Table 2.

Characteristics of the included studies comparing serum klotho between KTx recipients and healthy volunteers.

Study	Year	Country	N-KTx	Characteristics-KTx	Klotho-KTx (pg/mL)	Other Markers-KTx	N-Control	Klotho-Control (pg/mL)	Other Markers-Control
Balogu et al.		Turkey	40	N/A	153 ± 170	FGF23	20 healthy subjects	641 ± 1797	FGF23
						47.4 ± 61 pg/mL			1.6 ± 1.3 pg/mL
Malyszko et al.	2014	Poland	84	Median time from KTx	228 (161–384)	eGFR	22 healthy subjects	757 (632–839)	eGFR
						56.3 ± 1.6
				37 (13–72) months		ml/min/1.73 m2			97.3 ± 13.5 mL/min/1.73 m2
				Age 47.9 ± 12.0 years		FGF23			FGF23
				Male 64 (76%)		16.7 (13.8–21.2) pg/mL			11.7 (10.8–17.2) pg/mL
Bleskestad et al.	2015	Norway	40	Median time from KTx	605 (506–784)	eGFR	39 GFR-matched controls	GFR-matched controls	GFR-matched control
									eGFR
									62 (57–73) mL/min/1.73 m2
									iFGF23
									63 (52–87) pg/mL
									Healthy volunteer
									eGFR
									99.5 (89.5–110.8)
				18.3 (IQR 12.2–26.2) years		62 (52–72) mL/min/1.73 m2		660 (536–847)	mL/min/1.73 m2
				Age 61.3 ± 11.8 years		iFGF23	20 healthy subjects	Healthy volunteers	iFGF23
				Male 29 (73%)		75 (53–108) pg/mL		692 (618–866)	51 (36–68) pg/mL
Tartaglione et al.	2017	Italy	80	Time for KTx	449 (388–534)	eGFR	30 healthy subjects	795 (619–901)	eGFR
				77.6 (37.6–119.5) months		46.3 (36.2–58.3) mL/min/1.73 m2			109.1 ± 14.1 mL/min/1.73 m2
				Age 54.7 ± 10.3 years		FGF23			FGF23
				Male 49 (61%)		41 (25–59) pg/mL			34 (28–441) pg/mL
Nahandi et al.	2017	Iran	30	Time from KTx	276 ± 241	eGFR	27 healthy subjects	N/A	N/A
				6.42 ± 2.44 years		64.53 ± 17.83 mL/min/1.73 m2
				Age 30.9 ± 5.3 years

Abbreviations: eGFR, estimated glomerular filtration rate; FGF23, fibroblast growth factor-23; KTx, kidney transplant; N/A, not available.