APFCB Masterclass in Interpretative Commenting

Thyroid function test results

Sam Vasikaran
PathWest-Laboratory Medicine WA
Perth, Western Australia

ASIA-PACIFIC FEDERATION FOR CLINICAL

BIOCHEMISTRY AND LABORATORY MEDICINE
 Today’s Agenda

1. Interpretative commenting in Clinical Chemistry

 What, Why, How

2. Series of common TFT results

 Interpretative comments
What?
 The organisational model
for Laboratory Medicine

The primary laboratory

operations

Manufacturing processes

Patient preparation

Sample collection

Testing

Report transmission

Efficiency

Blanckaert N. Clin Chem Lab Med 2010;48(7):919–25

 The organisational model
for Laboratory Medicine

The primary laboratory Value adding

operations
knowledge application processes
Manufacturing processes

Appropriate test selection

Result interpretation

→ Impact on health and outcome

Effectiveness

Blanckaert N. Clin Chem Lab Med 2010;48(7):919–25

 The organisational model for
Laboratory Medicine of the 21st century

 knowledge application processes

 Will be the primary activities

 test manufacturing processes

 Will be supporting activities

 Clinical scientists and pathologists that fail to be perceived by

clinical colleagues as medical value contributors will be at risk

 Blanckaert N. Clin Chem Lab Med 2010;48(7):919–25

 There must be advice readily available at all times to
explain to requesting clinicians what reports mean if that
is not clear to them

 Clinical Pathology Accreditation (UK) standard D4 (1992)

 A test request is a referral for specialist opinion

 Reports be supported by comments where appropriate

 RCPA (UK) Chemical Pathology Guidelines

Why?
 Survey of junior doctors’ knowledge in clinical biochemistry

Khromova K, Gray T. Ann Clin Biochem 2008;45:33–8

 Not confident requesting or interpreting

 Mg, PO4, PTH, short Synacthen tests, and urine Na and osmolality

 Confident requesting, but less confident in interpreting

 LFTs, proteins and haematinics

 Some ‘very confident’ in requesting tests they are ‘not confident’ in

interpreting.

 Unsure of effects of common problems like haemolysis on results.

How helpful are thyroid function test comments?
A survey of doctors and nurses (UK)
Barlow IM. Ann Clin Biochem 2008;45(1):88-90

Most general practitioners and nurses found that

thyroid function test interpretative comments were helpful
 Questionnaire to junior doctors in our hospital
on interpretative comments in lab reports

Do you find the interpretative comments

attached to the following results in this hospital useful?

Yes No Not
noticed
Thyroid function tests 74% 17% 9%
Iron Studies 87% 13%
Glucose tolerance tests 78% 22%
Synacthen test 78% 22%
 Can addition of interpretative comments to lab reports
influence outcome?
Kilpatrick ES. Ann Clin Biochem 2004; 41: 227–229

 A study of TFT requests by GPs

 for 8281 patients taking thyroxine.

 Under-replacement of thyroxine (defined as a raised TSH)

was commented on in the biochemical report by the lab

 In the years following introduction of comments, the

proportions of samples with a raised TSH were
significantly reduced (P<0.0001).
How?
 Interpretation should be provided by an appropriately
qualified person

 Comments more appropriate for GPs and junior doctors

 but not always so - Ascertain user requirements

 Over-interpretation may be misleading

 RCPA (UK) Chemical Pathology Guidelines

 RCPath (UK) guidelines for provision of
interpretative comments on biochemical reports

Comments might be appropriate when:

 a management / treatment decision is indicated by results
 a result is unexpected
 a specific question has been posed but it is not obvious whether
the results provide the answer
 a clinician has requested a test with which they are unlikely to be
familiar
 Possible components of
an interpretative comment

