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Test Code RAT10 Citrate/Creatinine Ratio, Urine


Specimen Required


Only orderable as part of a profile. For more information see CITRA / Citrate Excretion, Random, Urine.


Secondary ID

606642

Useful For

Calculating the citrate concentration per creatinine

 

Diagnosing risk factors for patients with calcium kidney stones

 

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

Method Name

Only orderable as part of a profile. For more information see CITRA / Citrate Excretion, Random, Urine.

 

Calculation

Reporting Name

Citrate/Creatinine Ratio

Specimen Type

Urine

Specimen Minimum Volume

1 mL

Specimen Stability Information

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

Reject Due To

All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.

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 is subject to therapy by correcting acidosis, hypokalemia, or hypomagnesemia by altering diet or using drugs such as citrate and potassium.

Reference Values

Only orderable as part of a profile. For more information see CITRA / Citrate Excretion, Random, Urine.

 

No established reference values

Interpretation

A low citrate value 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.

 

Very low citrate levels suggest investigation for the possible diagnosis of metabolic acidosis (eg, renal tubular acidosis).

 

For children ages 5 to 18, a ratio of less than 0.176 mg citrate/ mg creatinine is below the 5% reference range and considered low.(1)

Cautions

Drugs that lower systemic pH, potassium, and/or magnesium also lower urine citrate and are to be avoided in patients with tendency to form calcium stones. Conversely, drugs that raise systemic pH, potassium, and/or magnesium may raise urine citrate and should be considered when treating patients or interpreting results.

Clinical Reference

1. Srivastava T, Winston MJ, Auron A et al: Urine calcium/citrate ratio in children with hypercalciuric stones. Pediatr Res. 2009;66:85-90

2. 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

3. Lieske JC, Wang X: Heritable traits that contribute to nephrolithiasis. Urolithiasis. 2019 Feb;47(1):5-10

4. 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. doi: 10.2215/CJN.08210813

Method Description

This test calculates the citrate concentration per creatinine. This calculation is performed in the Laboratory Information system, SCC Soft.

Day(s) Performed

Monday through Saturday

Report Available

Same day/1 day

Specimen Retention Time

7 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

Not Applicable

CPT Code Information

82507

LOINC Code Information

Test ID Test Order Name Order LOINC Value
RAT10 Citrate/Creatinine Ratio 13722-4

 

Result ID Test Result Name Result LOINC Value
RAT10 Citrate/Creatinine Ratio 13722-4