I believe this test is done the same way a hematocrit is done, by
spinning out a sample in a capillary tube.  Any lab can do it, they just
have not heard of it before.

You should be able to get a "quick and dirty" result just by putting a
well-mixed breast milk sample into a test tube and letting it sit and
separate.  Then just measure or estimate the amount of cream that rises
to the top - 10%, 25%, 50%, etc.

You will probably get different percentages from different samples,
depending on time of day it was expressed, whether it is from the
beginning or near the end of a feeding, what the interval was from the
last feeding, etc.

Barb Berges BS, RN, IBCLC
Rochester, New York