G6PD Test Report: Deficient, Normal and the Foods and Medicines

The answer up front: a G6PD report says whether your red blood cells have enough of one protective enzyme. “Normal” means no special limits. “Deficient” means certain foods, medicines and chemicals, fava beans above all, can burst red cells, so you’ll carry a list for life. Most people who are deficient stay well by avoiding those triggers, with a doctor guiding the details.

A newborn is a bit too yellow on day two. The paediatrician orders a bilirubin level and, alongside it, a G6PD screen. The result says “deficient”. The parents’ first question is usually: is this a disease? It’s better understood as a lifelong trait with a set of rules, and the rules are learnable, much like a food allergy that a family gets used to checking on every label, every new prescription and every visit to a new doctor or pharmacy. Manageable, truly.

What does the G6PD test measure?

Red blood cells carry oxygen around the body all day, and oxygen work creates wear and tear, a bit like rust. G6PD (glucose-6-phosphate dehydrogenase) is part of the cell’s rust-proofing. It keeps a protective supply topped up.

When G6PD is low, red cells cope fine on an ordinary day. Mostly unnoticed. Hit them with a strong trigger, though, and many burst at once. That burst is called haemolysis. It’s sudden. It causes sudden anaemia and jaundice, and it’s what the precautions are there to prevent.

The gene sits on the X chromosome. So boys and men who inherit it are usually clearly deficient, while girls and women can be fully deficient, partly deficient or carriers. It’s more common in families from South Asia, the Middle East, Africa and the Mediterranean, so a Pakistani or Indian family with one deficient son may find, once they start asking, that an uncle, a cousin or a grandfather also had a mysterious episode of dark urine years ago. Families share it.

Qualitative vs quantitative: how to read the report

One trap is timing. Straight after a haemolysis episode, the oldest, weakest red cells have burst and young cells, which carry more enzyme, remain. A test done then can look falsely normal. A recent blood transfusion causes the same problem, since the donor’s healthy cells are counted along with your own and quietly lift the average into the normal band for several weeks or even a few months afterwards. Tricky. Doctors often repeat the test a couple of months later. Our guide to why labs print different normal ranges explains how each lab sets its band.

G6PD in newborns

G6PD deficiency is one known reason a baby’s jaundice rises faster or higher than usual. The baby’s bilirubin is checked closely, and treatment such as phototherapy is started when the doctor’s charts say so. The levels by age in hours are covered in our newborn bilirubin report guide.

Parents of a deficient baby are usually told to keep naphthalene mothballs out of the house and away from baby clothes, since the fumes can trigger haemolysis. Many doctors also advise against henna (mehndi) on babies with G6PD deficiency. Breastfeeding mothers may be asked to avoid fava beans and certain medicines, and to check any new medicine with the doctor or pharmacist.

Foods and medicines to discuss with your doctor

Fava beans (broad beans, bakla)

This is the classic trigger, and the reason the condition was once called favism. The reaction can follow eating them fresh, dried or cooked, and cooking does not make them safe for a deficient person. Our broad beans (bakla) guide carries the same warning. Other daals and beans are generally fine, including chana, moong, masoor and rajma cooked the usual way, but if a relative has had a serious reaction or you are unsure about a particular bean sold under a local name at the bazaar, ask the doctor before it goes into the pot. Better safe.

Medicines and chemicals

Some antimalarials (primaquine and tafenoquine especially), some sulfa-type antibiotics, dapsone, rasburicase, methylene blue and naphthalene are well-known triggers. Lists differ by source and by the severity of the deficiency, so the safest habit is simple: tell every doctor, dentist and pharmacist “I have G6PD deficiency” before any new medicine. They’ll choose a safe option. Never stop or start a medicine on your own because of a list from the internet.

Malaria

Before a doctor prescribes primaquine or tafenoquine to prevent malaria from coming back, a G6PD test is usually needed. That’s a big reason this test appears in malaria-season clinics, where doctors in flood-hit districts may see many people with the relapsing type of malaria and need to know, before prescribing, whose red cells can safely handle the course. Sensible.

How to prepare for a G6PD test

1. No fasting is needed.
2. Tell the lab about any recent transfusion or recent episode of dark urine or jaundice, since both can give a falsely normal result.
3. If a malaria medicine is planned, have the test done before it is started, as the doctor directs.
4. Keep the report safely, and save a photo on your phone. It’s a lifelong result.
5. Share it with close relatives; brothers, sisters and children may want testing too.

More plain-English guides are in Lab Reports Decoded. The doctor who ordered the test is the right person to interpret it.

A few true facts

Did you know G6PD deficiency is among the commonest enzyme differences in the world, affecting hundreds of millions of people? Many never know unless they meet a trigger, which is why a child can grow up eating ordinary food without trouble and only discover the result after a plate of fresh bakla, a new antibiotic or a malaria course turns the urine dark.

Did you know it may have spread partly because it offers some protection against severe malaria? That’s why it’s so common in places where malaria has long been present.

G6PD report questions people ask