‘Fever’ implies an elevated core body temperature of more than 38.0°C). Fever is a response to cytokines and acute phase proteins and occurs in infections and in non-infectious conditions.
The differential diagnosis is very broad so clinical features are used to guide the most appropriate investigations. The systematic approach described on pages 294–295 should be followed describes the assessment of elderly patients.
If the clinical features do not suggest a specific infection,then initial investigations should include:
- A full blood count (FBC) with differential, including eosinophil count
- Urea and electrolytes, liver function tests (LFTs), blood glucose and muscle enzymes
- Inflammatory markers, erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP)
- A test for antibodies to HIV-1
- Autoantibodies, including antinuclear antibodies
- Chest X-ray and electrocardiogram (ECG)
- Urinalysis and urine culture
- Blood culture • throat swab for culture
- Other specimens, as indicated by history and examination, e.g. wound swab; sputum culture; stool culture, microscopy for ova and parasites, and Clostridium difficile toxin assay; if relevant, malaria films on 3 consecutive days or a malaria rapid diagnostic test (antigen detection,. Subsequent investigations in patients with HIVrelated ), immune-deficient), nosocomial or travel-related pyrexia and in individuals with associated symptoms or signs of involvement of the respiratory, gastrointestinal or neurological systems are described elsewhere.
Fever and its associated systemic symptoms can be treated with paracetamol, and by tepid sponging to cool the skin. Replacement of salt and water is important in patients with drenching sweats. Further management is focused on the underlying cause.