University of Wisconsin–Madison

Fecal Samples

  1. Current experimental results show that fecal water is approximately 30-75% of the mass of the fecal sample. Since we use mass as the basis for reporting hormone results, for example as ng/g (nanograms of hormone per gram of feces), there is a great possibility of error or uncertainty in the results if the fecal samples are not of the same water content or consistency. The preferred method for ensuring all samples are of the same consistency is lyophylization. Generally our lab prefers if fecal samples arrive dry and free from external particle matter like seeds, stones, grass, hay, and hair. It is more expensive and time consuming for our lab to dry (lyophylization) fecal samples or do other sample preparation work.
  2. Consider the degree of water homogeneity acceptable for your analyis–from watery to dry. It may be that the feces samples are uniform as to their moisture content so analysis can begin without the drying step. If feces samples are not homogeneous, which is the typical case, then drying is an option. Note that some steroids are water soluble and so absorbing the water with a paper towel and throwing the paper towel away may also discard your steroid. Dry feces can be obtained by lyophylization or air drying.
  3. Collect a fecal sample, we recommend gloves at all times.
    1. We only sample about 0.2 grams of feces so about 1 gram is plenty for the lab — 1 tablespoon of feces is all the lab needs but you may want to collect and store more for your own needs or subsequent analyses.
    2. Collect a fecal sample as fresh and pure as possible, no hair or grass. Extract in ethanol or freeze feces after collection and labelling. We prefer you label the samples in sequential numerals (1,2,3…n).
  4. Ship fecal samples in dry ice or other cold medium.