Clinical Biochemistry

Biochemistry (last updated 19 Aug 2015)

Tests and Turnaround times Protocols
Specimen requirements Patient Preparation

Urgent Requests

On Call Service and Repertoire

Reference ranges

Recommended testing frequencies for biochemical analyses

Clinical Advice Referral hospital details

Results & Reports

Safe Sample Collection

Specimen transportation

Ordering supplies

Contact Pathology

Where to find us

Opening Hours

If you have any questions or queries about new services please contact the laboratory

Useful Links

Labtestsonline - a public site that explains Pathology tests for patients

NHS Direct - a public site that provides information and advice about health, illness and health services.

Sample Processing and Analysis

All samples are processed as soon as possible upon arrival in the laboratory. They are analysed thereafter as routine or emergency, depending on the urgency of the request.  More than 90% of routine samples are analysed on the day of arrival and most of the remainder within one to three days of receipt.  There will inevitably be a longer delay for specialised testing and tests referred to other laboratories.

Urgent Requests

Urgent Requests Urgent requests are defined as those essential for the immediate management of the patient.  Any other request must be discussed with the Duty Biomedical Scientist (BMS) in the first instance who may refer to a Biochemist or the Consultant Chemical Pathologist.

During normal working hours the requester must telephone the laboratory. Those tests requiring urgent analysis will be agreed.  Results for all  wards will be released onto the computer system.  The requester will be advised of any grossly abnormal or unexpected results. Results to all other sources will be telephoned.  The request form should also be marked URGENT and the specimen taken immediately to the local Pathology Laboratory.  General Practitioners asking for Urgent analyses will be responsible for getting the sample(s) to the Department of Clinical Biochemistry

NB.  Samples marked 'Urgent' or 'Please Phone' but not preceded by a telephone call may not be analysed as a priority sample. Prior notification is essential (a) to distinguish urgent samples from the numerous routine samples, and (b) to ensure the Laboratory can take action if an expected urgent sample fails to arrive.

Non urgent requests or requests not available urgently without prior consultation Non urgent requests ticked on request forms together with urgent requests will be  analysed routinely and the results will be available the same or the next working day (depending if the request was made during the week-day or week-end), the aim being to have them available for the next morning ward round.  Urgent written requests for tests that are not usually available and have not been discussed with the biochemist or consultant on call will not be processed until after consultation.


Outside routine working hours, the On-Call Clinical Biochemistry BMS should be contacted .  The requesting doctor is responsible for ensuring that the specimen reaches the laboratory.

The laboratory makes allowances for pre operative assessment of patients due for surgery after the weekend but admitted over the weekend and will make the non-urgent results available on the day of admission provided it has been forewarned.

All common out-of-hours tests will be run as soon as possible and you should not normally have to inform them that they are being sent. Our target turnaround time from receipt in the biochemistry lab to reporting of results is 90 % within 1 hour for the On Call Repertoire. You will need to contact the on-call BMS for the following:

  • A sample that you need extremely urgently
  • The patient is close to breaching the A&E turnaround time
  • A test that is not part of the usual repertoire of emergency tests
  • A test that is unstable
  • The sample does not seem to have been received by the laboratory (is not on the Pathology Results viewer) and was sent a long time previously.

Click here for full list of tests available out of hours.

Clinical Biochemistry clinical advice (updated 29 Jul 2015)

A team consisting of a Chemical Pathologist and Clinical Scientists offer clinical advice and interpretative service during the normal routine service. See Biochemistry Contacts.  Consultant cover is available at all times. For clinical advice out of hours please contact MTW switchboard to speak to a consultant.

Clinical Biochemistry turnaround times

  • A+E and urgent samples analysis of emergency/out of hour repertoire 90 % within 1 hour of receipt in laboratory

Ward patient routine biochemistry 90 % within 4 hours of receipt in laboratory

General Practice and out-patients 90 % within 24 hours of receipt in laboratory

See Master Repertoire A-Z for specific Turnaround times

Please note days are quoted are normal working days, Monday to Friday 9.00 -17.30 excluding Bank Holidays

Reference ranges

Biochemistry reference ranges are not published. They change with new instrumentation and methodology and they are age and gender specific. Relevant reference limits, or target values, are therefore reported with the result. If clinical advice or specific information is required, click here for contact details.

