Best practice in primary care pathology: review 9.

This ninth best-practice review examines two series of common primary care questions in laboratory medicine: (i) potassium abnormalities and (ii) venous leg ulcer microbiology. The review is presented in question-and-answer format, referenced for each question series. The recommendations represent a précis of guidance found using a standardised literature search of national and international guidance notes, consensus statements, health policy documents and evidence-based medicine reviews, supplemented by MEDLINE EMBASE searches to identify relevant primary research documents. They are not standards but form a guide to be set in the clinical context. Most are consensus rather than evidence-based. They will be updated periodically to take account of new information.

Best practice in primary care pathology: review 8.

This eighth best practice review examines four series of common primary care questions in laboratory medicine: (i) sodium abnormalities; (ii) faecal occult blood testing; (iii) warfarin management; and (iv) sputum cytology in diagnosis of bronchopulmonary malignancy. The review is presented in question-answer format, referenced for each question series. The recommendations represent a précis of guidance found using a standardised literature search of national and international guidance notes, consensus statements, health policy documents and evidence-based medicine reviews, supplemented by Medline Embase searches to identify relevant primary research documents. They are not standards but form a guide to be set in the clinical context. Most are consensus rather than evidence-based. They will be updated periodically to take account of new information.

Best practice in primary care pathology: review 7.

This seventh best-practice review examines four series of common primary care questions in laboratory medicine: (1) blood count abnormalities 2; (2) cardiac troponins; (3) high-density lipoprotein cholesterol; and (4) viral diseases 2. The review is presented in a question-answer format, with authorship attributed for each question series. The recommendations are a précis of guidance found using a standardised literature search of national and international guidance notes, consensus statements, health policy documents and evidence-based medicine reviews, supplemented by Medline Embase searches to identify relevant primary research documents. The recommendations are not standards, but form a guide to be set in the clinical context. Most are consensus based rather than evidence based. They will be updated periodically to take account of new information.

Best practice in primary care pathology: review 6.

This sixth best practice review examines four series of common primary care questions in laboratory medicine: (1) laboratory monitoring in hypertension and heart failure abnormalities; (2) markers of inflammatory joint disease; (3) laboratory investigation of chronic diarrhoea; and (4) mumps and chickenpox. The review is presented in question-answer format, referenced for each question series. The recommendations represent a precis of guidance found using a standardised literature search of national and international guidance notes, consensus statements, health policy documents and evidence-based medicine reviews, supplemented by Medline Embase searches to identify relevant primary research documents. They are not standards but form a guide to be set in the clinical context. Most are consensus based rather than evidence based. They will be updated periodically to take account of new information.

Liquorice and soy sauce, a life-saving concoction in a patient with Addison's disease.

Addison's disease is a relatively common disorder to endocrinologists, but is rare and potentially fatal when presenting acutely. Treatment now involves replacement of glucocorticoids and mineralocorticoids with synthetic compounds, although historically patients took common salt and plant-based preparations. We describe the case of a 42-year-old woman who self-treated undiagnosed Addison's disease for several years with soy sauce and liquorice sticks. She presented with a four-week history of decreased energy, malaise and postural dizziness. Our patient described an unusual diet of liquorice sticks and soy sauce, consuming around 46 g of salt per week. There was a family history of Type 1 diabetes mellitus. Physical examination was unremarkable, although subsequent investigation confirmed Addison's disease. Liquorice provided glycyrrhizic acid and glycyrrhetinic acid, which act on 11-beta hydroxysteroid dehydrogenase enzymes. In this case, the net effect was potentiation of glucocorticoid action on renal mineralocorticoid receptors in the context of failing adrenocortical steroid production. The case highlights the importance of taking a dietary history to aid diagnosis.

Best practice in primary care pathology: review 5.

This fifth best practice review examines three series of common primary care questions in laboratory medicine: (1) minor liver function test abnormalities; (2) laboratory monitoring of patients receiving lithium; and (3) investigation of possible venous thromboembolism. The review is presented in question-answer format, referenced for each question series. The recommendations represent a precis of guidance found using a standardised literature search of national and international guidance notes, consensus statements, health policy documents and evidence-based medicine reviews, supplemented by Medline Embase searches to identify relevant primary research documents. They are not standards but form a guide to be set in the clinical context. Most are consensus-based rather than evidence-based. They will be updated periodically to take account of new information.

Best practice in primary care pathology: review 3.