 The absence or presence of an abnormality and

its degree or severity

 Possible implications of abnormality

 diagnosis, prognosis, change in status etc

 Suggested action/follow-up
 Pitfalls to be avoided

 Restating the obvious

 Commenting on reports to a doctor who does not want them

 Commenting on speciality reports to a specialist in the field

 Telling the clinician how to do his/her job

 Suggestion for invasive (non-laboratory) investigations

 Communication with clinicians

 To:
 Agree on test protocols & diagnostic criteria
 Get feedback about the comments

 Unusual and interesting results could be triggers for direct (verbal)

communication and discussion
Common TFT results
 Patient: 28-year-old female

 Patient Location: General Practice

 Clinical Notes on Request Form: Lethargy

 TFT s

 TSH 0.67 mU/L (0.50–4.0)

 Free T4 16 pmol/L (10–20)

 Patient: 28-year-old female

 Patient Location: General Practice

 Clinical Notes on Request Form: Lethargy

 TFT s

 TSH 0.67 mU/L (0.50–4.0)

 Free T4 16 pmol/L (10–20)

 Comment:
Normal T4 and TSH are consistent with an euthyroid state.
 Patient: 28-year-old female

 Patient Location: General Practice

 Clinical Notes on Request Form: Lethargy

 TFT s

 TSH 0.67 mU/L (0.50–4.0)

 Patient: 28-year-old female

 Patient Location: General Practice

 Clinical Notes on Request Form: Lethargy

 TFT s

 TSH 0.67 mU/L (0.50–4.0)

 Comment
Normal TSH is consistent with an euthyroid state.
 Patient: 28-year-old female

 Patient Location: General Practice

 Clinical Notes on Request Form: Lethargy

 TFT s

 TSH 0.67 mU/L (0.50–4.0)

 Free T4 8 pmol/L (10–20)

 Patient: 28-year-old female

 Patient Location: General Practice

 Clinical Notes on Request Form: Lethargy

 TFT s

 TSH 0.67 mU/L (0.50–4.0)

 Free T4 8 pmol/L (10–20)

 Comment
A mildly reduced FT4 with a normal TSH may be due
to non-thyroidal illness or pituitary hypothyroidism.
 Patient: 57-year-old female

 Patient Location: General Practice

 Clinical Notes on Request Form: Weight gain

 TFT s

 TSH 7.4 mU/L (0.50–4.0)

 Patient: 57-year-old female

 Patient Location: General Practice

 Clinical Notes on Request Form: Weight gain

 TFT s

 TSH 7.4 mU/L (0.50–4.0)

 Comment
Mildly increased TSH may be found in patients with subclinical
hypothyroidism or sick euthyroid syndrome.
Suggest measurement of FT4, TSH and TPO antibodies in 6 weeks.
 Patient: 57-year-old female

 Patient Location: General Practice

 Clinical Notes on Request Form: Weight gain

 TFT s

 TSH 7.4 mU/L (0.50–4.0)

 Free T4 13 pmol/L (10–20)

 Patient: 57-year-old female

 Patient Location: General Practice

 Clinical Notes on Request Form: Weight gain

 TFT s

 TSH 7.4 mU/L (0.50–4.0)

 Free T4 13 pmol/L (10–20)

 Comment
Mild increase in TSH with a normal fT4 may be found in patients
with subclinical hypothyroidism or non-thyroidal illness.
 Patient: 77-year-old male

 Patient Location: General Practice

 Clinical Notes on Request Form: Routine check

 TFT s

 TSH 4.5 mU/L (0.50–4.0)

 Free T4 15 pmol/L (10–20)

 Patient: 77-year-old male

 Patient Location: General Practice

 Clinical Notes on Request Form: Routine check

 TFT s

 TSH 4.5 mU/L (0.50–4.0)

 Free T4 15 pmol/L (10–20)

 Comment
Mildly increased TSH with a normal fT4 can be seen in the
euthyroid elderly
 Patient: 62-year-old female

 Patient Location: General Practice

 Clinical Notes on Request Form: Constipation

 TFT s

 TSH 14.0 mU/L (0.50–4.0)

 Free T4 11 pmol/L (10–20)

