What is a normal haemoglobin level?

Normal haemoglobin ranges vary by sex and laboratory. Typical reference ranges are: men 130–175 g/L (13.0–17.5 g/dL); women 120–155 g/L (12.0–15.5 g/dL); pregnant women 110–140 g/L (11.0–14.0 g/dL). Children's ranges vary by age. Your laboratory report will show your result alongside the specific reference range used by that lab — always compare your result against that reference range rather than a general figure.

What haemoglobin level indicates anaemia?

The World Health Organization defines anaemia as haemoglobin below 130 g/L (13.0 g/dL) in adult men, below 120 g/L (12.0 g/dL) in non-pregnant adult women, and below 110 g/L (11.0 g/dL) in pregnant women. Anaemia is classified as mild (100–119 g/L in women, 100–129 g/L in men), moderate (70–99 g/L), or severe (below 70 g/L). Severity guides the urgency and type of treatment your doctor will recommend.

What are the symptoms of low haemoglobin?

Common symptoms of low haemoglobin (anaemia) include fatigue and weakness, shortness of breath on exertion, pallor (pale skin, pale inner eyelids, pale nail beds), dizziness or lightheadedness, cold hands and feet, brittle nails, headaches, and difficulty concentrating. Symptoms depend on severity and how quickly the anaemia developed — a gradual decline is often tolerated with minimal symptoms at levels that would cause severe symptoms if they dropped rapidly.

Can I raise my haemoglobin naturally?

Whether dietary changes can raise your haemoglobin depends on the cause of the anaemia. If the cause is iron deficiency, increasing dietary iron (red meat, legumes, leafy greens, fortified cereals) combined with vitamin C (which improves iron absorption) may help — and iron supplement tablets are often required for faster correction. If the cause is B12 or folate deficiency, those specific nutrients need to be replaced. If the cause is chronic disease, kidney failure, or a bone marrow issue, dietary changes alone will not resolve it. Always establish the cause first before attempting self-treatment.

What does it mean if my haemoglobin is high?

A haemoglobin level above the normal range is called polycythaemia or erythrocytosis. Causes include dehydration (the most common and correctable cause), living at high altitude, smoking, lung disease that reduces oxygen exchange, sleep apnoea, and in some cases a bone marrow condition called polycythaemia vera. A single high result in the context of dehydration is usually not concerning, but persistently elevated haemoglobin requires investigation by your doctor.

Understanding Your Haemoglobin Result

Quick Answer: Your haemoglobin result measures the oxygen-carrying protein in your red blood cells; a normal level is roughly 120–155 g/L for women and 130–175 g/L for men. A result below these ranges indicates anaemia — meaning your tissues may not be receiving enough oxygen — and your doctor will investigate the underlying cause before deciding on treatment, which may include dietary changes, supplements, or further testing.

Haemoglobin is one of the most commonly measured values in routine blood tests, and a result outside the normal range is one of the most frequent reasons patients are asked to come back for a follow-up consultation. Despite this, many patients arrive at that follow-up unsure what their haemoglobin number actually means, what questions to ask, and what to expect next.

This guide explains what haemoglobin measures, how to interpret your result, what causes it to be low (anaemia) or high, and how to prepare for your follow-up appointment so you can make the most of the time with your doctor.

Haemoglobin is not a single standalone test — it is part of the Full Blood Count (FBC), one of the most common panels ordered in routine health screens. Understanding haemoglobin in the context of your other FBC values (red cell count, MCV, MCH, ferritin, and transferrin saturation) gives a more complete picture than the haemoglobin figure alone.

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1. What Does Haemoglobin Actually Measure?

Haemoglobin (Hb) is an iron-containing protein found inside red blood cells. Its job is to bind oxygen in the lungs and transport it to every tissue in your body, then carry carbon dioxide back to the lungs to be exhaled. Without adequate haemoglobin, your cells receive less oxygen than they need — leading to the symptoms of anaemia: fatigue, breathlessness, pallor, and poor concentration.

Your result is reported in grams per litre (g/L) or grams per decilitre (g/dL). These are the same measurement at different scales — g/dL is simply g/L divided by 10. A result of 125 g/L is the same as 12.5 g/dL.

Reference ranges vary slightly between laboratories and differ by sex because men generally have higher haemoglobin due to testosterone’s stimulatory effect on red blood cell production. Typical ranges are:

Adult men: 130–175 g/L (13.0–17.5 g/dL)
Adult women (non-pregnant): 120–155 g/L (12.0–15.5 g/dL)
Pregnant women: 110–140 g/L (11.0–14.0 g/dL) — lower is expected due to plasma expansion
Elderly adults: ranges are similar but mild anaemia is more common and not always treated unless symptomatic

2. What Does a Low Haemoglobin Mean — Understanding Anaemia

Anaemia is diagnosed when haemoglobin falls below the reference range. Severity is classified as:

Mild anaemia: 100–119 g/L in women, 100–129 g/L in men — often asymptomatic or causes only mild fatigue
Moderate anaemia: 70–99 g/L — significant fatigue, breathlessness on exertion, pallor; most patients notice clear symptoms at this range
Severe anaemia: below 70 g/L — may require urgent treatment; breathlessness at rest, chest pain, dizziness

The severity level informs urgency. Mild anaemia found incidentally on a routine screen is typically investigated at a follow-up appointment in weeks. Severe anaemia — particularly if acute — may require same-day hospital assessment.

