Preanalytical-Chemical Pathology

Preanalytical consideration:

1. Request form

• All specimens must be accompanied by the PER-PAT-301 form with a complete and relevant clinical information.

• The sample containers and request form must be labelled with a least two identifiers (i.e. name of patient and patient's IC number) and the name of test requested.

• All special chemistry requests must have adequate relevant clinical information and diagnosis. Failure to do so may lead to rejection.

• Empty form and photostated form with prefilled information & signature is strictly prohibited for any request.

• All form must be signed and stamped by medical doctor. Certain special tests and referral tests might need additional counter-signed by specialist.

• For facility that do NOT have a resident specialist (e.g. district hospital or small-scale health clinic), please write the consulted specialist information (full name with MMC full registration number and contact number) in the requesting lab form for documentation purposes. Failure to do so may result in rejection of the request. This is to prevent unnecessary request.

• Urgent Chemical Pathology Test Request

  1. The word URGENT must be stamped or written (in red ink) on the upper right - hand corner of the request form.

  2. Urgent requests must be separated from non-urgent requests.

  3. For urgent request, do not send sample via pneumatic tube.

  4. Urgent non-routine Chemical Pathology test:

     • Only offered for Thyroid Function Test, beta-hCG, Procalcitonin and Ferritin.

     • Call Medical Officer/Pathologist to place request.

     • Once request is placed, send sample with form (include name of consulted MO/Pathologist) to Makmal Integrasi dan Patologi Kimia.

  5. For referring lab (from outstation), all URGENT REQUEST, AMMONIA, CSF BIOCHEMISTRY and HS TROPONIN I SAMPLES must be sent directly to kaunter Makmal Integrasi dan Patologi Kimia, Aras 2, Menara Berkembar HQE.

2. Specimen

• See Order of Draw.

• Always label sample tubes and container with patient’s full name, identification number/MRN, date and time of collection.

• Test sent to referral laboratories SHOULD NOT SHARE same sample tube with tests done in-house.

• For chemical pathology tests, the minimum sample volume is 4 mL.

• For sample from OUTSTATION LABORATORIES,

  • Please take note on type of sample needed for analysis (Refer test list - sample type in bracket)

  • Fresh sample must be collected via CORRECT type of blood collection tube. 

  • Sample MUST be spun at 3500RPM for 10 minutes.

  • Separated serum/plasma MUST be sent in a secondary tube and to be kept in a frozen state (for storage) before being send to Integrated Laboratory and Chemical Pathology Unit, QEH in a cool box packed with ice.

  • For urine sample request, please send in a secondary tube with a minimum volume of 5 mL. For 24-hour urine test, please write the volume of the urine on the request form. Kindly refer surat edaran HQE.700-4/1/23 Jld.2 (13) dated 12th November 2024 for further information.

• Follow Best Practices in Phlebotomy (Procedure for drawing blood):

3. Factors affecting test results

• Hemolysis

  • ALP, AST, Direct Bilirubin, GGT, IgM, LDH, Phosphate, Potassium, Total Protein, UIBC, Vitamin B12 and Folate are markedly affected by hemolysis.

  • Following are steps that can be taken to reduce sample hemolysis:

    • Choose the right needle gauge (21 - 23G). Using a narrower needle increases physical cell damage during collection.

    • Allow alcohol cleansed puncture site to fully dry ~ 30 seconds.

    • Limit tourniquet time to 1 minute or less before accessing the vein.

    • Discontinue sluggish draws that can be cause by collapsed veins and improper needle placement.

    • Avoid "milking" the puncture site.

    • Apply gentle, steady pressure when pulling the plunger back. Avoid pulling the plunger back too forcibly.

    • Never squirt the sample into the tube through the needle or at high velocity.

    • Gently invert tubes with additives as recommended by the manufacturer of the tube. Avoid vigorously mixing.

    • Fill tubes to the correct volume. Underfilling the tube can promote hemolysis.

    • Avoid prolonged storage of the sample. Deliver specimens promptly to the laboratory.

• Contamination

  • Contamination of a blood samples may lead to an incorrect result.

  • Avoid sampling from IV infusion sites as it can cause dilution effect or falsely increased analytes such as Glucose or Electrolytes.

  • Avoid decanting blood from one sample tube to another. Follow 'Order of Draw' to avoid cross contamination. For example, EDTA contamination can cause falsely increase Potassium and falsely low Calcium.

