Specimen Collection
2 mL Urine (Random)
24hr Urine
Reference Intervals
Reference interval:
The output of sodium in the urine depends on the sodium intake, if the patient is in a steady state.
Less than 100 mmol/d : low sodium intake
100 - 200 mmol/d: average sodium intake
>200 mmol/d : high sodium intake
There is a large diurnal variation in sodium excretion, being much lower at night.
Uncertainty of Measurement: 5%
Turnaround Time: Within 3 hours
Assay Method
Principle
: Ion selective electrode
Reagents:
Roche Sodium electrode
Analyser:
Cobas Indirect ISE
Diagnostic Use and Interpretation
The urinary sodium concentration may be helpful in determining the cause of hyponatraemia or oliguria.
In a hyponatraemic patient, a low urine sodium (< 20 mmol/L) indicates a strong aldosterone drive, suggesting that hypovolaemia or sodium depletion is present.
In an oliguric patient, a low urine sodium (< 20 mmol/L) indicates prerenal uraemia, rather than intrinsic acute renal failure.
In a hyponatremic patient, urine sodium concentrations > 40 mmol/L are typically seen in SIADH, Addison's disease, renal tubular damage or diuretic-induced hyponatraemias. However low urinary sodium does not exclude these conditions if sodium depletion is present.
Contact Information
Emails to
chemicalpathologist@adhb.govt.nz
will receive priority attention from the on-call chemical pathologist.
If the query concerns a specific patient please include the NHI number in your email.
If email is not a suitable option, please contact the on-call chemical pathologist via
Lablink (Auckland City Hospital ext. 22000 or 09-3078995).
Individual chemical pathologists may be contacted but will not be available at all times.
After-hours
: contact
Lablink (Auckland City Hospital ext. 22000 or 09-3078995) or hospital operator for on duty staff after hours.
Dr Samarina Musaad
(Clinical Lead)
:
SamarinaM@adhb.govt.nz
ext. 22402
Dr Cam Kyle:
CampbellK@adhb.govt.nz
ext 22052
Dr Weldon Chiu:
WeldonC@adhb.govt.nz
ext. 23427
Dr Campbell Heron:
CHeron@adhb.govt.nz
ext. 23427
Dr Sakunthala Jayasinghe:
Sakunthala@adhb.govt.nz
ext. 23427