This best practice review examines four series of common primary care questions in laboratory medicine: (i) "minor" blood platelet count and haemoglobin abnormalities; (ii) diagnosis and monitoring of anaemia caused by iron deficiency; (iii) secondary hyperlipidaemia and hypertriglyceridaemia; and (iv) glycated haemoglobin and microalbumin use in diabetes. The review is presented in question-answer format, referenced for each question series. The recommendations represent a précis of guidance found using a standardised literature search of national and international guidance notes, consensus statements, health policy documents and evidence-based medicine reviews, supplemented by Medline Embase searches to identify relevant primary research documents. They are not standards, but form a guide to be set in the clinical context. Most of the recommendations are based on consensus rather than evidence. They will be updated periodically to take account of new information.

Best practice in primary care pathology: review 4.

This fourth best practice review examines four series of common primary care questions in laboratory medicine are examined in this review: (1) safety monitoring for three common drugs; (2) use of prostate-specific antigen; (3) investigation of vaginal discharge; and (4) investigation of subfertility. The review is presented in question-answer format, referenced for each question series. The recommendations represent a precis of the guidance found using a standardised literature search of national and international guidance notes, consensus statements, health policy documents and evidence-based medicine reviews, supplemented by Medline Embase searches to identify relevant primary research documents. They are not standards but form a guide to be set in the clinical context. Most of them are consensus based rather than evidence based. They will be updated periodically to take account of new information.

Methodology for constructing guidance.

Although guidance exists for the use of many laboratory tests in a wide range of clinical situations, this guidance is spread among a range of literature sources, and is often directed at laboratory specialists rather than test users. Individual general practices display large variations in standardised test requesting, yet much of their testing activity involves a relatively small range of tests. This paper describes a methodological approach to review the available evidence and guidance and to extract relevant primary research work to examine a range of testing scenarios in general practice, with the aim of formulating guidance based on the best available evidence or consensus opinions.

Best practice in primary care pathology: review 1.

This first best practice review examines four series of common primary care questions in laboratory medicine, namely: (i) measurement and monitoring of cholesterol and of liver and muscle enzymes in patients in the context of lipid lowering drugs, (ii) diagnosis and monitoring of vitamin B12/folate deficiency, (iii) investigation and monitoring of paraprotein bands in blood, and (iv) management of Helicobacter pylori infection. The review is presented in a question-answer format, referenced for each question series. The recommendations represent a précis of guidance found using a standardised literature search of national and international guidance notes, consensus statements, health policy documents, and evidence based medicine reviews, supplemented by MEDLINE EMBASE searches to identify relevant primary research documents. They are not standards but form a guide to be set in the clinical context. Most are consensus rather than evidence based. They will be updated periodically to take account of new information.

Inequalities of primary care microbiology testing between hospital catchment areas.

AIMS: To compare differences in microbiology testing activity between general practices within and between five hospitals in two National Health Service (NHS) regions in England. METHODS: Retrospective capture of standardised microbiology testing activity from the laboratory computer databases. Six equivalent tests were identified and compared. Data were obtained for 174 general practices in eight primary care groups, served by two NHS hospital trusts and three public health laboratories. The total catchment population was 1,180,000 people. Comparative test activities were displayed graphically and differences in median test activity and the hospital activity distributions were examined by the Wilcoxon signed rank test. RESULTS: Median testing activity differed by 200% (urine) to 800% (wound swabs) between the trusts that performed the highest and the lowest number of tests, and from 300% to 1900% between the top and bottom 10% activity bands of general practices. Large and significant differences were found between the hospitals, irrespective of whether they belonged to the same trust, and irrespective of their geographical location. CONCLUSIONS: Large differences in microbiology testing exist within individual trust catchment areas in primary care, and there are also considerable differences between trusts. These inequalities may also introduce a selection bias into epidemiological and antibiotic resistance surveillance. This indicates a widespread need to examine and deal with the reasons responsible for these differences.

Is clinical practice variability the major reason for differences in pathology requesting patterns in general practice?

AIMS: To examine whether variations in pathology test requesting between different general practices can be accounted for by sociodemographic or other descriptive indicators of the practice. METHOD: This was a comparative analysis of requesting patterns across a range of pathology tests representing 95% of those requested in general practice, in 22 general practices in a single district, serving a population of 165 000. Spearman correlation coefficients were calculated and both the top and bottom fifths of activity were displayed graphically to detect trends at the extremes of the ranges. RESULTS: The proportion of women of childbearing age, median practice Townsend scores, or the existence of specialist miniclinics within the practice did not have a demonstrable impact on requesting patterns. A weak correlation was found between the proportion of elderly patients and creatinine/electrolyte testing but not for the other two tests examined for this patient group. CONCLUSIONS: The large differences observed in general practice pathology requesting probably result mostly from individual variation in clinical practice and are therefore potentially amenable to change.

