Hemoglobin (HGB) Test: Normal Ranges & Levels

What is Hemoglobin (HGB)?

A 68-year-old man came into my clinic the other day, huffing and puffing just from walking to the exam room. “Doc, I’m exhausted climbing a single flight of stairs,” he said. His blood work later revealed a hemoglobin level of 9.2 g/dL — well below the normal range. That red flag led us to an underlying iron deficiency.

Hemoglobin (often abbreviated as HGB or Hb) is the iron-rich protein inside your red blood cells that carries oxygen from your lungs to every tissue in your body, and returns carbon dioxide back to be exhaled. Think of it as your body’s oxygen delivery truck. Without enough hemoglobin, your organs and muscles starve for oxygen, leaving you feeling tired, dizzy, or short of breath.

The LOINC standard code for this test is 718-7 (Hemoglobin [Mass/volume] in Blood).

Normal Hemoglobin Ranges by Age and Gender

Normal HGB levels vary depending on age, sex, and even altitude where you live. The table below shows typical reference ranges used in most laboratories.

These values can shift slightly depending on the lab’s equipment and the altitude of your residence. For instance, people living in high altitudes often have higher hemoglobin levels because the body compensates for lower oxygen in the air.

Why Your Doctor Orders a Hemoglobin Test

A hemoglobin test is usually part of a complete blood count (CBC) and is one of the first tests ordered when a patient reports fatigue, weakness, or pallor. In my practice, I also check HGB when monitoring chronic illnesses, before surgery, or when a patient has unexpected bruising or bleeding.

Common Reasons for Testing

• Screening for anaemia (low HGB) or polycythaemia (high HGB)
• Evaluating the severity of bleeding or trauma
• Monitoring treatment for iron deficiency, vitamin B12 deficiency, or chronic kidney disease
• Assessing response to cancer therapies that affect bone marrow

Low Hemoglobin (Anaemia): What It Means

Low HGB — medically termed anaemia — means your blood isn’t carrying enough oxygen. My patients often complain of feeling “washed out,” having cold hands and feet, or noticing that their heart races when they exert themselves.

Common Causes of Low HGB

• Iron deficiency: The most common cause worldwide, often from blood loss (menstruation, GI bleeding) or poor dietary intake.
• Vitamin deficiency: Low folate or vitamin B12 leads to megaloblastic anaemia.
• Chronic disease: Inflammation from arthritis, kidney disease, or cancer can blunt red blood cell production.
• Bone marrow failure: Conditions like aplastic anaemia or leukaemia.
• Haemolysis: Red blood cells are destroyed prematurely (e.g., sickle cell disease, autoimmune haemolytic anaemia).

Symptoms to Watch For

Shortness of breath on exertion, dizziness, headache, pale skin, brittle nails, and unusual cravings for ice or dirt (pica). If you have any of these, a simple blood test can quickly check your HGB.

High Hemoglobin (Polycythaemia): When More Isn’t Better

Occasionally I see a patient with a ruddy complexion and a hemoglobin level above 18 g/dL. High HGB thickens the blood, increasing the risk of clots, stroke, or heart attack. It can be primary (polycythaemia vera, a bone marrow disorder) or secondary (a response to low oxygen).

Why HGB Can Be High

• Dehydration: Loss of plasma concentrates the blood.
• Chronic hypoxia: Smoking, lung disease (COPD), or living at high altitude.
• Polycythaemia vera: The bone marrow produces too many red cells without a known trigger.
• Erythropoietin abuse: Sometimes seen in endurance athletes using illegal performance enhancers.

Signs of Elevated HGB

Headache, blurred vision, itching (especially after a warm shower), and a feeling of fullness in the left upper abdomen (from an enlarged spleen).

Is High Hemoglobin Dangerous?

Yes, it can be. When HGB exceeds 17.5 g/dL in men or 15.5 g/dL in women and remains persistently elevated, the blood becomes sluggish. This increases the risk of deep vein thrombosis, pulmonary embolism, and stroke. If you have a high HGB, your doctor will look for the underlying cause and may recommend phlebotomy (removing blood) or medication.

Hemoglobin During Pregnancy

Pregnancy is a natural time of increased blood volume, which dilutes the red cells — so HGB falls slightly. Normal values dip to around 11–14 g/dL. I always tell my pregnant patients that mild anaemia is common, but a HGB below 10 g/dL needs investigation. Iron and folate supplements often help maintain healthy levels for both mother and baby.

How to Prepare for a Hemoglobin Test

No special preparation is needed for a simple HGB test. It can be done from a routine blood draw, either as a fingerstick or from a vein in your arm. I advise patients to stay well‑hydrated — dehydration can artificially raise HGB. If your doctor is also checking fasting glucose or iron, you may need to fast for 8–12 hours.

Treatment Options for Abnormal Hemoglobin

The treatment depends entirely on the root cause. For iron‑deficiency anaemia, oral iron supplements and dietary changes (red meat, spinach, fortified cereals) work wonders. Vitamin B12 injections help pernicious anaemia. For polycythaemia vera, low‑dose aspirin and periodic phlebotomy are first‑line therapies. Always work with your healthcare provider — don’t try to “boost” your hemoglobin with over‑the‑counter products without knowing why it’s low.

In my clinical practice, I often see patients who feel dramatically better just a few weeks after correcting a low HGB. One young woman who could barely finish her morning run became a marathoner once her iron levels were optimised. Your hemoglobin level is a vital sign — listen to what it’s telling you.