Critically, a low haemoglobin is not itself a diagnosis. It is a finding that triggers further investigation into the cause. Treatment depends entirely on the underlying cause, not on the number alone.

3. The Most Common Causes of Anaemia

Your doctor will classify the type of anaemia based on additional FBC parameters — particularly the MCV (mean corpuscular volume, which measures the size of your red blood cells) — and supplementary tests:

Iron deficiency anaemia (most common globally): Caused by insufficient dietary iron, poor absorption (e.g., coeliac disease, post-bariatric surgery), or blood loss (heavy periods, gastrointestinal bleeding, frequent blood donation). Red cells are small (low MCV — microcytic anaemia). Ferritin and transferrin saturation will be low. Treatment: oral iron supplements, dietary changes, and identifying the source of blood loss if present.

If your doctor recommends iron supplementation, over-the-counter iron tablets (such as ferrous sulfate or ferrous fumarate) are available at pharmacies. An iron supplement taken with vitamin C significantly improves absorption. Iron supplement tablets are widely available online and in pharmacies across Singapore, Australia, and the US — but always confirm the right dose and formulation with your doctor first. (Affiliate link — we may earn a small commission at no extra cost to you.)

Vitamin B12 or folate deficiency anaemia: Red cells are large (high MCV — macrocytic anaemia). B12 deficiency is common in vegans, the elderly, and those on long-term metformin. Treatment: B12 injections or oral high-dose supplements; folate tablets.

Anaemia of chronic disease: Associated with chronic inflammation (rheumatoid arthritis, kidney disease, cancer, chronic infection). Red cells are usually normal sized. Iron stores are normal or elevated. Treatment targets the underlying condition.

Thalassaemia trait: Particularly common in ASEAN populations (SG, MY, TH, VN, PH) and South Asian communities. Mild anaemia with very small red cells (very low MCV), but ferritin is normal. Usually requires no treatment — but important to identify for family planning. If you are of Southeast Asian or South Asian descent and have a consistently low haemoglobin with a very low MCV despite normal iron, ask your doctor whether thalassaemia screening is appropriate.

4. Questions to Ask at Your Follow-Up

What type of anaemia do I have, and what is the cause?
What does my MCV and ferritin result suggest about the cause?
Do I need any additional tests — for example, an endoscopy to check for gastrointestinal bleeding, or a B12 level?
If you are recommending iron supplements, what dose and formulation? How long before my levels improve?
Are there foods I should eat more or less of?
What haemoglobin level are we aiming for, and when will you retest?
Is there a possibility I have thalassaemia trait, given my ethnicity?
Is this likely to affect my daily energy levels, exercise capacity, or work?

5. What to Bring to Your Follow-Up Appointment

Your blood test results — both the recent result and any previous results if you have them. Trends matter as much as single values.
A note of your symptoms — how fatigued you feel, whether you are breathless on exertion, any changes in your periods (in women), any signs of blood in stool or urine
Your medication and supplement list — including any iron, B12, or other supplements already taken; any medications that affect absorption (antacids, PPIs, metformin)
Diet information — brief note on whether you eat red meat, your main protein sources, and whether you follow any dietary restriction (vegan, vegetarian, halal, kosher, etc.)
Written questions — as listed above

6. Haemoglobin During Pregnancy

Anaemia in pregnancy is common because plasma volume expands faster than red blood cell production in the second trimester, diluting haemoglobin. Mild anaemia (110–119 g/L) is expected and does not typically require treatment beyond dietary attention. Moderate anaemia (below 100 g/L) in pregnancy is associated with increased risk of preterm birth and low birth weight and is treated with oral iron supplementation — and in some cases, intravenous iron infusion.

Pregnant women in Singapore should have routine FBC screening at their first antenatal visit (typically 10–12 weeks) and again at around 28 weeks. The Screen for Life programme and KKH / public hospital antenatal pathways include this screening. In Australia, routine antenatal FBC is covered under Medicare. In the US, anaemia screening is a standard component of prenatal care.

7. What to Expect After Treatment Begins

If iron deficiency is confirmed and oral iron supplements are started, haemoglobin typically begins to rise within 2–4 weeks of treatment. A recheck FBC is usually ordered 4–8 weeks after starting treatment to confirm response. Iron stores (ferritin) take longer to replenish — typically 3–6 months of treatment even after haemoglobin normalises, which is why it is important to complete the full course of iron therapy rather than stopping when you feel better.

Side effects of oral iron are common — nausea, constipation, and dark stools. Taking iron with food reduces nausea but also reduces absorption. Your doctor or pharmacist can advise on the best compromise. If side effects are intolerable, there are alternative formulations (slow-release, liquid, or lower-dose) that may be better tolerated.

Key Sources

This content is for general preparation purposes only and does not constitute medical advice. Always follow the guidance of your own healthcare provider. In an emergency, call 995 (Singapore), 000 (Australia), 911 (US/Canada), or 111 (New Zealand). Full Medical Disclaimer