Non-diabetic glycosuria as a diagnostic clue for acute tubulointerstitial nephritis in patients with azotemia

Figures & data

Table 1. Clinical features and laboratory data of the study population.

	ATIN (n = 28)	Other Diagnoses (n = 116)	p-value
Age (years)	48.5 ± 14.1	53.1 ± 15.0	.144
Male/female	14/14	76/40	.128
Fever	8 (29%)	25 (22%)	.428
Rash	5 (18%)	5 (4%)	.024
White blood cells (×10^3/μL)	8.40 ± 3.17	8.28 ± 3.25	.859
Eosinophilia (>500/μL)	4 (14%)	18 (16%)	1.000
Hemoglobin (g/dL)	9.39 ± 1.85	10.91 ± 2.41	.001
Platelets (×10^3/μL)	263.7 ± 79.5	253.7 ± 92.9	.601
Creatinine (mg/dL)	3.71 (1.60–16.50)	2.15 (1.42–18.60)	<.001
eGFR (mL/min/1.73m^2)	17 (4–49)	31 (2–63)	.002
Urine microscopy
RBC (/HPF)			.072
0–2	14 (50%)	37 (32%)
≥ 3	14 (50%)	79 (68%)
WBC (/HPF)			.012
0–2	9 (32%)	68 (59%)
≥ 3	19 (68%)	48 (41%)
Pathologic diagnoses
ATIN	28	–
IgA nephropathy	–	46
ANCA–associated GN	–	34
Focal segmental glomerulosclerosis	–	7
Hypertensive nephrosclerosis	–	5
Malignant hypertension	–	3
Acute tubular necrosis	–	3
Advanced chronic GN	–	2
Thrombotic microangiopathy	–	2
Amyloidosis	–	2
Others*	–	12

Data are mean ± standard deviation, median (range) or n (%). ANCA: antineutrophil cytoplasmic antibody; ATIN: acute tubulointerstitial nephritis; eGFR: estimated glomerular filtration rate; GN: glomerulonephritis. *Others; Henoch-Schönlein purpura (1), chronic interstitial nephritis (1), lupus nephritis (1), ANCA-negative pauci-immune crescentic GN (1), polyarteritis nodosa (1), warfarin-related nephropathy (1), acute phosphate nephropathy (1), non-diagnostic (5).

Table 2. Distribution of glycosuria levels in ATIN and other diagnoses.

Urine Glucose on dipstick	ATIN (n = 28)	Other Diagnoses (n = 116)
Negative	5	99
Trace	4	10
1+	9	7
2+	6	0
3+	3	0
4+	1	0

Figure 1. Receiver operating characteristic (ROC) curve for predicting acute tubulointerstitial nephritis from urine dipstick tests for glucose. AUC: the area under the ROC curve; CI: confidence interval.

Table 3. Performance of the different cutoffs for glycosuria to predict ATIN.

Cutoff (Glycosuria)	Sensitivity (95% CI)	Specificity (95% CI)	Positive Likelihood Ratio (95% CI)	Negative Likelihood Ratio (95% CI)
Trace	82 (63–94)	85 (78–91)	5.61 (3.50–8.99)	0.21 (0.09–0.46)
1+	68 (48–84)	94 (88–98)	11.24 (5.25–24.09)	0.34 (0.20–0.59)

Table 4. Blood chemistries suggestive of tubular injury.

	ATIN (n = 28)	Other Diagnoses (n = 116)	p-value
Phosphorus (mg/dL)	3.34 ± 0.82	3.86 ± 1.08	.019
Phosphorus < 2.5 mg/dL	5 (18%)	3 (3%)	.007
Uric acid (mg/dL)	4.53 ± 2.16	7.45 ± 2.15	<.001
Uric acid < 3.0 mg/dL	5 (18%)	1 (1%)	.001
Potassium (mEq/L)	3.91 ± 0.47	4.32 ± 0.67	.003
Potassium< 3.5 mEq/L	5 (18%)	11 (9%)	.311
Total CO2 (mEq/L)	18.4 ± 4.2	21.5 ± 5.1	.003
Total CO2 < 20 mEq/L	20 (71%)	46 (40%)	.002

Data are mean ± standard deviation or n (%).