HbA1c is routinely measured for this purpose. The assay is run daily on weekdays and requires an EDTA plasma sample (purple top). Fructosamine can be used as an alternative when HbA1c is not appropriate. Fructosamine reflects blood glucose over two weeks rather than 2 to 3 months as it reflects glycation of albumin rather than haemoglobin. Fructosamine is performed on serum (yellow or red top) and run daily.
Conventionally diabetes mellitus was diagnosed by high fasting or random blood glucose concentrations, or an abnormal oral glucose tolerance test (OGTT) whilst haemoglobin A1c (HbA1c) was used to monitor longer term glycaemic control in patients with known diabetes mellitus.
In 2011, the World Health Organisation (WHO 2011) recommended that HbA1c measurements should also be used to diagnose diabetes in the majority of asymptomatic individuals, and this recommendation has been agreed in the UK (NHS Diabetes 2011).
An HbA1c of 48 mmol/mol or more is consistent with diabetes. If the patient has no symptoms then a second HbA1c result must be obtained within 2 weeks, and if it remains ≥48 mmol/mol diabetes mellitus is confirmed.
HbA1c values of 42 to 47 mmol/mol suggest a high risk of future diabetes. Such individuals should be offered structured lifestyle education and support to delay/prevent development of diabetes, and have an annual HbA1c test.
HbA1c must be measured in an accredited laboratory undertaking recommended quality assurance procedures. Near patient testing is not appropriate when HbA1c is used for the diagnosis of diabetes.
HbA1c is now the preferred method to diagnose diabetes, except in the following situations where this test would be unreliable, and in whom the traditional methods of diagnosis with blood glucose concentrations remain the method of choice:
Increased red cell turnover
Anaemia (haemoglobin < 80 g/L)
?Type 1 diabetes or acute onset of symptoms of diabetes
Children and adolescents
Patients taking steroids and antipsychotic or other medications that cause a rapid rise in blood glucose
Despite this new approach, if an individual has abnormally high random or fasting blood glucose levels or abnormal OGTT, which would be consistent with diabetes on the traditional criteria, then that patient should be considered to have diabetes irrespective of their HbA1c value. Without symptoms of diabetes two abnormal tests of the same type (two high fasting/random blood glucoses or a diabetic OGTT) are required to confirm diabetes mellitus.
Below are some guidelines for fluid analyses which may be of clinical value. Please contact the Duty Biochemist on x16543 if more information is required:
? cirrhotic or malignant
Serum albumin should be simultaneously measured for comparison.
For rare instances pH should be collected anaerobically with heparin and then measured in a blood gas analyser using clot filter.
? pancreatic fistula
Serum amylase should be measured.
Fluoride oxalate (grey top)
Chest Drain Fluid
? bacterial meningitis
Fluoride oxalate (grey top)
? Subarachnoid haemorrhage
Plain universal protected from light
Do not use pod system to send sample to lab.
Serum total protein and bilirubin should be measured simultaneously.
Fluoride oxalate (grey top)
Sent to BCH Biochemistry.
AFP, HCG, placental ALP
Sent to Charing Cross for analysis.
Diagnosis/investigation of inborn errors of neurotransmitter metabolism
Specific collection requirements – contact Duty Biochemist on ext. 16543 well in advance of arranging test.
Sent to Neuroimmunology lab, London.
?narcolepsy with cataplexy
Sent to Immunology, Oxford.
CSF total protein also required for interpretation.
Sent to Neurometabolic unit, London.
Requires discussion with laboratory prior to request (contact Duty Biochemist on ext. 16543)
? contains urine
Comparison of fluid urea and creatinine with serum will identify significant contamination with urine
Occasionally gastric pH may be requested in patients suspected of intestinal reflux or achlorhydria. Normally the fasting gastric pH is about 1-2.
Pancreatic Cyst Fluid
? Ca pancreas
Fluoride oxalate (Grey top) required
Four types of fluids can accumulate in the pleural space:
Serous fluid (hydrothorax)
Pus (pyothorax or empyema)
? transudate or exudates
A transudate fluid is produced through pressure filtration without capillary injury while exudate is "inflammatory fluid" leaking between cells.
Most common causes of pleural exudates are bacterial pneumonia and malignancy.
Most common causes of pleural transudates are left ventricular failure and cirrhosis.
TP <25g/L indicates transudate.
TP >35g/L indicates exudate.
Light’s criteria applies to pleural fluid TP between 25 and 35g/L.
A fluid is an exudate if any of the following apply:
Ratio of fluid protein to serum protein is >0.5
Ratio of fluid LDH to serum LDH is >0.6
Pleural fluid LDH is > 2/3rds the upper reference limit for plasma LDH.
Measure serum protein and LDH simultaneously
This is part of British Thoracic Society’s guidelines for differentiating infective from non-infective pleural effusions, can only be measured on fresh specimen collected anaerobically using a dedicated blood gas analyzer. This analyser can be found on W513 (respiratory).
Patient's serum amylase should be measured for comparison.
? rheumatic cause
Fluoride oxalate (grey top) tube required.
Sent to Immunology, Sheffield.
Salivette or Plain universal
Saliva specimens should be collected using a Sarstedt cortisol salivette (these can be requested from Chromatography). Saliva collected into a plain container by passive drool is also acceptable.
Refer to Microbiology
?cause of metabolic acidosis
In patients with a metabolic acidosis and suspected renal tubular acidosis, urine pH measurement is indicated.
Protection of Personal Information – Clinical Laboratory Services comply with the Trust Data Protection Policy and have procedures in place to allow the Directorate and it’s employees to comply with the Data Protection Act 1998 and associated best practice and guidance.
University Hospitals Birmingham medical laboratories at Queen Elizabeth Hospital, Heartlands Hospital, Good Hope Hospital and Solihull Hospital are UKAS (United Kingdom Accreditation Service) accredited to the ISO 15189:2012 standard. For a list of accredited tests and other information please visit the UKAS website using the following link: https://www.ukas.com/find-an-organisation/
Molecular Pathology is a UKAS accredited medical laboratory No. 8759
Biochemistry is a UKAS accredited medical laboratory No. 8910
Haematology and Transfusion is a UKAS accredited medical laboratory No. 8784
Clinical Microbiology is a UKAS accredited medical laboratory No. 8760
Cellular Pathology is a UKAS accredited medical laboratory No. 10141
Musculoskeletal laboratory is a UKAS accredited medical laboratory No. 9897
Heartlands, Good Hope and Solihull Hospital pathology laboratories are a UKAS accredited medical laboratory No.8217.
Tests not appearing on the UKAS Schedule of Accreditation currently remain outside of our scope of accreditation. However, these tests have been validated to the same high standard as accredited tests and are performed by the same trained and competent staff.