Biochemical testing detects elevated levels of free PPIX in blood. Excess PPIX can be detected in the stool of some patients, but is not always present. As PPIX molecules are not water soluble the disease cannot be diagnosed from urine.
Anticoagulated blood should be sent to the laboratory using the precautions advised by the laboratory. As the PPIX molecule can be damaged by light, it is advisable to wrap the test-tube in aluminium foil to protect the blood from light during transportation.
Genetic diagnosis is performed by DNA analysis. The gene for the ferrochelatase enzyme, which shares the same name, is located on chromosome 18q21.3. The gene for the aminolevulinic acid synthase-2 enzyme is located on the X-chromosome.
It is common for patients to experience a significant delay in diagnosis and seek multiple medical opinions prior to arriving at a diagnostic confirmation of EPP. Cohort studies have shown that the average age at diagnosis ranges from 12-22 years, with many patients not diagnosed until much later in life.