From the Guidelines
For chronic fatigue and diffuse pain, the most essential laboratory tests to order are a complete blood count (CBC), comprehensive metabolic panel, thyroid function tests (TSH, free T4), inflammatory markers (ESR, CRP), and urinalysis for protein, blood, and glucose, as recommended by the European Organisation for Research and Treatment of Cancer (EORTC) guidelines 1. These tests help identify common underlying causes such as anemia, thyroid disorders, vitamin deficiencies, inflammatory conditions, autoimmune diseases, and infections that can manifest as fatigue and widespread pain. Key laboratory tests to consider include:
- Complete blood count (CBC) to rule out anemia or infection
- Comprehensive metabolic panel to assess electrolyte and metabolic status
- Thyroid function tests (TSH, free T4) to evaluate thyroid function
- Inflammatory markers (ESR, CRP) to assess for underlying inflammation
- Urinalysis for protein, blood, and glucose to evaluate renal function and rule out underlying infections
- Vitamin levels (B12, D, folate) and iron studies (ferritin, iron, TIBC) may also be considered to rule out deficiencies It's essential to combine laboratory testing with a thorough clinical history and physical examination, as chronic fatigue syndrome and fibromyalgia remain diagnoses of exclusion after ruling out other medical conditions 1. A diagnostic assessment should include a focused fatigue history, a thorough medical examination, an evaluation of the status of the underlying condition, a review of body systems, a mental status examination, and laboratory blood tests, as outlined in the ESMO clinical practice guidelines for diagnosis and treatment of cancer-related fatigue 1.
From the Research
Laboratory Tests for Chronic Fatigue and Diffuse Pain
- The following laboratory tests may be used to evaluate chronic fatigue and diffuse pain:
- Complete Blood Count (CBC) test to assess disease activity and prognosis in rheumatic disorders 2
- Vitamin D status to examine whether chronic fatigue syndrome/myalgic encephalomyelitis is associated with altered circulating vitamin D metabolites 3
- Cardiorespiratory fitness and neuromuscular function tests to determine the differences in fitness and function between people with chronic fatigue syndrome (CFS) and fibromyalgia syndrome (FMS) and healthy individuals 4
- Vitamin and mineral status tests to determine whether deficiencies in vitamins and minerals contribute to symptoms in CFS and FMS patients 5
Specific Laboratory Tests
- CBC-derived inflammatory biomarkers such as Neutrophil-to-Lymphocyte Ratio (NLR) to assess disease activity and response to treatment in Rheumatoid Arthritis (RA) 2
- Mean Platelet Volume (MPV) and NLR to determine the prognosis of renal involvement in Systemic lupus erythematosus (SLE) 2
- Red cell distribution width (RDW), MPV, NLR, and platelet to lymphocyte ratio (PLR) as inflammatory biomarkers with a prognostic role in rheumatic disorders 2
- Liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis to measure total 25(OH) vitamin D concentrations in serum 3
Limitations and Findings
- Poor study quality and substantial heterogeneity in most studies were found, and no vitamins or minerals have been repeatedly or consistently linked to clinical parameters in CFS and FMS patients 5
- No evidence of a deficiency in serum total 25(OH) vitamin D was evident in individuals with CFS/ME, and low serum concentrations of total 25(OH)D do not appear to be a contributing factor to the level of fatigue of CFS/ME 3
- Lower cardiorespiratory fitness and neuromuscular function were found in CFS and FMS compared to healthy controls, with moderate to high effect sizes 4