More and more, recently, it has been claimed that HPU is merely a new name for KPU. In this way, some laboratories claim that KPU tests and HPU tests are interchangeable, which is untrue. This claim is misleading and may result in some customers carrying out a test that which they do not need. Furthermore, a certain HPU test called “haemopyrrollactam test” is also being marketed, which is actually a simple KPU-test and not a true HPU-test. The HPL-complex that is excreted in the urine can only be determined in the laboratory with elaborate methods of investigation, and the cost of this is between 50-65 GBP. If an HPU test offered for 25 GBP or less, then you can be certain that this is not a true HPU test, but another test.
Therefore, it is clear that HPU and KPU are not one and the same thing. An analogy would be as if it was said that D-lactate, which causes death from acidosis if the concentration in the blood is too high e.g. Short Bowel Syndrome, were the same as L- lactate, which is simply metabolised at high concentrations or in lactose intolerance, causing only diarrhoea and gas formation.
Malvaria (HPL) or mauve factor is often mistakenly referred to as kryptopyrrole (KP) or pyrroluria. This is due to studies incorrectly classifying mauve factor and KPU as the same substance, owing to similarities in the chemical structure. Mauve factor or hydroxyl-haemopyrrolin-2-one (HPL) is produced from hydroxylactam or haemopyrrole and not of kryptopyrrole. Therefore the terms pyrroluria and kryptopyrrole should not be used interchangeably to refer to mauve factor or malvaria. Clinical Naturopathy an evidence-based guide to practice J. Sarris and J. Wardle 2nd Edition (2014) Elsevier Australia.