A simple test, resulting in referral

Each responded to antibiotic therapy. He had an episode of pneumonia two months ago which was treated with oral antibiotics and he now presents again with pneumonia clinically and on CXR.

Sputum culture has twice grown Streptococcus pneumoniae.

FBC is normal. E/LFTs show: protein 58g/L (66–83), globulin 13 g/L (20–39).

Because of his history of recurrent infection, and also the low globulins (not always reliable), IgG, IgA and IgM are requested: IgG 3.35g/L (5.76–15.36), IgA <0.06g/L (1.24–4.16), IgM