Selective Subnormal IgG1 in 54 Adult Index Patients with Frequent or Severe Bacterial Respiratory Tract Infections

Table 1

Serum immunoglobulins in 54 adults with selective subnormal IgG1.

Ig isotype	Men ()	Women ()	Value of
Median IgG, g/L	6.71 (5.51, 8.84)	7.13 (3.86, 11.14)	0.2212
Elevated IgG, % ()	0	0	~1
Median IgG1, g/L	3.37 (2.93, 4.10)	3.78 (0.95, 4.19)	0.2794
Elevated IgG1, % ()	0	0	~1
Median IgG2, g/L	2.41 (1.61, 4.01)	2.28 (1.25, 7.24)	0.7968
Elevated IgG2, % ()	0	0	~1
Median IgG3, g/L	0.50 (0.43, 1.76)	0.59 (0.41, 1.18)	0.3342
Elevated IgG3, % ()	14.3 ()	0	0.1296
Median IgG4, g/L	0.12 (0.01, 0.46)	0.09 (0.02, 0.64)	0.6993
Elevated IgG4, % ()	14.3 ()	0	0.1296
Median IgA, mg/L	181 (90, 256)	154 (80, 489)	0.8368
Elevated IgA, % ()	0	2.1 ()	0.8704
Median IgM, mg/L	147 (44, 408)	100 (40, 277)	0.6246
Elevated IgM, % ()	14.3 ()	8.5 ()	0.5150

By definition, all patients had subnormal IgG1 and no patient had subnormal IgG2, IgG3, IgG4, IgA, or IgM.
Reference ranges are as follows: IgG 7.0–16.0 g/L (700–1600 mg/dL); IgG1 4.2–12.9 g/L (422–1292 mg/dL); IgG2 1.2–7.5 g/L (117–747 mg/dL); IgG3 0.4–1.3 g/L (41–129 mg/dL); IgG4 0–2.9 g/L (1–291 mg/dL); IgA 700–4000 mg/L (70–400 mg/dL); and IgM 400–2300 mg/L (40–230 mg/dL). Subnormal Ig levels were defined as those below the corresponding lower reference limit. Serum Ig levels are expressed as median (range). Elevated serum Ig levels were defined as those greater than the upper reference limit. Comparisons were made with Mann-Whitney test, Pearson’s test, or Fisher’s exact test, as appropriate.