What lab work should be ordered for a patient presenting with night sweats?

Laboratory Workup for Night Sweats

For patients presenting with night sweats, initial laboratory testing should include complete blood count (CBC), thyroid-stimulating hormone (TSH), erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP), HIV testing, and tuberculosis testing (PPD or interferon-gamma release assay). 1

Initial Laboratory Evaluation

First-line Tests

• Complete blood count (CBC) with differential - To evaluate for infections, hematologic disorders, and malignancies 1
• Thyroid-stimulating hormone (TSH) - To assess for hyperthyroidism 1, 2
• Inflammatory markers - ESR or CRP to detect inflammatory conditions 1
• HIV testing - Particularly important if risk factors are present 1, 2, 3
• Tuberculosis testing - PPD skin test or interferon-gamma release assay 1, 2, 3

Additional Baseline Testing

• Comprehensive metabolic panel - To assess organ function and metabolic status 1
• Serum immunoglobulins - If immunodeficiency is suspected 4
• Coagulation parameters - If bleeding disorder is suspected 4
• Lactate dehydrogenase (LDH) - May be elevated in lymphoma and other malignancies 4

Targeted Testing Based on Clinical Suspicion

For Hematologic Malignancies

• If lymphadenopathy is present or CBC is abnormal:
  • Peripheral blood smear - To evaluate for abnormal cells 4
  • Bone marrow aspirate/biopsy - If cytopenias or abnormal peripheral blood smear are present 4

For Infectious Causes

• Chest radiography - Particularly important if respiratory symptoms are present or TB is suspected 1, 2, 3
• Blood cultures - If fever is present or endocarditis is suspected

For Autoimmune Conditions

• Autoimmune panel - Including ANA and rheumatoid factor if autoimmune disease is suspected 4

Specific Clinical Scenarios

Night Sweats with Constitutional Symptoms

If night sweats are accompanied by weight loss, fever, or lymphadenopathy:

• CT scan of chest, abdomen, and pelvis - To evaluate for lymphoma, TB, or other malignancies 3
• Consider bone marrow biopsy - Particularly if blood counts are abnormal 3

Night Sweats with Respiratory Symptoms

• Pulmonary function tests - If obstructive pattern is suspected 4
• Sputum cultures - For TB or other infections

Night Sweats with Neurological Symptoms

• Lumbar puncture - If CNS involvement is suspected 4

Interpretation and Follow-up

• If initial testing is negative but symptoms persist, consider:

  • Polysomnography - To evaluate for sleep-disordered breathing 1
  • Gastroesophageal reflux evaluation - As GERD is an often-overlooked cause of night sweats 1, 3
  • Glucose monitoring - To assess for hypoglycemia, especially in diabetic patients 1

• If all testing is negative, reassurance and continued monitoring are appropriate, as night sweats alone do not indicate an increased risk of death 2

Clinical Pearls

• Night sweats are a common symptom that may indicate serious underlying conditions but are often benign in primary care settings 2
• The most concerning causes to rule out include tuberculosis, lymphoma, and other malignancies 1, 3
• Consider medication side effects as a potential cause, including antihypertensives and serotonin reuptake inhibitors 5
• In patients with recurrent infections and night sweats, consider immunodeficiency evaluation 4

Remember that while night sweats can be associated with serious conditions, most patients presenting with this symptom in primary care do not have a life-threatening disorder 2.