| Obligatory | Must not donate: If the estimated blood volume is less than 3.8 litres. |
| See if Relevant | Weight |
| Additional Information | It is recommended that no donor should lose more than 13% of their blood volume during any donation procedure. This is to protect them from adverse effects such as fainting and becoming anaemic. There is a minimum donor weight at which a donation can be accepted. This is not always appropriate. Obesity also makes it desirable to use factors in addition to the donor's weight to estimate their blood volume. Fat contains far less blood as a proportion of its weight than muscle. In obese individuals the blood volume can be seriously overestimated from weight alone. Overestimating a donor's blood volume makes it more likely that they will have an adverse incident. |
| Reason for Change | This is a new entry to take account of increasing levels of obesity. |