IgG4-Related Tubulointerstitial Nephritis Associated with Membranous Nephropathy in Two Patients: Remission after Administering a Combination of Steroid and Mizoribine

Table 1

Laboratory findings.

	Case 1	Case 2
Urinalysis; protein/blood	3+/3+	2+/2+
Urinary protein (g/day)	1.4	2.73
Urinary 𝛽2MG (μg/L)	11,080	858 (ref, 0–230)
Urinary NAG (U/L)	31.9	151.2 (ref, 0–11.5)
Creatinine (mg/dL)	1.0	0.9
CCr (mL/min)	92.4	49.1
BUN (mg/dL)	15.4	16.1
WBC (Eosinophil) (×10^9/L) (%)	11.5 (47.5)	7.4 (46.5)
Hemoglobin (g/dL)	11.9	9.5
Hematocrit (%)	35.4	28.5
Total protein (g/dL)	9.3	7.6
Albumin (g/dL)	2.2	1.7
AST (U/L)	27	43
ALT (U/L)	15	33
ALP (U/L)	492	480
Bilirubin, total (mg/dL)	0.4	0.4
Amylase (U/L)	60	N/A
CRP (mg/dL)	1.7	0.4
CH50 (U/mL)	<5	<5 (ref, 25–48)
C3 (mg/dL)	39	21 (ref, 86–160)
C4 (mg/dL)	2.0	<2 (ref, 17–45)
Antinuclear antibody	1 : 320 (Homo/Spec)	<1 : 40
Anti-dsDNA antibody	Negative	Negative
Anti-Sm antibody	Negative	Negative
Anti-RNP antibody	Negative	16.0
Anti-SSA antibody	Negative	Negative
Anti-SSB antibody	Negative	N/A
ANCA	Negative	Negative
IgA (mg/dL)	183	386 (ref, 110–410)
IgM (mg/dL)	37	468 (ref, 83–190)
IgE (mg/dL)	413	1811 (ref, 0–202)
IgG (mg/dL)	6989	6350 (ref, 870–1700)
IgG1 (mg/dL)	1710	2460 (ref, 423–1080)
IgG2 (mg/dL)	2280	1740 (ref, 265–931)
IgG3 (mg/dL)	249	1100 (ref, 5–121)
IgG4 (mg/dL)	2750	1050 (ref, 4–108)
S-IL2 receptor (U/mL)	3912	3973 (ref, 190–650)
SPEP	Normal	Normal
Cryoglobulin	Negative	Negative

Note: Conversion factors for units: Creatinine in mg/dL to μmol/L, ×88.4; CCr in mL/min to mL/s, ×0.01667; BUN in mg/dL to mmol/L, ×0.357; Hemoglobin, Total protein, and Albumin in g/dL to g/L, ×10; Bilirubin in mg/dL to mol/L, ×17.1; CRP in mg/dL to mg/L, ×10; IgA, IgM, IgE in mg/dL to mg/L, ×10; IgG, IgG1, IgG2, IgG3, and IgG4 in mg/dL to g/L, ×0.01. No conversion necessary for C3, C4 in mg/dL and g/L.
Abbreviations and definitions: 𝛽2MG, 𝛽2 microglobulin; NAG, N-acetyl-beta-D-glucosaminidase; CCr, creatinine clearance; WBC, white blood cell; AST, aspartate aminotransferase; ALT, alanine aminotransferase; ALP, alkaline phosphatase; CRP, C-reactive protein; ANCA, antineutrophil cytoplasmic antibody; IgA, immunoglobulin A; S-IL2 receptor, soluble interleukin-2 receptor; SPEP, serum protein electrophoresis; ref, reference range.