1 Thyroid Testing Strategies in the South-West and Wessex A survey conducted on behalf of the ACB SW&W Regional Committee by Roberta Goodall

2 Survey Structure and Responses Questionnaire ed to audit leads 24 laboratories surveyed – 13 South West, 11 Wessex – 2 known 'pairs' (ie shared protocol/testing) – 1 assumed pair – 21 expected responses 20 questionnaires returned

3 TestSW labs Wessex labsTotal TSH only TSH + fT TSH + fT Q1. What is (are) your frontline test(s) for thyroid function?

4 Q2. What are your reference ranges? Nearly all different – even with same instrument Ranges below show lowest quoted lower limits with highest upper limits TSH mU/L fT4 pmol/L fT3 pmol/L 0.03 – – 26 to 7.8* Smallest0.27 – – – 6.8 ( ) Largest0.3 – – – 7.8 * One lab goes as high as 8.8 on an age related range (<40yrs)

5 Q3. Do you perform reflex testing? 'No' TSH+fT4 3/5 'Yes' TSH only 14/14 TSH+fT4 2/5 TSH+fT3 1/1

6 Q3. What is/are the rule(s) and the reflex analyte(s)? Based on front–line result TSH TSH/fT4 TSH/fT3 TSH low – add fT4 9 TSH low – add fT3 51 TSH high – add fT4 10 fT4 high – add fT31 Low TSH, on T4 – add fT4 2 Persistent elevated TSH – add TPO 1

7 Q3. What is/are the rule(s) and the reflex analyte(s)? Frontline can change based on certain criteria, for example Paediatric patients always get both – 7/20 respondents Certain consultants get fT4 frontline (or whatever they ask for) – 1(2)/20 Clinical information will change request – 2 nd line rather than reflex? – too many to list but e.g Differentiation made between diagnostic testing (TSH only) and known disease fT4 added to both treated hypos and hypers fT4 (and fT3) added to hypopit Concomitant therapy eg amiodarone, Li, get fT4 (and fT3) regardless All rules / protocols can change at the discretion of the signer at clinical validation.

8 Q3. How is it / are they activated? 17 / 20 perform (rule based?) reflex testing Automatically by computer/analyser 4 At technical validation by BMS1 At clinical authorisation3 Basic rule auto / extras at validation8 Basic rule at TA / extras at validation1

9 Q3. What proportion cascade to a second line test? 0 – 10%7 (4 were < 5%) 11 – 20%5 21 – 30%2 31 – 40%1 41 – 50%0 51 – 60 %1

10 Q4. Do you have criteria for requesting / analysing thyroid antibodies and, if so, what are they and which antibodies do you perform / request? No criteria (or other explanation) 3 Done elsewhere (no other information given)1 TPO antibody 11 Anti-T41 TSH receptor antibodies1 Type not stated (assume TPO)3

11 Criteria for TPO (14/16) (recommended, suggested, requested) TSH TSH/fT4 TSH/fT3 Borderline / slight  TSH (usually on rpt)  TSH (persistent/gross, discretion of signer) 1 Not defined (discretion of signer)2 Rarely / not suggested1 Suspicious/mismatched results1 Sub-clinical / compensated hypo 2 1 Q4. Do you have criteria for requesting / analysing thyroid antibodies and, if so, what are they and which antibodies do you perform / request?

12 Q5. What analytical platform do you use for your thyroid function tests? TSH TSH/fT4 TSH/fT3 Roche Elecsys 1 1 Bayer Centaur 4 3 DPC Immulite 3 1 Roche Modular 3 Beckman Access + IMX 1 Abbott AxSym 1 Immuno 1 2

13 Q6. What is your annual TFT workload? Number of TFT requests (1000s pa) TSH TSH/fT4 TSH/fT3 20 – – – – – – – – – 110 1

14 Q7. - any comments? ' ….remain unconvinced of the need to go over to dual frontline. This would cost an additional £60K/year, plus the need for another analyser. fT4 is also more of a problem assay and if always done could lead to more patients being investigated for possible hypopit at considerable extra cost.' ' ? dual front-line vs TSH only must be a quality, not a cost issue' ' we have always performed fT4 and TSH frontline. We pick up approx 6-8 hypopit pts/year (38,000 requests pa) that would otherwise be missed using TSH alone'

15 'Not averse to frontline TSH. Would however miss some hypopit. + miss other relevant findings eg if anti-thyroid drug therapy not recorded 'We wish to introduce frontline fT4 plus TSH (in line with current guidelines) but have not had success getting funding although we are supported by our endocrinologist. 'The reasons for not having dual front line TSH and fT4 on all samples are largely economic.' Q7. - any comments?