Laboratory studies that were done were
- complete blood count with differential,
- complete metabolic panel,
- international normalized ratio,
- D-dimer,
- lipid panel,
- 25-hydroxyvitamin D,
- thyroid-stimulating hormone,
- free thyroxine,
- hemoglobin A1c (HbA1c),
- high-sensitivity CRP (hsCRP),
- cystatin C,
- N-terminal pro–B-type natriuretic peptide,
- troponin,
- urinalysis, and
- urinary albumin–creatinine ratio (uACR).
These tests were selected on the basis of their routine availability and standardized use across CLIA-certified laboratories, prior literature, and clinical expertise of the RECOVER investigators.
Other studies
The IncellDX / Patterson group has published various papers on IncellDX’s cytokine testing. To me it’s a flop, but they claim otherwise. The cytokine testing approach hasn’t worked in the past for ME/CFS.
German researchers associated with PostVac Germany tested GPCR autoantibodies and some other common tests. That had mixed results.
Source
NBC news article: Why there's no test yet for long Covid
Actual paper: https://www.acpjournals.org/doi/10.7326/M24-0737