 Patient: 62-year-old female

 Patient Location: General Practice

 Clinical Notes on Request Form: Constipation

 TFT s

 TSH 14.0 mU/L (0.50–4.0)

 Free T4 11 pmol/L (10–20)

 Comment
A moderately increased TSH with a normal fT4 is consistent with
(mild) primary hypothyroidism
 Patient: 24-year-old female

 Patient Location: Obstetric clinic

 Clinical Notes : POA 12/40

 TFT s

 TSH 0.05 mU/L (0.50–4.0)

 Free T4 13 pmol/L (10–20)
 Patient: 24-year-old female

 Patient Location: Obstetric clinic

 Clinical Notes : POA 12/40

 TFT s

 TSH 0.05 mU/L (0.50–4.0)

 Free T4 13 pmol/L (10–20)

 Comment

TSH reference intervals in pregnancy

1st trimester 0.02 – 2.5
2nd and 3rd trimester 0.30 – 3.0
 Patient: 31-year-old female
 Patient Location: General Practice

 Clinical Notes : Trying for a baby

 TFT s

 TSH 4.6 mU/L (0.50–4.0)

 Free T4 13 pmol/L (10–20)
 TPO Antibodies 33 kU/L (< 6 )
 Patient: 31-year-old female
 Patient Location: General Practice

 Clinical Notes : Trying for a baby

 TFT s

 TSH 4.6 mU/L (0.50–4.0)

 Free T4 13 pmol/L (10–20)
 TPO Antibodies 33 kU/L (< 6 )

 Comment
The mildly increased TSH and raised TPO antibodies indicate subclinical
hypothyroidism due to autoimmune thyroid disease.
Suggest confirm subclinical hypothyroidism by repeat testing. Poor
pregnancy outcomes have been described in women with a raised TSH.
If raised TSH confirmed, consider thyroxine replacement.
 Patient: 54-year-old male
 Patient Location: General Practice

 Clinical Notes : Feeling very tired

 TFT s

 TSH 0.02 mU/L (0.50–4.0)

 Free T4 18 pmol/L (10–20)
 Patient: 54-year-old male
 Patient Location: General Practice

 Clinical Notes : Feeling very tired

 TFT s

 TSH 0.02 mU/L (0.50–4.0)

 Free T4 18 pmol/L (10–20)

 Comment
The suppressed TSH and normal fT4 are consistent with subclinical
hyperthyroidism.
Suggest measure fT3.
 Patient: 54-year-old male
 Patient Location: General Practice

 Clinical Notes : Hyperthyroid?

 TFT s

 TSH 0.02 mU/L (0.50–4.0)

 Free T4 18 pmol/L (10–20)
 fT3 6.1 pmol/L (3.0-5.5)
 Patient: 54-year-old male
 Patient Location: General Practice

 Clinical Notes : Hyperthyroid?

 TFT s

 TSH 0.02 mU/L (0.50–4.0)

 Free T4 18 pmol/L (10–20)
 fT3 6.1 pmol/L (3.0-5.5)

 Comment
The increased fT3 and suppressed TSH (with a normal fT4)
are consistent with T3 toxicosis.
 Patient: 74-year-old male

 Patient Location: General Practice

 Clinical Notes : Hypothyroid?

 TFT s
 TSH 59 mU/L (0.50–4.0)
 Free T4 <5 pmol/L (10–20)
 Patient: 74-year-old male

 Patient Location: General Practice

 Clinical Notes : Hypothyroid?

 TFT s
 TSH 59 mU/L (0.50–4.0)
 Free T4 <5 pmol/L (10–20)

 Comment
The severely increased TSH with a very low fT4
is consistent with primary hypothyroidism
 Patient: 74-year-old male (Contd.)
 One week later

 Patient Location: General Practice

 Clinical Notes : Hypothyroid, started T4 replacement 1/52 ago

 TFT s
 TSH 40 mU/L (0.50–4.0)
 Free T4 8 pmol/L (10–20)
 Patient: 74-year-old male (Contd.)
 One week later

