Test Catalog

Test ID: CITR2    
Citrate Concentration, Random, Urine

Useful For Suggests clinical disorders or settings where the test may be helpful

Diagnosing risk factors for patients with calcium kidney stones


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

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 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 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.

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


No established reference values

Interpretation Provides information to assist in interpretation of the test results

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 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 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 Recommendations for in-depth reading of a clinical nature

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