Please Note: If extended electrolytes are requested only Na, K and Cl will be registered. If other tests are required please specify.
Sample stability:
-
14 days at 15-25 o C
-
14 days at 2-8 o C
-
Stable at -20 o C
Units: mmo/L
Normal ranges:
|
Neonate: |
134 - 148 |
|
Adult: |
135 - 145 |
Uncertainty of Measurement: 3%
** For Whole Blood Uncertainty of measurement refer to the Blood Gases page
Principle: Ion selective electrode
Reagents: Roche Sodium electrode
Analyser: Cobas Indirect ISE
Increased sodium concentrations may be seen in:
Decreased sodium concentrations may be seen in:
CORRECTED SODIUM
Sodium Correction for Abnormal Protein or Triglyceride
In patients with hyperproteinaemia or hypertriglyceridaemia, the serum sodium measured by laboratory analysers is artefactually decreased due to the "electrolyte exclusion effect". This is known as pseudohyponatremia. Sodium is present only in the water phase of serum; therefore an increased fat or protein phase (lower volume of water phase) means that the sodium concentration measured per litre of serum will be low.
Conversely, in patients with hypoproteinaemia, serum sodium measured using laboratory analysers is falsely increased.
NOTE: This effect does not apply to sodium measured using a blood gas analyser.
Hypertriglyceridaemia (lipemia): The lipoproteins can be removed by high speed centrifugation, and the sodium analysis repeated to obtain a true sodium concentration.
Hyperproteinaemia: The plasma sodium can be corrected using the formula:
Corrected sodium = measured sodium + [ (total protein - 70) / 10]
Hypoproteinaemia: This can be corrected using the formula:
Corrected sodium = measured sodium - [(70 - total protein)/10]
| Total Protein (g/L) | Na (mmol/L) to be added or subtracted |
|---|---|
| 30 | -4 |
| 40 | -3 |
| 50 | -2 |
| 70 | 0 |
| 90 | +2 |
| 110 | +4 |
| 130 | +6 |
References:
1. Tietz. Textbook of Clinical Chemistry 3rd ed (2001), Ch 31.
2. Lang et al., Ann Clin Biochem 39:66-7, 2002.
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