Step 1: Rule out other causes
Many conditions can look like ME/CFS. A standard exclusion panel includes:
- Full blood count (FBC)
- Iron studies, B12 and folate
- Electrolytes and kidney function (U&E)
- Liver function (LFT)
- Inflammation markers: CRP and ESR
- Thyroid (TSH)
- HbA1c (diabetes)
- Coeliac screen
- Sleep apnoea screening. See Sleep.
Step 2: Extra tests worth requesting
| Test | Why |
|---|---|
| Iron studies (ferritin, saturation) | Ferritin under ~50 can matter for fatigue even if the lab flags it as “normal” |
| 8–9 am cortisol | A mildly low morning cortisol is one of the most replicated findings in ME/CFS. It was also the standout marker in a Yale Long COVID study. It must be taken at the right time of day. |
| Vitamin D | Deficiency is common |
| ANA / ENA | Autoimmune screen |
| Immunoglobulins (IgG, IgA, IgM) | Immune function |
| EBV serology (VCA IgM, VCA IgG, EBNA, EA) plus CMV | Checks for viral reactivation, especially if your illness began after glandular fever |
| CK (creatine kinase) | Marker of muscle damage |
| LD (lactate dehydrogenase) plus LD isoenzymes | A general “cell stress” and energy metabolism marker. Isoenzymes show which tissue it’s coming from. |
| Haptoglobin and reticulocytes | Rules out red blood cell breakdown if LD is raised |
| Tryptase | If you have flushing, itching or food reactions (mast cell problems often come with ME/CFS) |
| Carnitine (free/total) and acylcarnitine profile | Before taking carnitine. A documented deficiency is needed for injectable carnitine. |
Also tell your doctor about any recent infections (COVID reinfection is a very common relapse trigger) and any recent medication or hormone changes.
How to read common results
“Everything came back normal”
That’s useful information. Very low CRP and ESR (no general inflammation) with otherwise normal bloods is the classic ME/CFS picture. It helps rule out other illnesses, and it doesn’t mean nothing is wrong.
LD (lactate dehydrogenase)
LD is an enzyme in almost every cell. It leaks into the blood when cells are stressed or damaged, so it’s a non-specific “something is turning over” marker. A raised LD can come from:
- Liver: check ALT, AST, GGT and bilirubin
- Red blood cell breakdown: check haemoglobin, bilirubin, haptoglobin and reticulocytes. A damaged sample can fake a single high result, but not a steady rise across several tests.
- Muscle: check CK
- Viral infection or reactivation: EBV in particular raises LD
- A shift to anaerobic energy production. This is the ME/CFS-relevant explanation (see the “two engines”).
- Rare serious causes. Very unlikely if your full blood count is normal and your CRP/ESR are very low, but it’s why labs suggest follow-up tests.
A mild, steadily rising LD over several years, with normal liver tests, is worth tracking. It can act as an objective marker. If pacing and treatment are helping, it should stabilise or fall.
CK vs LD
| Result | Points to | Next step |
|---|---|---|
| CK high + LD high | Muscle is the source: over-exertion, a muscle condition, or a medication (e.g. a statin) | Neurology or rheumatology review if CK is well above range |
| CK normal + LD high | Not muscle damage. More likely viral reactivation or the anaerobic energy shift. | EBV/CMV serology, LD isoenzymes |
Exercise raises CK for 2–3 days, so avoid strenuous activity before the test.
Cortisol
A random or afternoon cortisol can’t show the ME/CFS pattern (afternoon normal range is roughly 100–400 nmol/L). Only a test taken between 8 and 9 am shows the blunted morning cortisol.
B12
A total B12 in the low-normal range (under about 330 pmol/L) can be inconclusive. Ask for active B12 (should be above 35 pmol/L) and homocysteine (rises if you’re functionally deficient). If both are normal, your stores are fine.
Iron
Iron and saturation dip in the afternoon, so an afternoon test underestimates them. Once ferritin is adequate (~50+) and saturation is normal, pushing ferritin higher won’t add energy.
If you take creatine
Creatine slightly raises serum creatinine. Tell your doctor so it isn’t mistaken for a kidney problem.
Private “longevity” blood panels
Private panels (such as Everlab in Australia, roughly $299–$2,700) test dozens of markers. They’re not an ME/CFS workup:
- They usually don’t include autonomic testing, timed morning cortisol, EBV/CMV reactivation serology, tryptase or proper autoimmune panels.
- A GP can order most of the same blood tests on Medicare.
- Avoid VO₂ max testing. It’s a maximal exercise test and a known PEM trigger.
- Ignore any plan that tells you to “increase training load”.
A script for your GP appointment
Brain fog makes appointments hard. Copy this, edit it to suit you, and take it with you or send it ahead.
- “My symptoms fit ME/CFS and I’d like to rule out things that commonly sit alongside it.”
- “Could we do an 8–9 am cortisol, full EBV serology (VCA IgM and IgG, EBNA, early antigen) plus CMV, iron studies, vitamin D, ANA and immunoglobulins?”
- “If my LD is raised: a repeat LD with CK and LD isoenzymes, plus haptoglobin and reticulocytes, so we can see where it’s coming from.”
- “I get lightheaded when I stand. Here are my lean test numbers. Could I be referred to cardiology or an autonomic clinic?”
- “Could I get a referral for a home sleep study? If I don’t meet the Medicare criteria, I’m happy to pay for a Level 2 study.”
- “Can we set up a Chronic Condition Management Plan so I can see an occupational therapist who understands pacing?”
- “I’d like to discuss a trial of low-dose naltrexone for three months, starting low and building up slowly, while I keep a symptom log.” (If declined: “Is there a colleague who prescribes it, or could you refer me?”)
- “I’ve started creatine, so my creatinine might read slightly high.”
If your GP pushes back, it can help to say: “I understand it isn’t urgent. I want to understand what’s driving my symptoms because it changes how I manage the ME/CFS.”
Looking for an ME/CFS-experienced GP? See Find a doctor. Emerge Australia also keeps a list. See Getting care in Australia.