Testing Times! - Central Manchester University Hospitals - NHS ...

Testing Times!
Newsletter of the Clinical Biochemistry
Department Volume 1, Issue 1
Monday, 4 th July 2011
Central Manchester
University Hospitals
NHS Foundation Trust
In This Issue:
CRP 1
TFT 1
Minimum Retest
Intervals
Special points of interest:
This newsletter is the first in
a series which will address
rational use of Laboratory
Tests.
Our aim is to increase the
requesting of appropriate
Biochemistry tests, while
reducing the frequency of
inappropriate test requests.
An appropriate test is one
that leads to identifiable
benefit for patients and demonstrably
helps with clinical
management
2
Blood sampling 2
Infectious Enthusiasm: Clinicians’ Unquenchable Thirst
for C-Reactive Protein Tests
There seems to be a bottomless desire
from clinicians to measure serum C-
Reactive protein levels: we have seen a
doubling of requests every 3 years for
this test. Inappropriate requesting slows
down the service for all patients and is a
waste of resources. Please consider the
advice below when requesting CRP.
Lab Service Advice CRP01:
Minimum: Measure CRP at admission,
and then at 24 hours after admission
but not sooner.
Maximum: No greater frequency than
24h is required. In patients on antibiotics,
serial measurement on a 24 hourly
basis may help guide treatment.
CRP is a pentameric protein produced in
the liver in response to infection, trauma,
acute pancreatitis or burns. Its production
is stimulated by Interleukin-6 a cytokine
manufactured and secreted from
monocytes and macrophages.
The traditional indication for the test is
to identify the presence of inflammation,
determine severity and/or monitor response
to treatment.. In the conventional
inflammation setting, levels of CRP start
to rise 18 to 24 hours after the initiating
event, peak at 48 to 60 hours and return
to baseline levels at 5 to 7 days.
Tired All The Time: Thyroid Function Tests
In our laboratories Thyroid
Function Test means
Free Thyroxine (FT4) and
Lab Service Advice
TFT01:
It is extremely unlikely
that you will need to repeat
a TFT within 4 weeks.
Thyroid Stimulating Hormone
(TSH). Total (TT3)
or Free Tri-iodothyronine
The C-Reactive Protein Pentamer
Lab Service Advice CRP02:
Very high CRP: There is a high probability
of significant pathology when
CRP > 300 mg/L.
(FT3) is measured if there
are symptoms of thyrotoxicosis
and raised FT4
Lab Service Advice
TFT02:
Repeat TFT to monitor
T4 therapy at minimum
12 weeks intervals.

If you want blood, you got it!: We take too much blood from patients and
we do it too often!
Whenever we ask patients
about their hospital experience,
they make it clear to us
that laboratory tests are
their least favourite part of
the experience. This is especially
the case in children,
and needle-phobia caused by
repeated drawing of blood for
laboratory tests is a major
cause of anxiety and unhappiness.
on management. If the answer is ‘no’ then don’t do the test!
The right sample from the right patient at the right time.
Lab Service Advice PHLEB02:
When: When is the specific time it’s necessary to draw
blood for this test (e.g. 9am Cortisol)?
Why: Why perform the test? Is it for diagnosis, therapy
monitoring, prognosis or screening?
Every time we decide to do a blood test, we should carefully
consider whether the test is really needed and in
particular whether the result is likely to have an impact
Lab Service Advice PHLEB01:
How: How will a ‘positive’ change my patient’s management?
How will a ‘negative’ result change my patient’s
management? How will I use the result to
change my patient’s management plan?
What: What is the best test or tests? What is the
minimum volume of blood I need? What other tests can
I do on the same blood draw?
http://www.cmft.nhs.uk/
directorates/
deptlabmed/indexaz.asp
Please Sir, I Want Some More!
Below is the current consensus
for Minimum Retest Intervals for
Common Biochemistry Tests:
All tests can be measured at
greater frequency than indicated,
after discussion with one
of the Consultant Biochemists.
Test
Minimum Retest Interval
CRP
24h
eGFR
4 weeks
Iron
4 weeks
Ferritin
4 weeks
HbA1c
2 months
hCG pregnancy 2 days
Liver Function Tests 48 h
Lipids
4 weeks
Thyroid Function
Tests
4 to 10 weeks
Troponin T 4 days
Department of Clinical
Biochemistry
Clinical Sciences Building 3
Manchester Royal Infirmary
Oxford Road
Manchester M13 9WL
0161 901 5087