Fatigue

Fasting laboratory tests

• FBC
• Serum ferritin
• Fasting plasma glucose
• TSH

± depending on the clinical context

• hCGif neededPossible pregnancy.
• Creatine kinase (CK)if neededIn suspected myalgic encephalomyelitis/chronic fatigue syndrome (picture lasting 6 weeks or more), NICE ^[2] and INESSS ^[3] place creatine kinase among the baseline tests; EBM France classes it among the possible additional tests, depending on symptoms and history ^[4].
• Urine dipstick (protein, blood, glucose)if neededIn suspected myalgic encephalomyelitis/chronic fatigue syndrome (picture lasting 6 weeks or more), NICE ^[2] and INESSS ^[3] place urinalysis (dipstick: protein, blood, glucose) among the baseline tests; EBM France classes them among the possible additional tests, depending on symptoms and history ^[4].
• CRPif neededDepending on the clinical context. The source (EBM France) classes them under “other baseline tests, where appropriate”, depending on symptoms and history, without detail.
• ALTif neededDepending on the clinical context. The source (EBM France) classes them under “other baseline tests, where appropriate”, depending on symptoms and history, without detail.
• GGTif neededDepending on the clinical context. The source (EBM France) classes them under “other baseline tests, where appropriate”, depending on symptoms and history, without detail.
• Vitamin B12if neededDepending on the clinical context. The source (EBM France) classes them under “other baseline tests, where appropriate”, depending on symptoms and history, without detail.
• Serum creatinine with eGFRif neededDepending on the clinical context. The source (EBM France) classes them under “other baseline tests, where appropriate”, depending on symptoms and history, without detail.
• Serum electrolytesif neededDepending on the clinical context. The source (EBM France) classes them under “other baseline tests, where appropriate”, depending on symptoms and history, without detail.
• HbA1cif neededDepending on the clinical context. The source (EBM France) classes them under “other baseline tests, where appropriate”, depending on symptoms and history, without detail.
• Serum calciumif needednon-French guidelineIn suspected myalgic encephalomyelitis/chronic fatigue syndrome (picture lasting 6 weeks or more), NICE (2021) ^[2], the European EUROMENE consensus (2021) ^[5] and INESSS ^[3] place calcium and phosphate among the baseline tests, to rule out another diagnosis. EBM France lists serum calcium among the possible additional tests, reserved for cases where symptoms or history justify it, and does not cite serum phosphate ^[4].
• Serum phosphateif needednon-French guidelineIn suspected myalgic encephalomyelitis/chronic fatigue syndrome (picture lasting 6 weeks or more), NICE (2021) ^[2], the European EUROMENE consensus (2021) ^[5] and INESSS ^[3] place calcium and phosphate among the baseline tests, to rule out another diagnosis. EBM France lists serum calcium among the possible additional tests, reserved for cases where symptoms or history justify it, and does not cite serum phosphate ^[4].
• Total IgAif neededNICE proposes coeliac disease serology for anyone with prolonged fatigue (2015) ^[6] and includes it in the baseline tests for suspected myalgic encephalomyelitis/chronic fatigue syndrome ^[2]. In France, the HAS (2026) recommends this test for clinical signs of malabsorption, among which it cites asthenia ^[7], and EBM France lists it among the possible additional tests, depending on symptoms and history ^[4]. The result is reliable only on a gluten-containing diet, taken according to NICE at more than one meal a day for at least 6 weeks ^[6].
• IgA anti-tissue transglutaminase antibodies (tTG-IgA)if neededNICE proposes coeliac disease serology for anyone with prolonged fatigue (2015) ^[6] and includes it in the baseline tests for suspected myalgic encephalomyelitis/chronic fatigue syndrome ^[2]. In France, the HAS (2026) recommends this test for clinical signs of malabsorption, among which it cites asthenia ^[7], and EBM France lists it among the possible additional tests, depending on symptoms and history ^[4]. The result is reliable only on a gluten-containing diet, taken according to NICE at more than one meal a day for at least 6 weeks ^[6].