Preferred sample:
Siemens 1.0 mL (vented/self-fill) and non-vented (aspirator) blood gas syringes
The amount of heparin is exactly calibrated to not interfere with analysis of electrolytes, ionised calcium or glucose.
The recommended fill volume is 0.6 mL, but a minimum volume of 0.3 mL of blood can be analysed with no apparent effect on the results.
Put patient label on the barrel of syringe, not the plunger.
Alternatively:
a FULL plain (red-top) tube of blood with minimum air space above is acceptable, if it sent to the laboratory without delay
Send Urgently to Laboratory
External Referrers : Collect in SST tube, which must be at least 80% full, allow to clot for 30 minutes and centrifuge within 1 hour of collection, do not open the tube or aliquot
HEPARIN TUBES ARE NOT SUITABLE
Please do not use the abbreviation ICA when requesting this test - the request may be confused with Islet Cell Antibodies.
TUBES MUST BE AT LEAST 80% FULL
Units: mmol/L
Reference interval:
| Age |
Ionised calcium |
|---|---|
| Day 1 to 1yr |
1.15-1.45 |
| > 1 yr |
1.15 - 1.30 |
Uncertainty of Measurement: 0.05 mmol/L
Conversion factors: mg/100 mL x 0.25 = mmol/L
mmol/L x 4 = mg/100 mL
Principle : Ion-specific calcium electrode
Analyser : Radiometer ABL800 FLEX blood-gas analyser
Ionised calcium is the physiologically active fraction of calcium. It is useful to measure this in patients with abnormal serum proteins (e.g. low albumin, myeloma) where the total calcium measurement may be misleading.
The binding of calcium to protein is pH-dependent; to correct for this effect the ionised calcium result is adjusted to pH 7.4
References :
1. Soldin: Pediatric Reference Ranges. 3rd Ed.
2. Tietz: Clinical Guide to Laboratory Tests. 3rd Ed
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