In the head-to-head comparison of HF-HD versus MCO-HD, the RR of middle moleculessuch as ß2-microglobulin (12 kDa), cystatin C (13 kDa), myoglobin (17 kDa),prolactin (23 kDa), kappa FLC (23 kDa), complement factor D (24 kDa), α1-acidglycoprotein (41 kDa), lambda FLC (45 kDa) was robustly higher in MCO-HD17,31,36,37. Here, MB is linked to hydrops fetalis.