A PINT isn’t a lot. In fact the amount of blood donated at each sitting is 470 millilitres per person, so not even a pint. Yet it could save up to three lives. NHS Blood and Transfusion is appealing for more black and ethnic minority donors. Yet this isn’t some form of racism, but a reflection of the fact that black donors are more likely than white donors to have blood with the rare Ro-subtype.

This is required for the treatment of sickle cell disease, itself much more common among the black population.

Although one in four of us will need a blood or blood product transfusion at some point in our lives, NHS Blood and Transfusion (NHSBT) estimates that less than five per cent of those eligible in the UK actually donate blood. Worryingly there is often less than a week’s supply left in the blood banks at any one time.

There are four basic blood groups, A, AB, B and O, reflecting the markers on the surface of the red blood cells. On top of this, individuals are Rhesus positive or Rhesus negative. If you are O negative, you have no markers whatsoever, and hence your blood could be donated to anyone. This would typically happen in an emergency setting. Yet blood donors of all types are needed as only seven per cent of the country is O negative.

When blood is donated it is broken down into its three major components, red cells, which can last for 35 days, platelets which keep for a week, and plasma with a shelf life of three years.

Blood and its products is used in a multitude of ways. Roughly two thirds is utilised in the treatment of cancer, anaemia and other blood disorders. One quarter is used in surgery both in the emergency setting, but also for routine procedures, notably heart surgery. Around five percent is used to treat blood loss after childbirth, where large volumes can often be consumed in a very short space of time.

Blood donation is open to any suitable person between the ages of 17-66, and if you have previously donated, you can continue up to the age of 70, health permitting. Eligibility criteria are broad to encourage donation, yet at the same time if there is any concern that you or a partner have any form of blood-borne illness, notably HIV or hepatitis, you must not donate until you are confirmed not to have either infection.

The process of donation itself is relatively simple. You can register either online at blood.co.uk or by calling 0300 123 23 23. Once signed up, you can select from 23 permanent donor centres and several mobile units. The process itself is no more painful than a needle being inserted into your arm, with blood collection lasting five-ten minutes. You shouldn’t feel any ill effects; most people are able to continue as usual after donation. During this season of good will, donating blood might be one of the most selfless acts you could perform.

Ask Dr Zak

Question: I’m worried that my baby’s head is flat on one side. He’s five months old. I’ve heard that helmets can help. Is that true?

Answer: Flat head syndrome, where the head is flattened across the back of the head, or just on one side, is fairly common, affecting around 20 per cent of babies. It is perhaps now more prevalent as parents are encouraged to place children on their backs when they go to sleep. It may be that this extra time resting on the back of the head contributes to it. However positioning your child on their back has been shown to reduce the risk of cot death, so please do not alter this.

The skull is still soft at this point and by encouraging your baby to move their head around, and encouraging “tummy time”, you might be able to take the pressure off this one spot. That being said, the majority improve with time. It is also worth bearing in mind that the child will develop more hair on their head as they grow older, and any defect will be less noticeable. Although helmets are available, there is limited evidence to recommend their use, and they may be distressing for your baby.

Question: I took my 13-year-old daughter to the GP to discuss treatment for her heavy periods. I was quite shocked when he suggested a contraceptive pill. Is this right? Sharon

Answer: Our female children are starting their periods earlier than in previous generations, in part due to better standards of living and nutrition. Hence what we would have considered “adult issues” are arising when many still see their teenage daughters as children. It sounds like your daughter is suffering from dysfunctional uterine bleeding, where there is no abnormality of her womb, but her periods are heavy and hence troublesome. A hormonal contraceptive, usually the combined pill, is offered first line. This should regulate the length of her cycle as well as reduce bleeding and hopefully make the experience less painful. There is no evidence to suggest that this is more likely to encourage early sexual activity, which is often a parent’s unspoken fear.

If you have a question for Dr Zak, please email: askdoctorzak@gmail.com

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Dr Uddin’s advice is provided in good faith and in accordance with currently accepted evidence. However, this content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. You should always seek the advice of a GP, or other qualified health provider, regarding a medical condition.