Recurring concern
Unreliable medication-specific blood-level monitoring
First reported 25 Jun 2014•Latest report 14 Jan 2026
What this concern includes
Includes failures of controls specifically dedicated to monitoring blood levels associated with a prescribed medicine, including guidance on testing thresholds or timing, arrangements for obtaining tests, interpretation of results and review of prescribing or monitoring practice. Includes the anchor's tinzaparin prescribing and blood-level monitoring concern and comparable failures concerning fluoxetine or clozapine levels.
Not included
- Excludes routine blood tests or biochemical monitoring where the assertion is not specifically about a medication-associated blood level.
- Excludes generic medication prescribing, administration, reconciliation, long-term review or medication-risk recognition failures when medication-specific blood-level monitoring is not the unsafe condition.
- Excludes failures concerning a clinical test performed for diagnosis or general disease monitoring rather than to monitor a medicine's level or medication-related toxicity.
- Excludes deficiencies limited to treatment response or clinical action after a medication level was reliably obtained, unless the monitoring process itself was also deficient.
- Reports
- 16
- Individual concerns
- 22
- Date range
- 2014–2026
- Stated actions
- 39
Distinct published reports
A report can raise multiple concerns
First to latest report issue date
Described in published responses
Reports over time
Reports over time
Reports about this concern issued each year.
* 2026 is projected from reports observed to 7 Sep 2026.
Most frequent recipients
Most frequent recipients
Reports about this concern sent to each recipient.
Concerns and responses across reports
Only concerns grouped under this recurring concern are included. Select any concern, action or position to view the source wording.
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Concerns raised1
Lack of national policy for regular clozapine blood plasma-level testing
This report raised 10 other concerns. They are not shown here because they do not form part of this recurring concern.
Responses linked to these concernsEach statement is shown once, even when linked to more than one concern.
Respondent positions A position is what a respondent says about the concern when they do not describe a specific action.2
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Position
The MHRA is responsible for medicine safety and will assess whether therapeutic drug monitoring supports safer clozapine use.
Stated by Nicola Blackwood
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Position
The NICE guideline surveillance team will consider whether guidance on clozapine plasma-level monitoring requires updating.
Stated by Nicola Blackwood
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Concerns raised1
Failure to complete quarterly kidney function and lithium-level monitoring
This report raised 2 other concerns. They are not shown here because they do not form part of this recurring concern.
Responses linked to these concernsEach statement is shown once, even when linked to more than one concern.
Actions described in response An action is something a respondent says it has done, is doing, or plans to do in response to the concern raised.1
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Action
Highlight lithium monitoring requirements to GPs and practices and remind them that current BNF and local CCG prescribing guidance is available.
Stated by NHS England
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Concerns raised1
Lack of routine clinical monitoring of Hydroxychloroquine levels
This report raised 8 other concerns. They are not shown here because they do not form part of this recurring concern.
Responses linked to these concernsEach statement is shown once, even when linked to more than one concern.
Respondent positions A position is what a respondent says about the concern when they do not describe a specific action.2
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Position
MHRA and NHS Improvement are responding separately to concerns about monitoring patients prescribed hydroxychloroquine.
Stated by Department of Health and Social Care
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Position
The MHRA has primary responsibility for monitoring Hydroxychloroquine toxicity and will provide the substantive response on this issue.
Stated by NHS England
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Concerns raised1
Delays in Heparin-level testing and result availability
This report raised 10 other concerns. They are not shown here because they do not form part of this recurring concern.
Responses linked to these concernsEach statement is shown once, even when linked to more than one concern.
Respondent positions A position is what a respondent says about the concern when they do not describe a specific action.1
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Position
The apparent 2-hour-37-minute APTT delay was actually 1 hour 20 minutes because the form was pre-prepared.
Stated by Barnsley Hospital NHS Foundation Trust
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Concerns raised1
Failure to ensure safe tinzaparin prescribing and blood-level monitoring
This report raised 1 other concern. They are not shown here because they do not form part of this recurring concern.
Responses linked to these concernsEach statement is shown once, even when linked to more than one concern.
Actions described in response An action is something a respondent says it has done, is doing, or plans to do in response to the concern raised.1
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Action
Complete consultation and obtain approval for the revised guideline on low molecular weight heparin prescribing and creatinine monitoring.
Stated by Hywel Dda University LHB
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Concerns raised1
Failure of sodium valproate blood test reference ranges to clearly indicate the therapeutic range
Responses linked to these concernsEach statement is shown once, even when linked to more than one concern.
No linked response statementsNo respondent-stated action or position is linked to these concerns in the published data.
Data last updated 7 September 2026