4. Miscellaneous

• Lab Turn-Around Time (LTAT):

1. Urgent 24-hour tests : 60 to 90 minutes

2. Routine 24-hour tests: 3 hours

3. Therapeutic Drug Monitoring (TDM): 3 hours

4. Special Chemistry test: 3 to 5 working days

5. Protein Electrophoresis: 15 working days

6. Referred test: depending on the LTAT of the referral center + 7 working days

• Retesting Interval:

  1. All test requested within retesting interval MUST BE consulted with Medical Officer or Chemical Pathologist Integrated Laboratory HQE. Failure to do so may lead to rejection. Please check and trace previous lab results from iLab prior to sending new test request. 

1. Creatinine: Once daily

2. Osmolality: Once daily

3. Liver Function Test: Once every three (3) days

   • Exception (Please CLEARLY STATE the indication to repeat in the request form):

     • Acute Poisoning (e.g. Acetaminophen poisoning).

     • Acute Liver Injury/Acute Hepatitis due to any cause.

     • Pre- and Post-Hepatobiliary Procedure/Operation.

     • Intensive Care Unit (ICU) patients.

     • Patient on Total Parenteral Nutrition (TPN).

4. Specific Protein (Ig G/A/M, C3, C4): Once every five (5) days.

5. Tumour Markers (except Total BhCG): Once a month.

6. Thyroid Function Test: Once a month. Exception for:

   • Paediatric patient. Kindly write patient’s age/day of life.

   • Maternal/Antenatal/Postnatal.

   • Cases under Endocrine clinic follow-up.

   • All cases that require retesting prior to allowable retesting interval must be discussed with Chemical Pathologist HQE.

7. Lipid Profile: Once every three (3) months.

8. HbA1c: Once every six (6) months.

   • Patient with transfusion-dependent hematological disorders (e.g. Thalassemia Major) will be rejected due to non-suitability of sample for analysis.

9. Iron Studies: Once every three (3) months.

   • Exception (Please CLEARLY STATE the indication to repeat in the request form):

     • Ferritin for Covid 19

     • Ferritin for Hemophagocytic lymphohistiocytosis (HLH)

10. Protein Electrophoresis: Once every three (3) months.

11. Rheumatoid Factors (RF): Once every six (6) months.

12. Vitamin B12 and Folate: Once every three (3) months.

• Add-on Test (Request for additional tests on a previously analysed specimens applicable to in-house HQE patient)

  1. Request can be placed ONCE per specimen by clinician.

  2. For routine biochemistry tests, place request via phone call to the laboratory at ext. 8241.

  3. For non-routine biochemistry tests such as hormones, tumor markers, iron studies, complements and immunoglobulins, request shall be placed directly to Chemical Pathologist within 24 hours of sampling date.

  4. Information required is as follows:

     • Patient Name and ID

     • Specimen Lab ID

     • Tests to be added

     • Any additional relevant clinical details

     • Name of requesting clinician

  5. Once request is placed, requesting clinician shall fill in a new laboratory form with information as below:

     • Patient's name and ID

     • Location of ward/clinic

     • The comment 'Add-on Request' is added to the form

     • Test/tests requested for add-on

     • Specimen Lab ID

     • Name, sign and stamp of requesting clinician

  6. Send the new laboratory form immediately to the lab

  7. Lab will accommodate add-on test request based on the nature of specimen (i.e. specimen type, volume, presence of hemolysis, specimen received time)

  8. Acceptance criteria for add-on test is as follows:

     • Specimen is NOT hemolysed

     • Sufficient specimen volume

     • Specimen received in lab within 3 hours of duration for routine biochemistry tests:

       • ALT, Albumin, ALP, Amylase, Total Bilirubin, Calcium, Chloride, Total Cholesterol, Creatine Kinase, Creatinine, C-Reactive Protein, GGT, HDL, Magnesium, Sodium, Triglyceride, hs-Troponin I, Urea, Uric Acid.

       • Acetaminophen and Salicylate.

     • Tests that CANNOT be added:

       • Routine chemistry: Ammonia, AST, Direct Bilirubin, Glucose, Lactate, LDH, Phosphate, Potassium, Total Protein.

       • Therapeutic Drug Monitoring (TDM).

       • Non-routine biochemistry: Vitamin B12, Folate, iPTH, tPSA, Procalcitonin.

  9. If request is not suitable for add-on test: comment will be added in patient report.

  10. Add-on request for panel testing is discouraged and tests that cannot be add-on will not be included in the panel test request.

  11. In the event of Total Lab Automation (TLA) breakdown, add-on test will not be offered for all tests.