Table 1. Laboratory data of 48-year-old patient with index finger cyanosis

White blood cell count (× 10⁹/L)

3.5–9.5

9

Normal

Hemoglobin (g/L)

12–17.5

14.8

Normal

Mean corpuscular volume (fL)

82–92

87

Normal

Platelet count (mL)

150–450

329

Normal

Blood urea nitrogen (mg/dL)

7–20

10

Normal

Creatinine (mg/dL)

0.6–1.2

0.9

Normal

Aspartate aminotransferase (U/L)

15–40

18

Normal

Alanine aminotransferase (U/L)

9–50

19

Normal

24-h urine protein (mg/day)

< 80

126

Normal

Erythrocyte sedimentation rate (mm/h)

< 22

47

Elevated

C-reactive protein (mg/L)

0–8

67 (3+)

Elevated

Rheumatoid factor (IU/mL)

< 20

175 (3+)

Elevated

Anti-citrullinated protein antibody (IU/mL)

< 20

3.5

Negative

Antinuclear antibodies

1:100

Negative

Double-stranded DNA antibody (IU/mL)

–

Negative

Complement component 3 (mg/dL)

90–150

127

Normal

Complement component 4 (mg/dL)

10–40

17

Normal

Cytoplasmic antineutrophil cytoplasmic antibodies (AU/mL)

<15

113

Elevated

Perinuclear antineutrophil cytoplasmic antibodies (AU/mL)

< 15

< 3

Normal

Lupus anticoagulant

–

Negative

Anticardiolipin antibody IgG

< 30

65.2

Elevated

Anticardiolipin antibody IgM

< 30

22.6

Negative

Beta-2-glycoprotein I IgG (U/m)

< 40

4.8

Negative

Beta-2-glycoprotein I IgM (U/m)

< 40

< 3

Negative

Hepatitis B surface antigen (mIU)

–

Negative

Hepatitis C virus antibody (mIU)

–

Negative

Human immunodeficiency virus antibody (mIU)

–

Negative

SARS-CoV-2 PCR

–

Negative