Urinary Macrophage Migration Inhibitory Factor Serves as a Potential Biomarker for Acute Kidney Injury in Patients with Acute Pyelonephritis

Table 1

Demographic data and clinical characteristics of patients with APN.

Clinical variables	Number of cases (%)
	Without AKI; (𝑛=26)	With AKI; (𝑛=13)	P value
Age (yrs)	66 ± 18	73 ± 10	0.204
Male	9 (35)	4 (31)	1.000
Comorbidity
Diabetes mellitus	13 (50)	6 (46)	1.000
Hypertension	15 (58)	9 (69)	0.728
CKD (eGFR < 60 mL/min/1.73 m^2)	7 (27)	6 (46)	0.290
Baseline eGFR^a	79 ± 33	67 ± 46	0.322
Laboratory data
White blood cell count (k/μL)	12.7 ± 4.8	13.9 ± 8.4	0.565
Absolute neutrophil count (k/μL)	10.8 ± 4.8	11.1 ± 7.5	0.858
C-reactive protein (mg/dL)	99 ± 107	115 ± 67	0.669
Creatinine (mg/dL)	1.4 ± 1.3	3.4 ± 2.0	0.003
Blood urea nitrogen (mg/dL)	28.9 ± 29.6	68.7 ± 36.2	0.001
Current eGFR^b	78 ± 40	22 ± 15	<0.001
Urine MIF (ng/mg)^c	4.2 ± 3.5	17.0 ± 13.2	0.004
Serum MIF (ng/mL)	259.6 ± 240.9	279.8 ± 248.1	0.810
Gram-negative bacteria^d	24 (92)	12 (92)	1.000
Severity score
REMS	7.5 ± 3.6	7.7 ± 2.8	0.893
RAPS	2.1 ± 2.0	3.2 ± 2.3	0.174

Categorical variables are expressed as a number (percentage), and continuous variables are expressed as the mean ± SD. AKI: acute kidney injury; CKD: chronic kidney disease; eGFR: estimated glomerular filtration rate; MIF: macrophage migration inhibitory factor; REMS: rapid emergency medicine score; RAPS: rapid acute physiology score.
^aThe baseline eGFR was estimated using the MDRD equation, and the units are mL/min/1.73 m².
^bThe current eGFR was estimated by the MDRD equation using the serum creatinine level while the patient arrived at the emergency department.
^cThe concentrations of MIF in the urine were measured by ELISA and were normalized based on the urinary creatinine levels. We divided the urine levels of MIF by urine creatinine to measure the adjusted urine MIF (ng/mg).
^dThe bacterial pathogens of APN were identified and proven as Gram-negative bacteria.