Routine Requests

Samples for analysis should arrive in the laboratory as early as possible each morning.  The laboratory will endeavour to provide results the same day on all specimens received before 8.00 pm which are performed ‘in house’ see test repertoire.

 

 Out-of-Hours Requests

The following investigations are available out-of-hours:

Serum

      • Alcohol*
      • Amylase
      • b-HCG
      • Bilirubin
      • Calcium Profile
      • CRP (C-Reactive Protein)
      • Creatine kinase
      • Digoxin
      • Glucose
      • Gentamicin
      • Iron
      • Lipid Profile
      • Lithium
      • Liver Profile
      • Magnesium
      • Osmolality
      • Paracetamol (Take sample at least 4 hours post-ingestion)
      • Phenytoin
      • Random Cholesterol
      • Salicylate (Only if clinically indicated, not as routine OD screen)
      • Theophylline
      • Troponin I
      • Urea and Electrolytes
      • Uric acid
      • TSH**
      • FT4**
      • FT3**
      • Folate**
      • Ferritin**
      • B12**
      • Cortisol**
      • Vitamin D**

*Alcohol is not to be requested routinely on A&E patients smelling of alcohol

** Available 09:00 – 20:00 weekends and Bank Holidays.

 Whole Blood

      • Blood gases
      • Carboxyhaemoglobin

Urine

      • Electrolytes
      • Osmolality
      • Protein

Cerebrospinal Fluid

      • Glucose (should be accompanied by a serum glucose)
      • Protein

 

 Guidance for Out-of-Hours Requesting

The following table provides guidance in the use of the available out-of-hours investigations by detailing clinical conditions in which they may be of value.  Inclusion of a clinical condition or situation in this list does not imply that the investigation must always be done.  The requesting clinician must exercise his/her clinical judgement and only request those tests that will influence the immediate management of the patient.

Indiscriminate use of the emergency service will be investigated by the Chemical Pathologist.

Biochemical Investigation Clinical Condition / Situation

Amylase

 Abdominal pain with a high index of suspicion of pancreatitis

β-HCG

 ? Ectopic pregnancy – only if the result will influence the immediate management of the patient, otherwise take the sample and send to the laboratory for later analysis

Calcium

 Acute pancreatitis
Clinical signs or symptoms suggestive of hypo/hypercalcaemia
Massive transfusion
Post-thyroidectomy or parathyroidectomy

Digoxin

 ? Compliance / ? Toxicity
Prior to further therapy if already on treatment

Glucose

 Confusion, stupor or coma
Diabetes
Poisonings – especially paracetamol and salicylate

Iron

 Definite or suspected overdose

Lithium

 ? Toxicity
Definite or suspected overdose

Magnesium

 Resistant hypocalcaemia
Unexplained fits (Serum calcium = first line)

Osmolality

 Hyponatraemia
Poisonings

Paracetamol

 Definite or suspected overdose
NB. Take sample at least 4 hours post ingestion

Phenytoin

 ? Compliance / ? Toxicity
Prior to further therapy if already on treatment

Salicylate

 Definite or suspected overdose – but only if suspected clinically(not as a routine screening test)

Theophylline

 ? Compliance / ? Toxicity
Prior to further therapy if already on treatment

Urea & Electrolytes

Cardiac arrhythmias
Dehydration
Diabetes mellitus
Intensive IV therapy
Metabolic confusion, stupor or coma
Myocardial infarction
Patients on drugs which affect electrolyte balance or are affected by electrolyte imbalance.
Renal impairment
Shock

Blood Gases

 Cardiac/respiratory arrest
Diabetes mellitus
Metabolic confusion, stupor or coma
Poisonings
Respiratory problems
Shock

Carboxyhaemoglobin

 Definite or suspected exposure to carbon monoxide

Urine Osmolality and/or Electrolytes

 Hyponatraemia
Renal failure

 

Cerebrospinal fluid (CSF)

Bacteriological investigation is of prime importance and preferred to Biochemistry but protein and glucose may be of assistance if the Bacteriology is equivocal or there has been partial antibiotic treatment.

Requests for ‘xanthochromia screening’ should be limited to those cases in which there is genuine clinical suspicion of subarachnoid haemorrhage, the presenting headache was at least 12 hours ago and the scan is negative.  The sample should be the last CSF sample obtained, collected into a plain tube, at least 0.5 mL volume and protected from light ie. sent to the laboratory in a brown paper envelope along with a completed request form. Xanthochromia requests are analysed at Rotherham not on site.

Requests for CSF oligoclonal bands must be accompanied by a serum sample.

NB. Do not use the vacuum delivery system for the transport of CSF samples (or any other ‘precious’ specimens).

Please note:

It may be possible to provide analyses not listed above out-of-hours if they are essential for immediate patient management but all such requests must be discussed with the Duty Biochemist.

A medically qualified Consultant Biochemist/Chemical Pathologist is always available to discuss individual cases.  The laboratory will advise how to contact the duty clinician.