Medicare (traditional, Part A/B) is randomly refusing to pay for routine blood tests. ("Not medically necessary.") In the case of billed through LabCorp (in-office testing) through primary doctor at OneMedical (acquired by Amazon). Stuck with a $150 bill as someone on SSDI without other income isn't a fun time. The "retail" price was something like $3000 for about 7 not fancy blood tests, reduced to around $350 by Medicare and then only paying $200.