Optimising Blood Testing in Primary Care

Overview

This Guidelines summary signposts best-practice guidance and practical advice for optimising use of blood testing while maintaining clinical standards. It represents the prevailing best practice that should be followed day to day.

Key areas include:

• practical best-practice advice for primary care clinicians
• integrated care system (ICS)/CCG-level response to the acute shortage
• guidance on blood test requesting during the current shortage
• key primary care minimum retesting intervals guidance.

Practical Best Practice Advice for Primary Care Clinicians

Optimising Resource Use (Think twice, Check twice, Order once)

Think Twice

• Most laboratory parameters do not change rapidly—be familiar with the national guidance on minimum retesting intervals. For easy reference, some key examples relevant to primary care are included in Appendix 2 in the full guideline
• Note that in the context of the acute shortage of blood tubes, NHS England and NHS Improvement have provided additional guidance on reducing or deferring non-urgent blood tests
• Other bodies have also issued relevant guidance (for example, the National Blood Transfusion Committee [NBTC])
• Before requesting blood tests, consider if the test is essential for management and adheres to clinical guidance:
  • long-term condition/chronic disease monitoring and reviews —see Appendix 2 in the full guideline
    • note that full blood count, liver function tests (LFTs), and thyroid function tests are rarely required for most routine reviews
  • coagulation—rarely required as a routine test in primary care:
    • international normalised ratio (INR)—point-of-care testing (POCT) should be used for INR monitoring if available (and lab confirmation of POCT results is not required unless equipment malfunction is suspected). POCT testing should follow the Medicines and Healthcare products Regulatory Agency guidance on training quality and maintenance
  • D-dimer:
    • D-dimer testing for venous thromboembolism (VTE) should be done in accordance with NICE guidance on Venous thromboembolic diseases: diagnosis, management and thrombophilia testing, taking into account the clinical likelihood of VTE and the availability and timing of testing
    • for people in whom deep vein thrombosis (DVT) is likely (Wells score of 2 or more), a D-dimer test should be done if an initial ultrasound scan is negative or cannot be obtained within 4 hours and further NICE guidance followed
    • for people in whom DVT is unlikely (Wells score of 1 or below), a D-dimer test should be done and further NICE guidance followed
    • for people in whom pulmonary embolism is unlikely (Wells score of 4 or below), a D-dimer test should be done and further NICE guidance followed
    • D-dimer testing should not be done in patients in whom pulmonary embolism is likely (Wells score greater than 4):
      • D-dimer testing should only be done in patients in whom DVT is likely (Wells score of 2 or more) in accordance with the NICE guidance
      • D-dimer POCT should be considered where laboratory testing is not immediately available (for example, in the primary care/community setting if not referring to same-day emergency care or the emergency department) and does not need to be confirmed by lab sample testing
  • Inflammatory markers:
    • inflammatory markers (for example, C-reactive protein [CRP] and erythrocyte sedimentation rate [ESR]) should only be requested if there is a clinical indication and the result will change management
    • outside of specific rheumatological indications (for example, temporal arteritis/polymyalgia rheumatica), ESR adds no new information over CRP and there is therefore no need to request both tests
    • it is suggested that, in the absence of rheumatology advice or a specific clinical indication, CRP alone is preferable
    • also note that in most cases ESR can be tested on the same ethylenediaminetetraacetic acid (EDTA) sample as FBC (and so an additional sample tube is not required)
  • Consider using POCT for glucose, INR, and haemoglobin where available and appropriately quality assured.

Check Twice

• Double-check if the test was recently done in secondary care—does it need to be repeated?
  • To support this, ICSs/CCGs are asked to ensure that clinicians in both primary and secondary care have access to the results of tests conducted for their patients in all care settings.

Order Once

• Before requesting blood tests check if the patient is due another test and whether the tests can be combined:
  • for example, if a patient is due a chronic kidney disease review and there is concern about LFTs, ensure both tests are done together, using a single blood tube for all the biochemistry tests
• Add-on tests—check if the test can be added on to a recent (past days to week) sample. Do not rebleed your patient without first checking:
  • your local lab service should have a contact number for add-on tests—ensure all clinical staff are aware of this
  • ICSs/CCGs are asked to promote awareness of the potential to add-on blood tests within primary and community care, including by providing the direct dial number to contact the relevant lab, and, where possible, indicative timescales/sample ages within which add-on tests are possible.

Clinical Information Resources

How Often Should Blood Tests Be Repeated?