Appropriateness of test use in pathology: a new era or reinventing the wheel?

Pathology has struggled to define and implement changes to improve requesting practices, yet, with the increasing transfer of care from secondary to primary care, our workloads are increasing out of proportion to health care activity. Conversely, some tests appear to be considerably under-used by some general practitioners. Aspects of service reconfiguration such as rationalization of low-volume testing and joint equipment and reagent procurement may release some savings, although any such financial benefits are likely to be quickly nullified by the continued rise in activity and do not contribute to quality of test use. With very large differences between general practices in their use of pathology tests, this review looks at methods for changing pathology requesting activity and calls for involvement from professional organizations to support such initiatives.

Demand management and test request rationalization.

Demand for laboratory testing is increasing disproportionately to medical activity, and the tests involved are becoming increasingly complex. When this phenomenon is seen in parallel with declining teaching of laboratory medicine in the medical curriculum, a need emerges to manage demand to avoid unnecessary expenditure and improve the use of laboratory services: 'the right test in the right patient at the right time.' Various methods have been tried to manage demand, with success depending on the medical context, type of health service and preintervention situation. Because many factors contribute to demand, and the different settings in which these exist, it is not realistic to meta-analyse the studies and we are limited to trying to identify trends in results in particular situations. The studies suggest that education combined with facilitating interventions, such as feedback, prompts and changes to laboratory request forms are the most successful. From the perspective of a whole health service, it is important that results are not exaggerated by assessing benefits in terms of total rather than marginal cost. It would be desirable, although difficult, to include the impact on downstream clinical activity caused or avoided by the interventions. Advances in information and web technology may make the elusive goal of achieving substantial demand control more achievable.

Best practice in primary care pathology: review 14.

This 14th best practice review is the second of a pair that examines tumour marker requesting primary care situations. This review considers carbohydrate antigen 125, α-fetoprotein and human chorionic gonadotropin. It is presented in question-answer format, referenced for each question. The recommendations represent a précis of guidance found using a standardised literature search of national and international guidance notes, consensus statements, health policy documents and evidence-based medicine reviews, supplemented by MEDLINE EMBASE searches to identify relevant primary research documents. They will be updated periodically to take into account new information.

Best practice in primary care pathology: review 13.

This 13th best practice review examines tumour marker requesting primary care situations. The review is presented in question--answer format, referenced for each question. This review considers carcinoembryonic antigen carbohydrate antigen 15-3 (Ca15-3) and carbohydrate antigen 19-9 (Ca19-9). The recommendations represent a précis of guidance found using a standardised literature search of national and international guidance notes, consensus statements, health policy documents and evidence-based medicine reviews, supplemented by MEDLINE EMBASE searches to identify relevant primary research documents. They will be updated periodically to take account of new information.

Best practice in primary care pathology: review 12.

This twelfth best practice review examines four series of common primary care questions in laboratory medicine: (i) antiepileptic drug monitoring; (ii) infectious diarrhoea; (iii) methicillin resistant Staphylococcus aureus; and (iv) brain natriuretic peptide. The review is presented in question-answer format, referenced for each question series. The recommendations represent a précis of guidance found using a standardised literature search of national and international guidance notes, consensus statements, health policy documents and evidence-based medicine reviews, supplemented by MEDLINE EMBASE searches to identify relevant primary research documents. They are not standards but form a guide to be set in the clinical context. Most are consensus rather than evidence-based. They will be updated periodically to take account of new information.

Intravenous fluid therapy - an under-recognized patient safety opportunity.

Inappropriate fluid regimens are rarely documented as being responsible for patient harm, although there is considerable circumstantial evidence to suggest that fluid overload may be a considerably under-estimated source of patient morbidity and mortality. The GIFTASUP fluid management guidelines published in 2008 offer a valuable opportunity to consider a more standardised approach to fluid management, possibly in the context of developing routine hospital services to support good practice.

What is a significant difference between sequential laboratory results?

The uncertainty of a numerical laboratory result can be masked by the fact that the laboratory reports an absolute number, whereas users have limited knowledge of the confidence interval of the result. Interpretation of laboratory tests is in reality therefore an inexact science, a balance between clinical context and the likely relevance of a laboratory result. This review considers the factors which contribute to result variability and examines the implications for interpreting differences between sequential laboratory results. It offers suggestions to deal with a problem which has not yet been much addressed in routine practice. The examples used are restricted to the discipline of clinical biochemistry, although the issues and principles apply to numerical (and indeed qualitative) results in other disciplines. Laboratories could provide more guidance on the likelihood of a result being significant to assist users. There is a need for discussion about how this is best done, and compatible with electronic result delivery. Options for providing this information are considered.