fevers, Pyrexia, Hyperthermia & Night Sweats

Definitions

• Fever: temperature > 38 degrees

• Pyrexia is the same as a fever, clinical term

• Night sweats: drenching sweating overnight requiring clothes to be changed

• Hyperthermia: inappropriate raise in body temperature without requirement for inflammatory response

Fevers

Exam Cram

• Fevers are caused by the hypothalamus raising the internal body temperature in order to raise the metabolic rate

• Fevers are most commonly a physiological response to infection but persistent fevers suggest chronic immune activation by chronic infection, inflammation or malignancy

• Diagnosis: temperature > 38 degrees

• Management: if well- fluids, rest +- paracetamol/ ibuprofen can be appropriate

Aetiology

Infection

An isolate acute fever in a well patient is presumed to be a viral infection and should self terminate. 

• Viral infections- most common cause

• Bacterial infection- more unwell with focal symptoms

• Tuberculosis- chronic fevers + exposure risk

Malignancy

• All systemic malignancies can cause persistent fevColitisers, though more common in haematological cancers

• Lymphoma typically causes B - symptoms: night sweats, weight loss and fevers

• Malignant fevers are treated by treating the cancer, but often present after treatments have failed

Inflammatory Disorders

• Acute exacerbation of systemic autoimmune condition: SLE, RA, IBD, Sarcoidosis, Amyloidosis 

• Immune reaction to blood, allergy or anaphylaxis, 

• Significant inflammation: Pancreatitis, Colitis, Pericarditis, Myocarditis,

• Famously: Familial Mediterranean fever (FMF) is a genetic autoinflammatory condition

Wider

• Vascular: Stroke, Pulmonary Embolus, 

• Endocrine: Hyperthyroidism- thyrotoxic storm

Hyperthermia (inappropriately activated immune system)

• Drug

  • Serotonin Syndrome - hyper reflexia, clonus

  • Neuroleptic Malignant Syndrome- lead pipe rigidity

  • Recreational stimulants: cocaine, amphetamines

• Heatstroke

Diagnosis

Diagnostic Criteria: temperature > 38 degrees

Investigation Escalation:

1. History/ examination/ observations

2. Septic screen: urine dip + culture, blood cultures x3, viral PCR, chest XR +- focal infection- i.e. skin swab

3. CT Chest Abdo Pelvis ?deep collection ?malignancy, 

   1. Consider malignancy biomarkers e.g. PSA, Ca 19-9, Ca 125, CEA, AFP & scopes

4. PET FDG CT Scan

5. White Cell Scan

Pyrexia unknown origin: temperature > 38.3 lasting for greater than 3 weeks without a focal cause

Management

1. Symptom: paracetamol, iburpofen, rest, fluids

2. Treat underlying cause

Paracetamol is commonly given for a fever, which can be reasonable if provides symptomatic relief. There is no evidence bringing down a fever causes harm or provides a benefit. Personally, I feel it is a physiologic response which is best left unless it is very high or causing distress. 

Hyperthermia

Anecdotally, everyone appears to answer yes to the question of night sweats. Drenching night sweats with changing PJ overnight is a concerning B symptom for lymphoma or myeloma. 

Night Sweats

Anecdotally, everyone appears to answer yes to the question of night sweats. Drenching night sweats with changing PJ overnight is a concerning B symptom for lymphoma or myeloma.