Hereditary coproporphyria (HC) is a rare disease originating from detrimental changes in the gene of the mitochondrial enzyme coproporphyrin-III oxidase (CPO). The enzyme malfunction results in pathologically high urine concentrations of porphobilinogen and 5-aminolevulinic acid. There is no cure for hereditary coproporphyria but a carbohydrate-rich diet, as well as general drug and alcohol abstinence, reduce the risk of acute porphyria attacks.
Hereditary coproporphyria is passed on in an autosomal dominant manner. It is caused by a set of mutations of the CPOX gene which drastically downregulates the enzymatic activity of CPO. CPO is involved in porphyrin and heme biosynthesis  .
Hereditary coproporphyria can develop in an acute and a chronic form. In its acute manifestation, patients may suffer from persisting nausea, vomiting attacks, severe epigastric abdominal and back pain lasting for several days, constipation, obstipation, cortical blindness, hypertension, hyponatremia, tachycardia, reddish urine and discrete seizure episodes, which can also lead to depression. Psychological symptoms typically present concomitantly with abdominal symptoms. Patients can also exhibit motor neuropathies characteristic of Guillain-Barré syndrome. Diffuse pain in the upper body has also been reported. Hereditary coproporphyria is usually asymptomatic between acute attacks.
In its chronic form, hereditary coproporphyria patients typically develop a long-lasting cutaneous photosensitivity in sun-exposed body parts such as hands and face. These body parts typically show a very fragile skin, hyperpigmented scars and bullae .
The probability of prevalence of the pathogenic CPOX mutations is equal in both, men and women. However, acute attacks affect women more often, in particular between menarche and menopause (age- 16 to 45). Attacks before puberty are very rare .
In the initial screening procedure, it is reasonable to probe 5-aminolevulinic acid and porphobilinogen urine levels, which are expected to be increased by at least a factor of three during attacks. Urine porphyrin concentrations are another viable cross-check. Importantly, urine porphyrin levels can reduce back to normal or remain mildly elevated between attacks  . Slightly increased but constant urine coproporphyrin levels are nonspecific and thus insufficient to corroborate the diagnosis. Serum sodium concentration should be checked in patients during attacks, since hyponatremia a quite common symptom. It is hardly feasible and advisable to directly measure the enzymatic activity of CPO.
Hereditary coproporphyria diagnosis mainly relies on solid evidence of elevated concentrations of coproporphyrins in the feces after a positive initial screening. Fecal coproporphyrin III levels can be up to 200 times higher than normal in absolute terms . A direct initial test of fecal coproporphyrin III levels without further backup tests lacks specificity and sensitivity. The ratio of fecal coproporphyrin III to coproporphyrin concentrations has been shown to be a suitable check to probe for hereditary coproporphyria in adults. A dominant contribution (60-95%) of the coproporphyrin III isomer in this ratio is characteristic of hereditary coproporphyria, while it is smaller than 50% in control groups  .
Abdominal pain symptoms in hereditary porphyria have been rationalized with elevated urine levels of the heme precursor molecule delta-aminolevulinic acid. Administration of hemin relieves pain symptoms during attacks because it inhibits the catalysis of delta-aminolevulinic acid by aminolevulinic acid synthase-1 .