Throwing stones: kidney stone incidence in living kidney donor candidates with increased metabolic risk

Figures & data

Figure 1. Flow chart of selection of the patients.

Table 1. Cohort characteristics.

	Total (n = 69)	No donation (N = 39)	Donation (N = 30)	p Value
Age at time of donation/refusal (years), median (IQR)	43 (37–53)	48 (34–58)	42 (37–48)	0.21
Gender (male), n (%)	31 (45%)	20 (51%)	11 (37%)	0.33
Race/ethnicity, n (%)				0.68
White	67 (97%)	38 (97%)	29 (97%)
Black	1 (1%)	1 (3%)	0 (0%)
Native American/Alaskan native	1 (1%)	0 (0%)	1 (3%)
BMI (kg/m^2), median (IQR)	26.5 (23.3–28.9)	26.2 (23.1–29.3)	26.8 (23.7–28.5)	0.75
Alcohol use, n (%)				0.54
Never	37 (54%)	20 (53%)	17 (57%)
Occasional	30 (44%)	18 (47%)	12 (40%)
Regular	1 (1%)	0 (0%)	1 (3%)
Family history of kidney stones, n (%)	25 (36%)	17 (44%)	8 (27%)	0.21
Kidney stones diagnosed prior to donor workup, n (%)	21 (30%)	16 (41%)	5 (17%)	0.037
Kidney stone risk identified at donor workup, n (%)
Past history of kidney stones	21 (30%)	16 (41%)	5 (17%)	0.037
Incidental stone on CT	20 (29%)	11 (28%)	9 (30%)	1.00
Abnormal urine metabolic test	54 (78%)	32 (82%)	22 (73%)	0.40
Combination of stone risk, n (%)				0.081
Prior history of stones only	8 (12%)	4 (10%)	4 (13%)
Incidental stone on CT only	5 (7%)	1 (3%)	4 (13%)
Abnormal urine metabolic test only	31 (45%)	15 (38%)	16 (53%)
Prior history of stones and incidental stone on CT	2 (3%)	2 (5%)	0 (0%)
Prior history of stones and abnormal urine metabolic test	10 (14%)	9 (23%)	1 (3%)
Incidental stone on CT and abnormal urine metabolic test	12 (17%)	7 (18%)	5 (17%)
All three stone risks	1 (1%)	1 (3%)	0 (0%)
The number of kidney stone risk, n (%)				0.012^a
1	44 (64%)	20 (51%)	24 (80%)
2	24 (35%)	18 (46%)	6 (20%)
3	1 (1%)	1 (3%)	0 (0%)
Abnormal urine supersaturation, n (%)
Calcium oxalate (>5)	21 (30%)	16 (41%)	5 (17%)	0.037
Calcium hydrogen phosphate (>2)	18 (26%)	12 (31%)	6 (20%)	0.41
Uric acid (>1)	11 (16%)	8 (21%)	3 (10%)	0.33
Abnormal urine analytes, n (%)
Calcium (>250 mg/24h)	20 (29%)	13 (33%)	7 (23%)	0.43
Oxalate (female, >40 mg/24h; male, >49 mg/24h)	8 (12%)	1 (3%)	7 (23%)	0.018
Uric acid (>750 mg/24h)	12 (17%)	7 (18%)	5 (17%)	1.00
Citric acid (<320 mg/24h)	14 (20%)	8 (21%)	6 (20%)	1.00
New kidney stone events after donation/refusal, n (%)	0 (0%)	0 (0%)	0 (0%)	N/A^b

The Mann-Whitney test was used for continuous variables, and Fisher’s exact test for categorical variables.

^aTrend analysis was performed using the Cochran–Armitage test.

^bN/A: not applicable.