Note 8 - Revenue - Revenue by Major Source (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenues	$ 6,087	$ 3,314	$ 11,800	$ 10,851
Testing [Member]
Revenues	5,367	2,941	10,416	9,774
Shipping/Collection (Hair) [Member]
Revenues	680	353	1,295	1,013
Other Revenue [Member]
Revenues	$ 40	$ 20	$ 89	$ 64