What does HPU have to do with haem?
With the metabolic disorder HPU (= haemopyrrollaktamuria), some of the 8 enzymes that produce haem do not work properly. The consequence of this: In addition to correctly produced haem, there is also haem that has some defects.
If our body was a car factory, it would be cars without a steering wheel or with a sliding roof on the floor instead of the ceiling. Since these cars are not exactly praiseworthy for the manufacturer, he wants to get rid of them quickly.
The same goes for the body. The wrongly assembled haem is toxic to the body. Therefore it makes some efforts to eliminate it as quickly as possible. An effective way is to attach vitamin B6 and zinc to the defective haem. Sometimes also a little manganese. All these substances make the defective haem water-soluble, so that it can be excreted via the kidneys and urine.