 Patient Location: General Practice

 Clinical Notes : Hypothyroid, started T4 replacement

 TFT s
 TSH 40 mU/L (0.50–4.0)
 Free T4 8 pmol/L (10–20)

 Comment
Suggest repeat TFT measurement at least 4-6 weeks after
commencement of T4 replacement.
 Patient: 43-year-old female

 Patient Location: General Practice

 Clinical Notes on Request Form: On T4 replacement

 TFT s

 TSH 0.72 mU/L (0.50–4.0)

 Free T4 16 pmol/L (10–20)

 Patient: 43-year-old female

 Patient Location: General Practice

 Clinical Notes on Request Form: On T4 replacement

 TFT s

 TSH 0.72 mU/L (0.50–4.0)

 Free T4 16 pmol/L (10–20)

 Comment:
The normal TSH and fT4 are consistent with
adequate thyroid hormone replacement.
 Patient: 54-year-old female

 Patient Location: General Practice

 Clinical Notes on Request Form: On T4 replacement

 TFT s

 TSH 5.6 mU/L (0.50–4.0)

 Free T4 12 pmol/L (10–20)

 Patient: 54-year-old female

 Patient Location: General Practice

 Clinical Notes on Request Form: On T4 replacement

 TFT s

 TSH 5.6 mU/L (0.50–4.0)

 Free T4 12 pmol/L (10–20)

 Comment
Increased TSH suggests inadequate thyroid hormone replacement
if the dose has not been changed for at least 6 weeks and patient
has been taking the medication regularly.
Suggest review dose and repeat TFTs in in 6 weeks.
 Patient: 61-year-old male

 Patient Location: General Practice

 Clinical Notes on Request Form: On T4 replacement

 TFT s

 TSH 0.02 mU/L (0.50–4.0)

 Free T4 19 pmol/L (10–20)

 Patient: 61-year-old male

 Patient Location: General Practice

 Clinical Notes on Request Form: On T4 replacement

 TFT s

 TSH 0.02 mU/L (0.50–4.0)

 Free T4 19 pmol/L (10–20)

 Comment: Suppressed TSH is consistent with

excessive thyroid hormone replacement.
 Patient: 51-year-old female

 Patient Location: General Practice

 Clinical Notes on Request Form: Previous total thyroidectomy for

thyroid cancer. On thyroxine.

 TFT s

 TSH 0.02 mU/L (0.50–4.0)

 Free T4 19 pmol/L (10–20)

 Patient: 51-year-old female

 Patient Location: General Practice

 Clinical Notes on Request Form: Previous total thyroidectomy for

thyroid cancer. On thyroxine.

 TFT s

 TSH 0.02 mU/L (0.50–4.0)

 Free T4 19 pmol/L (10–20)

 Comment:
Previous history of thyroid Ca noted. Low TSH may be appropriate
depending on treatment targets for this patient.
 Patient: 55-year-old female
 Patient Location: General Practice

 Clinical Notes : Subclinical hypothyroidism, follow-up

 TFT s

 TSH 3.6 mU/L (0.50–4.0)

 Free T4 12 pmol/L (10–20)

 Previous Results 6 months ago:

 TSH 4.3 mU/L (0.50–4.0)
 Free T4 13 pmol/L (10–20)
 Patient: 55-year-old female
 Patient Location: General Practice

 Clinical Notes : Subclinical hypothyroidism, follow-up

 TFT s

 TSH 3.6 mU/L (0.50–4.0)

 Free T4 12 pmol/L (10–20)

 Previous Results 6 months ago:

 TSH 4.3 mU/L (0.50–4.0)
 Free T4 13 pmol/L (10–20)

 Comment
Borderline TSH persists.
Suggest repeat in one year with thyroid autoantibodies (TPO antibodies).
 Summary

 Most clinicians welcome appropriately applied interpretative

comments on Clinical Chemistry reports

 TFT report comments may improve patient outcomes

 Pathologists and Clinical Scientists have a duty to add value to reports

where appropriate, including through interpretative comments

 Go for it!
Thank you

QUESTIONS