Troponin

1.1.       High Sensitive Troponin T has changed to High Senstive Troponin I

Interpretation is as follows:

99th Centile Males < 34 ng/L and Females < 16 ng/L

  • “Result is > 99th In cases of chest pain this could be indicative of an ACS.  Requires clinical assessment by cardiologist or cardiology nurse practitioner”
  • “Result indicates a detectable troponin level but below 99th  No evidence of an ACS but a second sample 1-3 hours apart is required to rule out myocardial infarction.
  • Result indicates no detectable troponin (<5 ng/L).  If the chest pain was > 6 hours ago this result makes an ACS unlikely and in the absence of high clinical suspicion no further troponin test is required.  
  • Troponin results cannot be used in isolation to diagnose or rule out an ACS.  Please use the HEART score and refer to cardiologist or cardiology nurse practitioner if advice is required.

 

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Thyroid Function Tests

TSH and free thyroxine (fT4) are provided as first-line tests. Since many drugs and treatments affect thyroid function tests, details of all drugs or other treatment must be provided in order that further tests can be initiated by the laboratory as appropriate. Please indicate on request form if patient is on thyroid hormone replacement.

Free T3 is analysed only according to an agreed protocol and full clinical details must be given on the request form.

Thyroid hormone measurements can be misleading in patients with acute and non-thyroid illness. Thyroid status should only be assessed after recovery from acute non-thyroidal illness. 'Screening' of patients in hospital for thyroid illness is not recommended.

Please see the UK Guidelines for the Use of Thyroid Function Tests at: http://www.british-thyroid-association.org/current-bta-guidelines-

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Management of the Menopause

The menopausal transition is best diagnosed on clinical grounds. Endocrine investigation may be helpful where the pattern of age, menstrual history and features of oestrogen deficiency are unusual.

Please indicate the woman’s date of birth, recent menstrual pattern and date of last menstrual period/day of cycle on which the blood sample was collected. A rise in follicle stimulating hormone (FSH) is the earliest sign of the approaching menopause. Measurement of serum FSH is the recommended first investigation if biochemical confirmation is necessary. The measurement of luteinising hormone (LH), oestradiol or progesterone is not appropriate. A serum FSH in the reference range for the follicular phase does not exclude the perimenopause.

Hormone Replacement Therapy

HRT when prescribed (orally or transdermally) for the relief of menopausal symptoms does not require endocrine monitoring. Where there is unexpected failure of treatment, for example due to non-compliance or malabsorption, investigation may be useful. Different formulations of HRT may or may not be detected by oestradiol assays. Please indicate on the request form the HRT preparation prescribed.

The main indication for measuring oestradiol in women on HRT is in those receiving implants containing oestradiol. Early replacement of the implant may result in accumulation of oestradiol. Monitoring of serum oestradiol before the implant is replaced has been recommended to avoid supraphysiological concentrations. Sometimes testosterone implants are used in HRT. Measurement of testosterone in an analogous fashion to oestradiol may help to assess whether a further implant may be necessary.

 

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Coronary Heart Disease Risk Score

Standard 4 of the National Service Framework for Coronary Heart Disease states that:

“General Practitioners and Primary Health Care teams should identify all people at significant risk of cardiovascular disease (CVD) but who have not yet developed symptoms and offer them appropriate advice and treatment to reduce their risk”.

Numerous risk calculators are available to calculate risk for coronary disease and these are all based on the Framingham model. The JBS III or the QRISK 2016 calculators are used for the calculation of cardiovascular disease risk. The South Birmingham PCT requires general practice to screen for CVD and any request for ‘CVD risk’ will generate a total cholesterol, HDL-cholesterol, creatinine and HbA1c (a yellow top and purple top bottle must be supplied). There are freely available calculators available to calculate a ‘CHD risk’ (Coronary heart disease risk) score (e.g. http://www.qintervention.org/)

Please note HDL-cholesterol is only measured when the CHD risk score is requested. We do not provide HDL-cholesterol otherwise on any request for a lipid profile.

Often we are asked to provide LDL-cholesterol calculations. For your convenience the calculation of LDL-cholesterol is provided below but you should recognise that this is only strictly valid where patients attend fasting for at least 12 hours in order to suppress triglyceride concentrations. Triglyceride concentrations >4.5 mmol/L negate the use of the calculation;

LDL cholesterol = Total cholesterol – HDL-cholesterol – (Triglyceride/2.19)

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