One.
One.

Platform

Company

Resources

Create Account

One Health helps you track and understand your health simply.

Create Account

One Health helps you track and understand your health simply.

Total Hemoglobin (Venous)

Immunology & Autoimmune

tHb VenTotal hemoglobin (venous)

Review status

Currently under review

Pending specialist review and validation.

What it shows

This test measures the amount of hemoglobin in a venous blood sample. Hemoglobin is the iron-containing protein inside red blood cells that carries oxygen from your lungs to the rest of your body and helps return carbon dioxide back to the lungs. Measuring total hemoglobin reflects your blood’s oxygen-carrying capacity.

It may be performed as part of a complete blood count or on a blood gas or co-oximetry panel when rapid assessment is needed. Results are interpreted along with other blood measurements and your clinical situation.

Why it matters

Your hemoglobin level helps your care team evaluate symptoms such as fatigue, shortness of breath, dizziness, chest discomfort, or paleness. It is central to assessing anemia and conditions that cause too few or dysfunctional red blood cells. It also assists in monitoring recovery after bleeding, surgery, or medical treatments that affect blood production.

Clinicians use this test to guide decision-making in emergency and inpatient settings, during pregnancy care, and in chronic conditions such as kidney disease, inflammatory disorders, and lung or heart disease. It can also inform transfusion decisions and track how well treatments are working.

Understanding your results

A lower-than-expected hemoglobin can be due to iron deficiency, chronic illness, kidney problems, vitamin deficiencies, inherited blood conditions, or recent blood loss. A higher-than-expected result can be related to dehydration, smoking, living at high altitude, lung or heart conditions, or bone marrow disorders. Your clinician will consider your symptoms, medical history, vital signs, and other lab values before drawing conclusions.

If your result is outside the expected range, your clinician may repeat the test, check red blood cell indices, iron studies, kidney function, or evaluate for inflammation or bleeding. Small, isolated changes often reflect hydration or collection factors, while persistent changes may prompt targeted testing or treatment. Do not change medications or supplements without medical advice.

Reference ranges

135 – 195 g/L
Female
0 days – 1 day
135 – 195 g/L
Male
0 days – 1 day
0 – 0.02 fraction
All sexes
0 days – 150 years
135 – 185 g/L
Female
1 day – 7 days
135 – 185 g/L
Male
1 day – 7 days
100 – 180 g/L
Female
7 days – 1 month
100 – 180 g/L
Male
7 days – 1 month
95 – 135 g/L
Female
1 month – 6 months
95 – 135 g/L
Male
1 month – 6 months
105 – 135 g/L
Female
6 months – 2 years
105 – 135 g/L
Male
6 months – 2 years
115 – 135 g/L
Female
2 years – 4 years
115 – 135 g/L
Male
2 years – 4 years
115 – 155 g/L
Female
4 years – 10 years
115 – 155 g/L
Male
4 years – 10 years
120 – 160 g/L
Female
10 years – 21 years
130 – 160 g/L
Male
10 years – 21 years
120 – 160 g/L
Female
21 years – 150 years
135 – 175 g/L
Male
21 years – 150 years

Reference intervals vary by laboratory, analyzer, methodology, population, and units. The ranges shown here are for education only. Always interpret your results against the reference interval printed on your own lab report.

Factors that could impact Total Hemoglobin (Venous)

  • Hydration and IV fluids

    Dehydration can concentrate the blood and raise hemoglobin, while recent intravenous fluids can dilute the sample and lower the value. Let your clinician know about recent fluid intake or IV therapy.

  • Sample collection issues

    Drawing blood from an arm with an IV running, prolonged tourniquet time, or sample mix-ups can alter results. Proper collection technique and avoiding draws from infusion lines help ensure accuracy.

  • High altitude and smoking

    Living at higher elevations or smoking can increase hemoglobin as your body adapts to lower oxygen availability. This physiologic effect is considered when interpreting your result.

  • Recent blood loss or transfusion

    Bleeding, surgery, donation, or transfusion can change hemoglobin quickly. Timing of the test relative to these events affects interpretation and may warrant repeat testing.

  • Medications and hormones

    Erythropoiesis-stimulating agents, testosterone, chemotherapy, and some antibiotics can raise or lower hemoglobin by affecting red blood cell production or survival. Provide a full medication list.

  • Pregnancy and early infancy

    Normal hemoglobin changes occur during pregnancy and in young infants due to physiologic shifts in plasma volume and red cell production, so age and pregnancy status are important for context.

  • Chronic health conditions

    Kidney disease, inflammatory disorders, thyroid disease, nutritional deficiencies, and bone marrow conditions can influence hemoglobin. Managing the underlying condition often improves levels.

2026

References

  1. McGill University Health Centre. (2015, July 03). tHb Ven (Task CD 1089328). Laboratory reference ranges.
  2. McGill University Health Centre. (2018, September 24). tHb Ven (Task CD 1088724). Laboratory reference ranges.
  3. McGill University Health Centre. (2019, January 16). tHb Ven (Task CD 1088724). Laboratory reference ranges.
  4. World Health Organization. (2011). Haemoglobin concentrations for the diagnosis of anaemia and assessment of severity. Geneva, Switzerland: WHO.
  5. Carson, J. L., Guyatt, G., Heddle, N. M., Grossman, B. J., Cohn, C. S., Fung, M., ... Roback, J. D. (2016). Clinical practice guidelines from the AABB: Red blood cell transfusion thresholds and storage. JAMA, 316(19), 2025-2035.