• Most blood tests do not need to be frequently repeated in primary (or acute) care. National guidance on minimum retesting intervals, defined as the minimum time before a test should be repeated, based on the properties of the test and the clinical situation in which it is used, is available.

Which Samples Should Be Sent in Which Blood Tubes, and Which Samples Can Be Combined in One Tube?

• Refer to your local blood tube guide and look out for new information on tube substitutions and suggestions for combining multiple tests in a single tube—only substitute or combine samples as advised by your local laboratory
• The NHS suggests that ICSs/CCGs work with their local labs to develop an easy reference, up-to-date table that: reflects local lab policies; shows blood tube types in use and which samples can be sent in which tubes; and gives clear advice on tube substitutions, samples that can be combined, and any specific instructions. This should be distributed to all relevant clinical areas.

Blood Sample Collection and Dispatch

• When taking specimens please only collect the number of tubes stated by order comms or on the request form (do not send an extra tube just in case):
  • where samples can be combined, only send a single tube:
    • this may be the case, for example, for: HbA_1c and FBC (a single EDTA tube), biochemistry and immunology or virology samples (a single serum tube)
    • local lab practices vary, however, so it is important to follow relevant local guidance
    • such combinations should be advised by your lab and disseminated by ICSs/CCGs to ensure all relevant clinicians are aware
• Ensure that good phlebotomy technique is used:
  • good preparation, trained phlebotomists, order of draw, adequate filling of blood tubes—this will help avoid haemolysis or inadvertent sample activation
• Ensure correct labelling (particularly when hand-writing labels, such as for transfusion samples—please refer to local laboratory requirements for transfusion sample labelling)
• Ensure all tubes and request forms are double checked for errors before they are dispatched to the laboratory to avoid wasting tubes on rejected samples.

ICS/CCG-level Response to the Acute Shortage

Referral Pathways and Protocols

• The NHS recommends that ICSs/CCGs review referral pathways and work with local referral services to rationalise local pre-referral work-up requirements:
  • the NHS suggests that ICSs/CCGs review clinical referral pathways requiring blood tests to agree with the referral services which test requirements can be safely omitted or deferred at the point of referral
  • this might include, for example: 2-week wait (2WW), memory clinic, haematology referrals, or recurrent miscarriage clinics
• Work with acute trusts to ensure that requests for follow-up blood testing in primary care are rationalised:
  • the NHS suggests that ICSs/CCGs review with acute trusts requests for follow-up blood testing after discharge to the community with a view to rationalising these in line with national minimum retesting intervals guidance
  • this might include, for example: requests and indications for monitoring of renal function; monitoring of therapeutic drug level and associated complications (including psychiatric drugs); or routine postoperative follow-up blood tests (such as post-bariatric surgery routine follow-up bloods including for micronutrients such as selenium, copper, or zinc). 

Stock Optimisation

• Review all the recommendations provided and aim to reduce your use of blood tubes where appropriate
• Stock rotate your tubes to avoid tubes being wasted by going out of date
• Do not stockpile—continue your normal ordering, little and often to avoid any disruption to overall supplies
• If running short on stock, contact your CCG, laboratory, or usual supplier—usually that is Primary Care Support England. If the situation is not resolved by contacting the supplier, then local mutual aid should be explored via your CCG
• Engage fully in providing stocktake data when this is requested: the number of tubes held centrally and at individual GP practice or other sites. This will help ensure that everyone has adequate supply for urgent care
• Be prepared for calls to substitute specific tube orders for alternatives and requests to remove from use tubes which are in short supply, to enable fair distribution to other sites.

Guidance on Blood Test Requesting During the Current Acute Shortage

Patient Communication and Shared Decision-making

• Changes to patient testing should be made in consultation with individual patients. Make it clear that deferred tests will be carried out in the future where appropriate
• As part of conversations with patients, make it clear that routine tests will be deferred only where it is clinically safe to do so
• Be open and honest with patients about the supply issue. Deferral of testing is not the practice’s fault.

Indications for Blood Testing During the Period of Acute Shortage

• Tests that are urgent and clinically indicated should not be delayed
• In conjunction with the NHS England and NHS Improvement guidance, the following may be considered important indications for not deferring testing during the shortage period:
  • a concern for cancer and making a 2WW referral
  • acute disease where the lack of primary care confirmation would mean that the only other route is to attend emergency department/admit
  • monitoring of disease-modifying antirheumatic drugs (DMARDs) and lithium
  • urea and electrolytes in advance of planned contrast computed tomography if not tested in the previous 3 months
  • bloods that are extremely overdue and/or essential for safe prescribing of medication
  • bloods that are essential for monitoring a new or existing condition
  • vulnerable patients (with severe mental illness, a learning difficulty or dementia) if this will change management or where there is a risk that the patient will not attend again
  • antenatal serology/fetal anomaly blood tests.