Patient Preparation

If tests requested require the patient to be fasting. patients must not eat or drink anything (except water) for minimum of 12 hours before having their blood taken. During this time patient should refrain from smoking, chewing gum or exercise. After the specimen is collected they may resume normal diet. Patients should continue to take their medication unless instructed by their Doctor not to. However, each Diabetes Mellitus patient should be instructed individually according to their diabetic state, medication etc.

For any other specific patient preparation see specimen requirement table.

Specimen Requirements

  • Detailed sample collection instructions are available with certain specimen type
  • Unless specific transportation procedures are stated, samples should be kept at room temperature (15oC - 25oC) out of direct sunlight until transportation which should be within 4 hours post collection. Contact laboratory for further information if required
  • Additional tests on samples already in the laboratory may be requested up to 72 hours after sample collection in most cases. Contact laboratory.

The following describes the specimen containers required for various Clinical Biochemistry investigations. See individual tests for any specific instructions regarding that investigation.

Volume required

A full 4 ml gel tube is sufficient for most routine tests but, if large numbers of tests are required, a second bottle may be needed. The specific sample requirements of certain tests must also be borne in mind. If only a small sample is taken, the laboratory will strive to produce results on as many tests as possible, but, in such circumstances, it is prudent to prioritise the tests requested. This is particularly relevant to paediatric requesting. If unsure of the volume necessary for specific tests, please contact the laboratory for advice prior to venepunture.


Gold top vacuette tubes (Greiner bio-one) with gel are suitable for most routine blood tests unless indicated. One 4 mL tube is sufficient for all routine profiles. An additional red top vacuette tube without gel is required for drugs, hormones and other non-routine tests. A single Gold top sufficient for routine biochemistry and immunology at Maidstone. An additional gold top is required for Immunology if sample to be received at Pembury. Please do not use 9 mL tubes for Biochemistry

Important: please see blood sample collection instructions


24 hour urine collection containers (plain or with acid preservative) are available from Clinical Biochemistry. For collection instructions click here.

Random samples in plain 30 mL (white top) containers can be used for many Biochemistry tests. See specimen requirement table

Urine Containers containing boric acid (red top) are Never Acceptable. Also please note sputum pots
should not be used for urine samples.

Cerebrospinal Fluid(CSF)

 Volume requirement for CSFs. Please note 1 mL is approximately 20 drops from the Luer connector on a needle.

  • At least 0.5 mL (10 drops) CSF into grey top fluoride-oxalate tube (minimum volume 0.2 mL (4 drops)
  • At least 1 mL (20 drops)in Universal container. Please label universal with draw number. Generally Bottle Two for Protein and Last draw for Xanthochromia

Please note sputum pots should not be used for CSF samples and ensure that Biochemistry sample are sent directly to Biochemistry laboratory (NOT via Vacuum tube or Microbiology)

Specimen Container Code Description
UNI (white) Plain 20mL universal container (no additive, White Top) UNI(white)
PLAIN 24 24 hr urine container (no additive)

Click here for patient leaflet>
plain 24 urine
ACID 24 24 hr urine container (with hydrochloric acid added)

Click here for patient leaflet>

Faeces Specimens

Specimen Container Code Specimen Collection Description
FAEC (Blue) Either ask the patient to defaecate into a clinically clean bedpan or ask the patient to defaecate onto 'clingfilm' across the toilet pan or to defaecate onto newspaper.  Scoop enough material to fill a third of the specimen container with the spoon incorporated in the specimen container lid.  If the faeces is liquid it may be easier to either use a sterile syringe to withdraw the specimen from the bedpan or use the specimen container directly on the anus. Faeces container (30 mL plastic container with blue top) faeces


Please state origin of fluid on the request form. Please note sputum pots should be avoided for fluid samples.

Specimen Container Code Description
FLU OXA (Grey) 4 mL Fluoride Oxalate (Grey Top) grey top
UNI (white) Plain 20 mL universal container (no additive, white Top) UNI(white)


Specimen Container Code Description
FLU OXA (Grey) 4 mL Fluoride Oxalate (Grey Top) Grey top
UNI (white) Plain 20 mL universal container (no additive, white Top) UNI(white)

Stone (Calculus) Samples

Specimen Container Code Description
UNI (white) Plain 20 mL universal container (no additive, white Top) UNI(white)

Please note that for some specialised tests different containers and/or additives are required. Please consult the specimen requirement table or contact Clinical Biochemistry if in doubt.




Biochemistry On Call repertoire