Table Of ContentA GUIDE TO LABORATORY
INVESTIGATIONS
A GUIDE TO LABORATORY
INVESTIGATIONS
7th edition
Michael F. McGhee, Caroline A. Saxelby, and Niall McKay
Seventh edition published 2022
by CRC Press
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ISBN: 978-0-367-50371-0 (hbk)
ISBN: 978-0-367-50077-1 (pbk)
ISBN: 978-1-003-04968-5 (ebk)
DOI: 10.1201/9781003049685
Typeset in Bembo
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CONTENTS
Preface vi
Author Biographies viii
Glossary ix
Introduction xiv
1 Haematology 1
2 Microbiology 33
3 Fertility and women’s health 51
4 Rheumatology and immunology 59
5 Biochemistry 68
6 Miscellaneous 106
7 Quick reference guide for clinical scenarios 116
8 Actions following ECG automatic read-outs 127
Index 134
PREFACE TO THE SEVENTH EDITION
When I entered NHS General Practice in 1981, I soon realised the benefit of a
handbook to aid interpretation of the huge number of laboratory tests, often, but
not always, initiated in Primary Care but being the responsibility of the GP to take
appropriate follow-up actions. Many of the tests such as haematological investiga-
tions remain the same after many years whilst other tests are constantly emerging.
32 years after the first edition, this useful aide memoire reference book remains as
relevant as ever, not only for GP’s and practice nurses but also for any clinician
needing to interpret test results. Newer investigations such as FIB-4 testing in sus-
pected non-alcoholic fatty liver disease and proBNP commonly used in assessment
of heart failure and transglutaminase testing for coeliac disease are now included in
this revised seventh edition as well as updated guidelines for the use of HbA1c in
the diagnosis and monitoring of diabetes and the FIT test (Faecal Immunochemical
Test) instead of FOB testing.
After 33 years in NHS General Practice, I retired from the NHS but continue to
work in Occupational Health, specifically Aviation Medicine, having served a
9-year short service commission in the Royal Air Force before entering General
Practice. Whilst still dealing with clinical matters almost daily including referrals
and reports from other clinicians, I still have the same need to understand the rele-
vance of specific investigations, but I do not have the same access to laboratories
and clinicians whom I used to rely on for advice regarding test results. I, therefore,
enlisted the help of two current GP principals in practice to assist me in re-writing
this edition.
Dr Caroline Saxelby and Dr Niall McKay are both GPs involved in clinical
practice and the teaching and training of new entrants to GP and are aware of
good education in choosing and interpreting laboratory tests. Their help has
been invaluable, and the book would not have continued without their help,
particularly during the extremely challenging past 12 months due to Coronavi-
rus. I am grateful to all clinical and non-clinical persons who have kept our
health care system going during the Coronavirus epidemic and I hope that soon
there is a return to the values of our NHS enjoyed and benefitted by all before
Coronavirus.
vii
PREFACE TO THE SEVENTH EDITION
Within my current field of specialism, I am now more commonly involved with
abnormalities of ECGs in asymptomatic aircrew. I use well-researched and carefully
considered algorithms to follow up specific abnormalities and I have chosen to
share them in this edition. The section on ECG automated read-outs is not intended
as a clinical interpretation for a patient presenting in General Practice with a spe-
cific symptom but is a guide for what to do about common automated print-out
results in asymptomatic patients with reports such as bundle branch block or con-
duction disturbances. I am most grateful for the help and guidance from Dr Julia
Baron BM BS MD FRCP FESC.
I hope that you find the current edition useful in your daily practice.
Dr Michael McGhee
21st February 2021
AUTHOR BIOGRAPHIES
Dr Michael F McGhee LRCP (Lond) MRCS (Eng) MB BS (Lond) DRCOG
FRCGP Cert GAM DOcc Med
Mike qualified at St Mary’s Hospital London in 1975. He joined the RAF in 1972
and gained his MRCGP in 1979 and became a trainer with the RAF and spent time
at The Royal Army Medical College Millbank, London with the late Professor
Tommy Bouchier-Hayes RAMC. Together they organised education for military
GPs in training and often engaged the help of one of the Fathers of General Practice
the late John Fry CBE. Mike, after a short service commission, left the RAF to
enter General Practice in Castle Donington in 1981 where he became a trainer with
the Nottingham Vocational Training Scheme and an NHS appraiser. He has
co-authored A Guide to General Practice, Blackwell Scientific Publications, A Guide
to Infectious Diseases, Radcliffe Medical Press and Gynaecological Symptoms in Primary
Care, Blackwell Science Ltd. He retired from the NHS in 2014. During his time in
General Practice Mike also practised as an Aero-Medical Examiner for the UK
Civil Aviation Authority. He currently works part-time at East Midlands Airport
examining and certifying the fitness of Flight Crew and Air Traffic Controllers.
Dr Caroline Anne Saxelby BSc (Hons) MB ChB MRCGP PGCME
Caroline qualified at the University of Leeds Medical School, having previously
completed a BSc in medical microbiology. She is a part-time GP in a suburban
practice in Derby with a large elderly population. Her special interests are con-
traception and end of life care and she currently leads on both of these areas in
the practice. Since qualifying as a GP in 2008, she completed her Vocational
Training in Nottingham. She has also worked as a Contraception and Sexual
Health Staff doctor and was the Macmillan end of life lead for the Southern
Derbyshire CCG for a number of years until 2018. She is a GP Trainer having
completed her PGCME at De Montfort University, Leicester in 2010.
Dr Niall McKay MB ChB (Glasgow) MRCGP (Edinburgh)
Niall qualified in Glasgow in 1989. He is an experienced GP in Derby, having
worked in Primary Care in Scotland, England and Australia. He is a GP trainer
and Appraiser, and more recently PCN Clinical Director.
GLOSSARY
aCL anticardiolipin antibody
ACE angiotensin-converting enzyme
ACR albumin/creatinine ratio
AF atrial fibrillation
AFP alpha-fetoprotein
AIDS acquired immune deficiency syndrome
AL amyloid light-chain
ALOs Actinomyces-like organisms
ALP alkaline phosphatase
ALT alanine transferase
AKI acute kidney injury
AMA antimitochondrial antibody
Amp-C Amp C beta-lactamase producers
ANA antinuclear antibody
ANCA antineutrophil cytoplasmic antibody
Anti-CCP anti-cyclic citrullinated peptide
APC-R activated protein C resistance
APTT activated partial thromboplastin time
AS aortic stenosis
ASD atrial septal defect
ASO antistreptolysin-O
AST aspartate transferase
BMI body mass index
BNP B-type natriuretic peptide
BP blood pressure
CAA Civil Aviation Authority
CAD coronary artery disease
CGIN cervical glandular intraepithelial neoplasia
CHD coronary heart disease
CIN cervical intra-epithelial neoplasia
CK creatine kinase
