- A blood test ANA (antinuclear antibody) is a screening marker for autoimmune activity, not a standalone diagnosis of any condition.
- A positive ANA result is relatively common in healthy people at low titres; the titre level and pattern matter as much as the positive or negative result itself.
- MCH (mean corpuscular haemoglobin) is a red cell index included in a full blood examination; it helps identify anaemia patterns related to iron, B12, or folate status.
- ENA (extractable nuclear antigen) testing is a follow-up panel ordered when an ANA is positive and a clinician wants to identify specific antibody subtypes.
- All three markers require clinical context to interpret. An abnormal result is a starting point for a conversation with your GP, not a conclusion.
What These Three Markers Actually Are
If you have recently received blood results with terms like blood test ANA, MCH, or ENA on the page and are not sure what you are looking at, you are not alone. These are three distinct markers that often appear together or in sequence during an autoimmune workup, yet each measures something fundamentally different.
This guide explains what each test measures, what causes results to fall outside the reference range, and what to do next if your result is flagged.
ANA: Antinuclear Antibody Test
What it measures
An ANA test detects antinuclear antibodies in your blood. These are proteins produced by the immune system that, in some circumstances, mistakenly target the nuclei of the body's own cells.[1] The test is used as a broad screening marker for autoimmune activity.
The result is reported in two ways: as a titre (a dilution ratio such as 1:80 or 1:160) and as a pattern (homogeneous, speckled, nucleolar, etc.). Both the titre and the pattern carry clinical meaning.[5]
What a positive result means
A positive ANA does not confirm a diagnosis. It tells a clinician that your immune system is producing antinuclear antibodies at a detectable level. At low titres (typically 1:40 to 1:80), a positive result is common in healthy individuals and is not necessarily clinically significant.
As the titre rises, the likelihood that the result is clinically meaningful increases. A titre of 1:160 or higher warrants further investigation, particularly if you have symptoms that suggest autoimmune activity.
What conditions are associated with ANA
A positive ANA at a significant titre is associated with a range of autoimmune conditions.[4] These include lupus (systemic lupus erythematosus), Sjogren syndrome, systemic sclerosis, and mixed connective tissue disease, among others. ANA is a screening tool, not a diagnostic one. A positive result leads to further testing, not a label.
When to see a GP first: If you have symptoms such as persistent joint pain, a butterfly-shaped facial rash, unexplained fatigue, dry eyes, or dry mouth alongside a positive ANA, book an appointment with your GP before seeking additional tests. These symptoms combined with a positive result require clinical assessment, not self-directed testing.
ANA titres: a quick reference
| Titre | General interpretation |
|---|---|
| Negative | No significant antinuclear antibodies detected |
| 1:40 to 1:80 | Low positive; common in healthy individuals |
| 1:160 | Moderate positive; may warrant further investigation |
| 1:320 or higher | High positive; associated with higher clinical relevance |
This table is a general guide only. Reference ranges vary between laboratories. Always read your result in the context of your laboratory's reference interval and your clinician's assessment.
MCH: Mean Corpuscular Haemoglobin
What it measures
MCH stands for mean corpuscular haemoglobin. It is one of the red cell indices reported as part of a full blood examination (FBE), and it measures the average amount of haemoglobin contained within a single red blood cell.[2] Haemoglobin is the protein that carries oxygen through the bloodstream.
MCH is closely related to MCV (mean corpuscular volume, which measures cell size) and MCHC (mean corpuscular haemoglobin concentration). Laboratories typically report all three together as part of a standard FBE. If you want a broader explanation of the full blood examination and what its components tell you, the guide on blood test FBE results is a useful companion read.
What causes a low MCH
A low MCH is most commonly caused by iron deficiency. When iron stores are depleted, red blood cells are produced with less haemoglobin inside them. This produces cells that are both smaller (low MCV) and paler (low MCH). The resulting pattern is described as microcytic, hypochromic anaemia.[2]
Other less common causes of a low MCH include thalassaemia trait and chronic disease states.
What causes a high MCH
A high MCH means each red blood cell contains more haemoglobin than average. This is most often associated with macrocytic anaemia, where red blood cells are larger than normal. Common causes include deficiency of vitamin B12 or folate, both of which are required for normal red cell production.[2]
Excess alcohol consumption is another recognised cause of elevated MCH, as it interferes with red cell maturation.
MCH reference range
| Result | Typical range (adults) |
|---|---|
| Low MCH | Below 27 picograms (pg) per cell |
| Normal MCH | 27 to 33 pg per cell |
| High MCH | Above 33 pg per cell |
Reference ranges vary slightly between laboratories. Always compare your result against the specific range printed on your report.
