Preferred Sample Type
Suitable Specimen Types
- Plain Spot Urine
- 24 Hour Urine (Acid Collection)
Specimen Transport
First Class Post as soon as possible.Sample Processing in Laboratory
Please send to BHH as soon as possible.Sample Preparation
UsualTurnaround Time
5 daysSample Stability
4 ºCUrine 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 fresh random urine or 10 mL aliquot from 24h urine acid collection (collected in to 40ml of 25% conc. HCl). Acidify random urines on receipt.
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 laboratorySpecifications
- EQA Scheme?: Yes
- EQA Status: WEQAS