Sodium (Urine)

Testing Laboratories

Waitematā | Northshore Hospital
Waitematā | Waitakere Hospital

Department

Chemical Pathology

Delphic Registration Code (Alpha Code)

UNA, UR24

Test Code (Numeric Code)

0202

Laboratory Handling

Registration

Code: UR24 when 24 hour urine sample is received

Sample Stability

24 hours

Synonyms

Urinary sodium

Turnaround Time

2 hours

Specimen Type

• 24hr Urine
• Urine

Specimen Requirements

Tube/Container Type:

Preferred

• BD Urine Tube (no additive)

Acceptable

• 24hr Urine Container
• Specimen Container

Minimum Sample Volume (ml)

3

No of Samples Required

1

Paediatric Specimen Requirements

Tube/Container Type:

Preferred

• BD Urine Tube (no additive)

Acceptable

• Specimen Container

Minimum Sample Volume (ml)

1

Test Method

Principle: Ion Selective Electrode
Reagents: Siemens Atellica A-LYTE Integrated Multisensor (IMT NA)
Analyser: Siemens Atellica CH

The normal 24 hour output of sodium in urine varies greatly depending on intake.
Relating the urine output to the serum concentration may help resolve the cause of abnormal serum sodium concentrations. Urinary sodium excretion is not directly related to the body content of sodium but to renal blood flow, and is highly dependent on dietary intake and state of hydration.

There is a large diurnal variation, with sodium excretion during the night being about a fifth of the peak excretion rate during the day.

Sodium output is reduced (usually < 20 mmol/L) in hyponatraemia and hypovolaemic shock, for the first 24-48 hours post-operation, adrenocortical hyperfunction, and conditions causing a reduced glomerular filtration rate (including congestive heart failure causing ineffective circulation). Urine sodium output is increased e.g. with increased intake, adrenal failure (primary or secondary), acute tubular necrosis, salt-losing nephritis, diuretic therapy, alkalosis, hypothyroidism and syndrome of inappropriate ADH (SIADH). Neither of the above lists are complete.

Contact Information