Citrate is a key intermediate in the tricarboxylic acid cycle. In urine it forms soluble complexes with cations such as Ca++, Mg++ and Fe++, thus inhibiting urinary crystallisation and stone formation. Low levels of urinary citrate excretion (<1.0 mmol/24 h) may be found in patients with distal renal tubular acidosis, malabsorption syndrome and urinary tract infection.
Random urine sample in universal container or 24 hour urine collection (acidified optional)
Random urine: 8 mL
or 24 hour urine collection
Up to 6 weeks
May be done on the same sample as oxalate.
Not currently performed in house; this is a referred test.