Interpretive Handbook

Test 9329 :
Citrate Excretion, 24 Hour, Urine

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 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.

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

Interpretation Provides information to assist in interpretation of the test results

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 for the possible diagnosis of metabolic acidosis (eg, renal tubular acidosis).

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, lower urine citrate and are to be avoided in patients with a tendency to calcium stones.


Conversely, drugs that raise systemic pH, potassium, and/or magnesium, may raise urine citrate and should be considered in treating patients or interpreting results.

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.

0-19 years: not established

20 years: 150-1,191 mg/specimen

21 years: 157-1,191 mg/specimen

22 years: 164-1,191 mg/specimen

23 years: 171-1,191 mg/specimen

24 years: 178-1,191 mg/specimen

25 years: 186-1,191 mg/specimen

26 years: 193-1,191 mg/specimen

27 years: 200-1,191 mg/specimen

28 years: 207-1,191 mg/specimen

29 years: 214-1,191 mg/specimen

30 years: 221-1,191 mg/specimen

31 years: 228-1,191 mg/specimen

32 years: 235-1,191 mg/specimen

33 years: 242-1,191 mg/specimen

34 years: 250-1,191 mg/specimen

35 years: 257-1,191 mg/specimen

36 years: 264-1,191 mg/specimen

37 years: 271-1,191 mg/specimen

38 years: 278-1,191 mg/specimen

39 years: 285-1,191 mg/specimen

40 years: 292-1,191 mg/specimen

41 years: 299-1,191 mg/specimen

42 years: 306-1,191 mg/specimen

43 years: 314-1,191 mg/specimen

44 years: 321-1,191 mg/specimen

45 years: 328-1,191 mg/specimen

46 years: 335-1,191 mg/specimen

47 years: 342-1,191 mg/specimen

48 years: 349-1,191 mg/specimen

49 years: 356-1,191 mg/specimen

50 years: 363-1,191 mg/specimen

51 years: 370-1,191 mg/specimen

52 years: 378-1,191 mg/specimen

53 years: 385-1,191 mg/specimen

54 years: 392-1,191 mg/specimen

55 years: 399-1,191 mg/specimen

56 years: 406-1,191 mg/specimen

57 years: 413-1,191 mg/specimen

58 years: 420-1,191 mg/specimen

59 years: 427-1,191 mg/specimen

60 years: 434-1,191 mg/specimen

>60 years: not established

Clinical References Provides recommendations for further in-depth reading of a clinical nature

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