Guidance Relating to Specific Tests During the Blood Tube Shortage

• Advice on Quality and Outcomes Framework (QOF) blood tests:
  • NHS England and NHS Improvement have provided additional guidance specifically relating to testing during the period of acute shortage
  • some QOF indicators relate to testing (see Appendix 1 in the full guideline)
  • full guidance on QOF indicators is available
• Vitamin D testing:
  • too much vitamin D testing is carried out routinely. The NHS recommends that it is stopped except in the very exceptional circumstances set out in NICE CKS guidance
  • examples of people who do not need routine testing for vitamin D:
    • asymptomatic people at higher risk of vitamin D deficiency, but they should be advised on the need for maintenance dose vitamin D supplementation
    • people with osteoporosis and fragility fracture who are treated with vitamin D supplements and an oral antiresorptive agent
  • complex nutritional patients, such as those on home parenteral feeding, should have their annual vitamin D checks delayed unless clinically urgent and/or directed by the secondary care team
• Routine wellness screening:
  • routine wellness screening (for example, for prediabetes or dyslipidaemia) is not a priority and especially if patients are in the acute phase of any illness
  • however, certain acute tests should be assessed as appropriate, and all acute patients assessed appropriately when recovered. Alternative evidence-based interventions to promote wellness include Making Every Contact Count, nutrition, exercise, and Moving Medicine
• Allergy testing:
  • allergy testing is not a priority at this time unless there are overriding clinical indications
• Routine infertility testing:
  • routine infertility testing should generally be deferred until the supply disruption has been resolved, with the exception of patients over 35 years of age in consultation with the individual patient
  • where the patient is under 35 and there is a known cause of infertility, consider whether infertility testing can be delayed or not
  • if a patient of any age is undertaking fertility treatment and requires monitoring of bloods, tests should not be delayed
• Thyroid tests:
  • annual monitoring for thyroid replacement therapy can be deferred for an additional 3 months if stable. If dose has changed, then wait 2 months before repeating
  • routine screening in asymptomatic patients should only be repeated after 3 years
• Lipid tests:
  • lipid levels for patients on statins for primary prevention do not require monitoring (except to confirm initial compliance/effect, for example, after 3 months)
  • in high-risk patients/those on a statin for secondary prevention, annual testing is advised
• Monitoring of DMARDs in rheumatology patients:
  • the following provides a suggested approach to modifying DMARD monitoring protocols in the context of the acute shortage of blood tubes/testing capacity. Local policies should be followed in discussion with appropriate rheumatology colleagues
  • patients who have been on treatment for less than 12 months and/or on their current dose for less than 6 weeks should continue to be monitored as per the standard shared care agreement schedule
  • for patients under shared care who have been on treatment for over 12 months and where their last two blood monitoring tests have been normal and current dose has been stable for 3 months, refer to Table 1
  • no monitoring is required for patients on sulfasalazine after 1 year, based on current shared care schedule. For patients on treatment for less than 1 year, 3-monthly monitoring should continue.

Table 1: Suggested Modified DMARD Monitoring Schedule

• Blood transfusion samples (group and screen):
  • the NBTC has produced guidance relevant to transfusion-related testing and laboratory practices during the period of acute shortage
• Antenatal testing:
  • antenatal serology and fetal anomaly blood tests are time-sensitive and should not be delayed
• Blood-borne virus screening in high-risk populations:
  • screening for HIV and hepatitis B and C in high-risk groups should be done in accordance with the British HIV Association and NICE guidance. These are treatable conditions and delayed diagnosis contributes to poor outcomes and health inequalities
  • care should be taken to minimise unnecessary repeat testing, however, especially if a previous positive result has been obtained (for example, HIV or hepatitis)
• Other tests:
  • blood tests may be deferred in the case of fatigue, post dual-energy x-ray absorptiometry osteoporosis blood tests, or amiodarone monitoring (if assessed in the previous 12 months)
  • nutritional and trace elements—check with laboratory before taking samples to ensure the correct tubes are used.

For a list of QOF indicators related to testing, refer to the full guideline.