Table 5.

Comparing methods of glomerular filtration rate estimation in different populations with a solitary kidney

Reference	n	Age of study population (yr)	Causes of a solitary kidney	Reference method of GFR measurement	eGFR	Misclassification of CKD stage
Pierrat et al. 200381	176	Children 3–19 (mean: 13.2 ± 0.36) Adults 20–75 (mean: 46 ± 1.23)	Children: 30 patients with SK and 30 patients with KT Adult: 28 patients with SK and 88 patients with KT	Corrected Cin CrClm	CrClCG Schwartz82 GFR (Sch) MDRD GFR	Children: Means of Sch and MDRD GFR overestimated mean of Cin Adult: Mean of CrClCG and of MDRD GFR were not different from Cin. In SK, mean MDRD GFR underestimated Cin CrCl overestimated Cin
Tan et al. 201083	64	21–70 (median: 49)	Living kidney donation with median time after donation of 13 months	iGFR	Urinary CrCl CrClm 4-variable MDRD estimating equation (eGFR) CKD-EPI GFR estimating equation	CrCl overestimates iGFR Both Cr-based estimating equations underestimated and were poorly correlated with iGFR Misclassification was greater in donors aged ≥ 55 yr
Ferreira-Filho et al. 201184	36	Mean: 50.7 ± 10.6	Living kidney donation 28 patients Renal stones with hydronephrosis, 8 patients Mean duration after unilateral nephrectomy: 11.6 ± 9 (2 mon to 38 yr)	CrClm	•CrCl •CrClCG •MDRD GFR	CrClCG had a better correlation with CrClm than MDRD GFR (r2 0.64 vs. 0.34, respectively). At CrClm of >90 ml/min per m2, CrClCG and MDRD GFR underestimate CrClm At CrClm <90 ml/min per m2, CrClCG and MDRD GFR overestimate CrClm
Westland et al. 201385	77	1.5–19.8	Congenital, 26 patients (34%) Acquired, 51 patients (66%)	GFR-inulin	2 Cr-based (eGFR [eGFR]-Schwartz,82 urinary CrCl); 2 cystatin C–based (eGFR-Zappitelli1,86 eGFR-CKiD 1); and 2 cystatin C/Cr–based (eGFR-Zappitelli2,86 eGFR-CKiD2)	eGFR-CKiD2 (height, sex, serum creatinine, cystatin C, and BUN) Mean bias 20.9 ml/min per 1.73 m2 95% of values within ±30% of GFR-inulin 54% of values within ±10% of GFR-inulin

BUN, blood urea nitrogen; C_in, inulin clearance; CKD, chronic kidney disease; CKD-EPI, Chronic Kidney Disease-Epidemiology Collaboration; CKiD, Chronic Kidney Disease in Children; CrCl, creatinine clearance; CrCl_CG, creatinine clearance by Cockroft-Gault equation; CrCl_m, creatinine clearance from a 24-hour urine collection; eGFR, estimated glomerular filtration rate; GFR, glomerular filtration rate; iGFR, urinary iothalamate clearance; MDRD, Modification of Diet in Renal Disease; Sch, estimated glomerular filtration rate by Schwartz (Schwartz = K × height (cm)/Pcr (mg/dl) where K = 0.55 for children aged 2 to 12 years, K = 0.55 for girls 13 to 21 years, K = 0.70 for boys 13 to 21 years, and Pcr = serum creatinine [mg/dl])⁸²; SK, single kidney; KT, kidney transplantation.