Background: Published data imply that adult concentrations are achieved
for all Ig isotypes and plateau by 15--18 years of age. Recent data, however, suggest
that these results are not applicable in the elderly. There are no equivalent data
for IgG subclasses. We present reference range data for an elderly UK patient
population, for IgG, IgA, IgM and IgG subclasses.
Methods: Serum immunoglobulins were reviewed on samples from 1146
patients > 60 years of age and 925 patients aged 18--60 years. Serum IgG
subclasses were reviewed on samples from 498 patients >60 years and 484 patients
aged 18--60 years. All Igs and subclasses were measured by nephelometry. Reference
ranges were derived by probability plotting.
Results: Serum median IgG and IgM concentrations are reduced in the
elderly (IgG female P < 0·001, IgG male P <
0·03; IgM female P < 0·001, IgM male P <
0·001). Serum IgA concentrations are maintained. Indeed, men showed a slight increase
in serum IgA with age (P = 0·03). Few differences dependent on
gender were seen. Median IgM was lower in men in the younger age groups (18--60 years
P < 0·001; 61--70 years P = 0·017). IgG2
is reduced in elderly men (P = 0·002) and IgG, reduced in elderly
women (P = 0·009).
Conclusions: We advocate that centres offering these investigations
provide local, method-dependent reference ranges, and suggest an approach as to how
this might be achieved.
