Table 1.

Inclusion and exclusion criteria

Inclusion criteria (CKD)	≥18 years of age
	CKD stages 1–5
Exclusion criteria (CKD)	Current renal replacement therapy
	Active malignancy (excluding non-melanoma skin cancer)
	Immunosuppression
	Pregnancy
	Heparin administration
Inclusion criteria (HV)	≥18 years of age
	No prior known renal disease
Exclusion criteria (HV)	Exclusions as for CKD group
	Uncontrolled hypertension
	Diabetes mellitus

Exclusion criteria included: malignancy due to the known elevated levels in this group⁶; immunosuppression and pregnancy due to unknown influences of these on MK levels; heparin therapy as MK is a heparin binding molecule and is known to transiently increase MK levels.²²

CKD, chronic kidney disease; HV, healthy volunteers; MK, midkine.