Every blood donation in India starts with one small test: a drop of blood, a copper-sulphate check or a meter, and a number, your haemoglobin. If it reads 12.5 g/dL or above, you can donate that day. Below it, you are politely deferred and asked to come back. This page explains what that number measures, why it protects you, and what to do if you keep missing it.
What haemoglobin actually does
Haemoglobin (Hb) is the iron-containing protein inside red cells that carries oxygen. More haemoglobin = more oxygen delivered per heartbeat. When Hb is low (anaemia) the classic signs are tiredness, breathlessness on stairs, paleness inside the eyelids, headaches, and a racing heart on small effort.
Normal ranges differ by sex: roughly 13–17 g/dL for men and 12–15 g/dL for women. The donor cutoff of 12.5 sits safely inside those ranges, it exists so that donating never pushes a person into anaemia.
Why women get deferred more often
Women’s iron stores are lower on average, menstruation costs iron every month, pregnancies cost more. That is the honest reason women see “Hb low today” more than men, and why the donation interval for women is 4 months instead of 3: the extra month protects iron stores. It is not weakness; it is arithmetic.
“My Hb was 11.9”, what now?
A single borderline reading is information, not a diagnosis. Common causes:
- Iron intake below need, the most common cause in India, especially on vegetarian diets.
- Donating or bleeding recently, periods, ulcers, piles.
- Recent illness, fevers, dengue and malaria all knock red cells down.
- Timing, Hb measured when dehydrated or at day’s end can read differently.
What to do: eat iron deliberately for a few weeks (below), retest at any camp or lab, and if readings stay low, see a doctor, persistent anaemia deserves a proper work-up, not another donation attempt. Donating with low Hb is bad for you and produces a unit that gets discarded anyway.
Keeping iron up (vegetarian-friendly)
Iron from plants (non-haem iron) absorbs better with vitamin C, and worse with tea and coffee:
- Lentils and beans, masoor, moong, rajma, chana.
- Dark greens, spinach, fenugreek, mustard leaves.
- Jaggery, dates, raisins, sesame, the traditional Assamese and Indian iron snacks, for good reason.
- Vitamin C alongside, lemon on dal, an orange or amla after meals.
- Tea/coffee an hour away from meals, not with them, tannins block iron absorption.
Non-vegetarians get an easier route: liver, red meat, eggs and fish carry highly absorbable haem iron.
The one-line summary
Haemoglobin is the oxygen railway; iron is the track material. The 12.5 rule keeps donors safe, low-Hb deferrals are the system working (not failing), and a plate of dal with lemon is genuinely medical advice.
Ready when your blood is: register as a donor →