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Clin Chem Lab Med. 2014 Aug;52(8):1203-9. doi: 10.1515/cclm-2013-1074.

A new sampling device for faecal immunochemical testing: haemoglobin stability is still an open issue.



The detection of faecal occult blood is a fundamental step in making an early diagnosis of colorectal cancer. The aim of the present study was to evaluate the stability of haemoglobin in faeces collected with two sampling devices specific for faecal immunochemical testing (FOB Gold Tube Screen and FOB Gold Tube NG) that contain different preservative buffers (buffer H, BH, and buffer N, BN, respectively).


Fifteen true positive faecal samples were collected with both devices. A pool from each sample was made. Each pool was portioned and stored at +4°C, +21°C and +32°C for 10 days. One aliquot of each pool stored at each of the respective temperatures was tested at five time intervals between sampling and analysis. The same procedure was followed for three synthetic haemoglobin solutions in both buffers.


The percentage of cumulative faecal haemoglobin decrease (HbCD%) was evaluated. No significant difference was found between BH and BN in HbCD% at +4°C (p=0.106); at +21°C and +32°C, HbCD% was lower in BH than in BN samples (p=0.002 and p=0.001, respectively) whereas no difference was found between samples stored in BH at +4°C and +21°C. The synthetic haemoglobin degradation percentage was always ≤ 7.1% for both buffers except for BN at +32°C (about 60%).


Synthetic haemoglobin solutions behave differently from the true faecal samples. At +21°C and +32°C BH preserves the haemoglobin better than BN, independent of the haemoglobin concentration. BH, allowing sample stability at both +4°C and +21°C, is more suitable for screening procedures.

[Indexed for MEDLINE]

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