Test combinations and profiles

Albumin
Alkaline Phosphatase (ALP)
Calcium
Phosphate (an adjusted/corrected calcium is automatically calculated and reported)

Alanine aminotransferase (ALT)
Albumin
Alkaline Phosphatase (ALP)
Total Bilirubin
Total Protein

Conjugated bilirubin is available if specifically requested but will only be done if the total bilirubin is significantly raised.

Aspartate aminotransferase and gamma-glutamyl transferase are available on specific request only.

Creatinine
Potassium
Sodium
Urea

A venous bicarbonate and/or chloride is provided on specific request only.

For bicarbonate requests - a venous blood gas sample is required.

The U&E profile also automatically includes estimated glomerular filtration rate (eGFR, using the EPI formula), plus kidney failure risk score (KFRE) and acute kidney injury (AKI) scores where appropriate (see specific boxes below for further information on these parameters)

Note: change to CKD-EPI calculation from 9 September 2019.

An eGFR result is reported on all general practitioner and hospital out patients over 18 years of age who have urea and electrolytes measured. There is no need to separately request this test – it is automatically calculated from the patient’s age, gender and serum creatinine result.

The eGFR is reported as mL/min/1.73 m2 and each result is accompanied by a brief explanatory comment and the reference for The UK Kidney Association (formerly The Renal Association) website, which can be accessed for further information about the eGFR and chronic kidney disease (CKD).

The eGFR is only an estimate and confidence intervals are quite wide. It is most likely to be inaccurate at extremes of body type for example malnourished patients or amputees.

It is not valid for use in:

• children
• pregnant women
• oedematous patients
• muscle wasting disorders
• acute renal failure
• or when the creatinine concentration is rapidly changing

There may be differences in calculated eGFR between certain ethnic groups, but evidence for these differences is poor and we no longer suggest applying a factor to allow for this

KFRE
Kidney failure risk is calculated only in patients with a CKD score between 3a and 5 and includes urinary albumin/creatinine ratio to give a likelihood of progression to end-stage renal failure within 2-5 years. This is provided in line with NICE guidance (NG203)

A calculator and furtehr information on this parameter can be found here The Kidney Failure Risk Equation

AKI status was included in the Urea and Electrolyte profile in 2016 in the response to the Government/NHS initiative to improve the care of people at risk of, or with, AKI.

An algorithm is applied through the Laboratory’s Information System to an individual’s available serum creatinine results to allow the calculation of their AKI status which is then reported and flagged in their U&E results.

Further advice on patient management is available via the hospital intranet or GP education website.

The Think Kidney website also provides further information.

Total Cholesterol
HDL Cholesterol
Non HDL Cholesterol
LDL Cholesterol (calculated)
Triglycerides (the total: HDL cholesterol ratio is automatically calculated and reported)

Requests for serum lipids should be deferred for:

• 2 weeks after minor illness
• 3 months after myocardial infarction, serious illness or pregnancy

The lab has offered high-sensitivity cardiac troponin I as its main cardiac marker since 3rd April 2019

This is to be used in line with the local ED cardiac chest pain protocol which can be found here.

Given the acute nature of tropnin measurement, and the fact that it may be necessary to repeat the test within an hour of the initial sample, the test is not recommended for use in primary care

It is a UKAS ISO 15189:2022 requirement that assays are validated for all sample types. This validation is normally performed by the instrument and assay manufacturers. It is a global issue that the manufacturers only validate the most common specimen types (serum, plasma, whole blood and urine). Fluids obtained from additional sites (such as drain, ascitic, pleuritic and joint fluids) are therefore not validated on the assays available in the Biochemistry Laboratory.

The laboratory recognises the diagnostic value of the analysis of various fluids types and therefore will continue to analyse them with a disclaimer comment indicating their non validated status. All results must be interpreted with caution.

For further information regarding interpretation please contact the Consultant Biochemists.