** REVISED** Sample acceptance/rejection criteria

A porphyrin request form must accompany all samples sent to the laboratory. Forms can be obtained by contacting the laboratory directly or via the request form section. We do not accept verbal requests for examinations.

The table below summarises the minimal essential information required on samples and request forms to enable their acceptance by the laboratory. Samples or request forms that are received without the minimum essential criteria will be rejected without analysis except in cases where a repeat sample would not be easily accessible. In these cases, the samples may be processed at the discretion of a senior member of staff and the shortcoming of the sample or request documented on the report form. Samples will not be accepted without a request form.

†Samples without a collection date will be accepted for analysis but classified as deviating. As porphyrins are unstable and degrade over time any negative results should be interpreted with caution and additional samples sent if clinical suspicion of porphyria remains.

In addition to the minimum acceptance/rejection criteria stated above, the sample specifications that are required for sample acceptance by SCPS are outlined below. Any sample that does not meet or is suspected not to meet these will be considered to be a deviating sample:

1. Samples must be in acceptable containers (see sample requirements)
2. Samples must be protected from light. Porphyrins are sensitive to light and therefore all samples sent for porphyrin testing must be protected from light. Samples that have been exposed to light will still be analysed, but repeat samples requested to rule out false negatives depending on the nature/duration of light exposure
3. **NEW** Urine and faecal specimens should not be subjected to ambient temperature for more than 24 hours following collection – samples exceeding 24 hours will still be analysed, but repeat samples may be requested to rule out false negatives
4. **NEW** Whole blood specimens should not be subjected to ambient temperature for more than 7 days following collection – samples exceeding 7 days will still be analysed, but repeat samples may be requested to rule out false negatives
5. Sample containers must be intact and not leaked significantly in transit
6. Samples must be of sufficient volume for analysis (see sample requirements)
7. Liquid stool samples are not suitable for analysis
8. Samples must be of sufficient quality for analysis – dilute urine samples (<2 mmol/l creatinine) are unsuitable for analysis; haemolysed/lipaemic blood samples may be analysed but the results should be interpreted with caution

Any sample that does not meet, or is suspected not to meet, the SCPS requirements will be classed as a deviating sample. If the sample can be processed, the referrer will not normally be alerted to the deviation until reporting, where a disclaimer will be included in the report.

Source: PBUL009 01/08/2024 Issue:3 Review:0