ENA: Extractable Nuclear Antigen Panel
What it measures
An ENA panel is a blood test that identifies specific antibodies against extractable nuclear antigens. These are proteins found within the cell nucleus that can become targets of the immune system in certain autoimmune conditions.[3]
ENA testing is not a first-line test. It is ordered as a follow-up when an ANA is positive and a clinician wants to identify which specific antibodies are present, as this helps narrow down the clinical picture.
The main ENA antibodies
The ENA panel typically includes several antibody subtypes. The most commonly tested are:
| Antibody | Associated conditions (indicative only) |
|---|---|
| Anti-Sm | Lupus (relatively specific) |
| Anti-Ro (SSA) | Sjogren syndrome, lupus, neonatal lupus |
| Anti-La (SSB) | Sjogren syndrome |
| Anti-Scl-70 | Systemic sclerosis (scleroderma) |
| Anti-Jo-1 | Inflammatory myopathies |
| Anti-U1 RNP | Mixed connective tissue disease |
The presence of any of these antibodies is clinically significant and requires specialist review. A negative ENA in the context of a positive ANA does not exclude autoimmune disease; it simply narrows the picture.[3]
When ENA testing is ordered
ENA testing is not part of a routine check. It is ordered when:
- Your ANA titre is 1:160 or higher
- You have clinical symptoms that suggest a connective tissue disorder
- Your clinician wants to characterise a positive ANA further before referring to a rheumatologist
Important: ENA results should always be reviewed by a GP or specialist alongside your ANA titre, clinical symptoms, and other relevant blood markers. Do not interpret ENA results in isolation.
How ANA, MCH, and ENA Fit Together
These three markers are often encountered in the same clinical conversation, but they are measuring very different things.
ANA and ENA are both autoimmune markers. ANA is the screening test; ENA is the follow-up panel that adds specificity when ANA is positive. MCH, by contrast, is a red cell index that reflects haemoglobin content and is part of routine blood count testing.
The connection between them in practice is that autoimmune conditions can cause anaemia (called anaemia of chronic disease or, in some cases, haemolytic anaemia), so an abnormal MCH may sometimes appear alongside autoimmune markers in the same workup. Your clinician will consider all results together rather than interpreting each one in isolation.
If you have received results showing changes across multiple markers and want to understand the broader picture, reviewing your full blood examination results alongside this guide may be helpful.
Getting Tested in Australia
Do you need a referral?
For many blood tests in Australia, including some autoimmune screens, you do not need a GP referral to get tested. Services like Honed Health allow you to order select tests directly, collect at a pathology collection centre, and receive results with plain-language explanations.
However, if your ANA or ENA results come back positive or abnormal, seeing a GP or specialist is the appropriate next step. Self-directed testing is a useful starting point for informed people, but it does not replace clinical assessment.
What to tell your GP
When you bring your results to your GP, it helps to note:
- Any symptoms you have been experiencing and for how long
- Your family history of autoimmune conditions
- Any medications you are currently taking (some medications can cause drug-induced ANA)
- Any recent infections, as these can temporarily affect results
FAQ
What does a positive ANA blood test mean?
A positive ANA means your immune system has produced detectable levels of antinuclear antibodies. It is a screening result, not a diagnosis. Low titres are found in a significant proportion of healthy people. The titre level, pattern, and your clinical symptoms all need to be considered together. Your GP will determine whether follow-up testing is warranted.
What is MCH in a blood test?
MCH stands for mean corpuscular haemoglobin. It measures the average amount of haemoglobin inside each red blood cell and is reported as part of a full blood examination. A low MCH often points to iron deficiency; a high MCH may suggest vitamin B12 or folate deficiency. Neither result is a diagnosis on its own, but both give useful directional information.
What is an ENA blood test used for?
An ENA panel is a follow-up test ordered when your ANA is positive. It identifies specific antibody subtypes such as anti-Ro, anti-La, and anti-Sm, each of which is associated with different autoimmune patterns. ENA testing helps clinicians and specialists characterise a positive ANA result more precisely.
Can you have a positive ANA and be completely healthy?
Yes. Research suggests that up to 20 per cent of healthy individuals return a low-titre positive ANA. A positive result at a low titre without any supporting symptoms is generally not cause for concern, but it should be noted in your health history and discussed with your GP if you develop relevant symptoms in the future.
Do I need a referral for an ANA blood test in Australia?
Not always. Some private pathology services and online health platforms allow you to order an ANA test without a GP referral. That said, if your result is positive at a significant titre, you will need a GP or specialist to interpret it in context and advise on next steps.
What conditions are linked to a positive ANA?
A positive ANA at a clinically significant titre is associated with conditions including lupus, Sjogren syndrome, systemic sclerosis, and mixed connective tissue disease, among others. It is important to remember that ANA is a screening marker, and its presence does not confirm any of these conditions. Further testing and clinical assessment are always required.
