Case Studies

 Case 3.2 Common variable immunodeficiency

A 29-year-old woman developed herpes zoster and lobar pneumonia. Over the next 5 years, she was admitted to hospital with pneumonia on four occasions and yet there had been no history of recurrent chest infections during childhood. At the age of 33, she developed a non-erosive seronegative arthritis. On direct questioning, she gave a history of intermittent diarrhoea since her late teens. Her bowel upsets lasted from 2 days to 2 weeks and during this time she passed five to six partly formed stools a day. There was no family history of recurrent infections: she had two sons, aged 10 and 7, both of whom were well. Physical examination was normal though she was thin.

Investigations showed a haemoglobin of 115g/l with a normal white-cell count and differential. Immunological studies (Table C3.2) showed marked hypogammaglobulinaemia and no specific antibodies, despite a tetanus toxoid boost 1 year earlier. She had normal numbers of T and B lymphocytes. Antinuclear antibodies and rheumatoid factor were not detected. Investigations into the cause of her recurrent diarrhoea revealed Giardia lamblia in the jejunal aspirate.

She was diagnosed as having common variable immunodeficiency with intestinal giardiasis as a secondary complication. She was given a course of metronidazole for her Giardia infestation and fortnightly intravenous infusions of human normal IgG (400mg/kg body weight/month) for her hypogammaglobulinaemia.

Table C3.2 Immunological investigations* in Case 3.2.

*Normal adult ranges shown in brackets.