, 24 Hr, UUseful For
Diagnosing risk factors for patients with calcium kidney stones
Monitoring results of therapy in patients with calcium stones or renal tubular acidosis
Clinical Information
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 that 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.
Interpretation
Any value less than the mean for 24 hours represents a potential risk for kidney stone formation and 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 is needed for the possible diagnosis of metabolic acidosis (eg, renal tubular acidosis).
Special Instructions
Analytic Time
Same day/1 dayDay(s) and Time(s) Performed
Monday through Saturday; 8 a.m.-4 p.m.
Clinical Reference
1. Hosking DH, Wilson JW, Liedtke RR, Smith LH, Wilson DM: The urinary excretion of citrate in normal persons and patients with idiopathic calcium urolithiasis. Lab Clin Med. 1985 Dec;106(6):682-689.
2. Lieske JC, Wang X: Heritable traits that contribute to nephrolithiasis. Urolithiasis. 2019 February; 47(1): 5-10
3. Lieske JC, Turner ST, Edeh SN, Smith JA, Kardia SLR: Heritability of urinary traits that contribute to nephrolithiasis. Clin J Am Soc Nephrol. 2014 May;9(5):943-950
Method Name
Enzymatic
Specimen Type
UrineNecessary Information
Patient's age and 24-hour volume are required.
Specimen Required
Patient Preparation: Any drug that causes alkalemia or acidemia may be expected to alter citrate excretion and should be avoided, if possible. The patient must avoid laxative use for 24 hour collection period.
Supplies:
-Diazolidinyl Urea (Germall) 5.0 mL (T822)
-Aliquot Tube, 5 mL (T465)
Container/Tube: Plastic tube
Specimen Volume: 4 mL
Collection Instructions:
1. Add 5 mL of diazolidinyl urea (Germall) as preservative at start of collection or refrigerate specimen during and after collection.
2. Collect urine for 24 hours.
3. Mix well before taking 4-mL aliquot.
Additional Information: See Urine Preservatives-Collection and Transportation for 24-Hour Urine Specimens in Special Instructions for multiple collections.
Specimen Minimum Volume
1 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Urine | Refrigerated (preferred) | 14 days | |
| Frozen | 14 days |
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, 24 Hr, U | 6687-8 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| CITRT | Citrate Excretion, 24 Hr, U | 6687-8 |
| TM51 | Collection Duration | 13362-9 |
| VL49 | Urine Volume | 3167-4 |
Forms
If not ordering electronically, complete, print, and send a Renal Diagnostics Test Request (T830) with the specimen.
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