Disruptions in haemoglobin synthesis may be hereditary or due to acquisition through environmental impacts or stress. These disruptions may result in increased concentrations of pyrroles in the urine. Some are more precisely called hydroxy hemopyrrollactamuria (HPU), because the body excretes excessive amounts of the substance hemopyrrolactam-complex (HPL) via the urine. HPL is a complex consisting of hydroxy-2,3-dimethylpyrrolidone-5-on and hydroxyhaemopyrrolinon-2-on complexed with pyridoxal-5-phosphate (active vitamin B6) and the minerals zinc and manganese. HPU is primarily believed to be linked to hereditary factors. Whereas kryptopyrroluria (KPU) is believed to be more consistent with stress load and may increase in response to this.
HPU/KPU can also be described as a deficiency of vitamin B6. Due to this deficit, the body reduces levels of zinc, chromium, and, to a lesser degree, manganese and magnesium. Active vitamin B6 plays a role in the production of vitamin B3 from the amino acid trytophan, therefore decreased B3-levels are also often seen in HPU/KPU. The extent of these nutritional deficiencies may not be adequately remedied by dietary adjustment alone. Specific supplementation strategies are usually required.