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Preferred Sample Type

Urine Citrate

Suitable Specimen Types

  • 24 Hour Urine (Acid Collection)
10 mL Urine

Specimen Transport

First Class Post as soon as possible.

Sample Processing in Laboratory

Please send to BHH as soon as possible.

Sample Preparation

Usual

Turnaround Time

5 days

Sample Stability

4 ºC

Urine Citrate

General Information

Hypocitraturia is recognized as an important cause of nephrolithiasis, particularly calcium stones. Urinary citrate combines free calcium ion, thereby forming soluble calcium citrate and resulting in reduction of urinary supersaturation of calcium oxalate and phosphate. Once calcium oxalate and phosphate crystals are formed in the urine, citrate inhibits both crystal growth and aggregation that are presumed to be a prerequisite for stone formation. Moreover, monosodium urate crystallization known as another risk for formation of calcium oxalate stones by heterogeneous nucleation, is also inhibited by urinary citrate. All these properties of citrate are considered to help prevent urinary stone formation.

Urinary Citrate measurement may therefore be of use in the investigation of renal stone formers.

Patient Preparation

None

Notes

May be done on same sample as oxalate.

10 mL aliquot from 24h urine acid collection (collected in to 40ml of 25% conc. HCl). 

Reference Range

Provided by Reference Laboratory:

24 hour excretion:

Males : 0.6 ‑ 4.8 mmol/24 h

Females : 1.3 ‑ 6.0 mmol/24 h.

Random excretion (Citrate/creatinine ratio):

Males : 0.04 ‑ 0.33 mmol/mmol creatinine

Females :0.11 ‑ 0.55 mmol/mmol creatinine

Source of Reference Range

Referral laboratory

Specifications

  • EQA Scheme?: Yes
  • EQA Status: WEQAS