Note 2 - Summary of Significant Accounting Policies - Revenue by Major Source (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Revenues	$ 25,240	$ 24,909	$ 21,360
Testing [Member]
Revenues	21,608	21,894	19,068
Shipping/Collection (Hair) [Member]
Revenues	3,476	2,847	2,174
Other Revenue [Member]
Revenues	$ 156	$ 168	$ 118