Lipoprotein abnormalities in patients with asymptomatic acute porphyria

There have been discrepancies in reports of total cholesterol and low density lipoprotein (LDL)-cholesterol levels in patients with acute porphyria. Some studies have found that acute porphyria patients have increased levels while others do not. The aim of this study has been to evaluate the lipid profile in a series of patients with acute porphyria, in order to help clarify these differences. Serum lipoprotein levels were studied in 30 patients (25 women and five men; age:38+/-10 years) with asymptomatic acute porphyria. Controls were 30 healthy volunteers matched for age and gender. For 13 patients and 15 controls, lipoprotein lipase and hepatic lipase activities were determined. Patients exhibited increased levels of total-cholesterol, LDL-cholesterol, high density lipoprotein (HDL)-cholesterol and apolipoprotein (apo)-A1 compared with controls (P4 mmol/l in 15 patients (50%). Levels of total triglycerides, very low density lipoprotein (VLDL)-triglycerides, VLDL-cholesterol, apo-B and lipoprotein(a) were similar in patients and controls. The hepatic lipase activity tended to be lower in patients than controls (33.8+/-17.7 vs. 50.4+/-23.0 pkat/ml; P=0.05). In conclusion, in patients with asymptomatic acute porphyria an increase of total and LDL-cholesterol was found. The cardiovascular risk conferred by this factor may be attenuated by increased HDL-cholesterol and apo-A1.

Alcohol and porphyrin metabolism

Alcohol is a porphyrinogenic agent which may cause disturbances in porphyrin metabolism in healthy persons as well as biochemical and clinical manifestations of acute and chronic hepatic porphyrias. After excessive consumption of alcohol, a temporary, clinically asymptomatic secondary hepatic coproporphyrinuria is observable, which can become persistent in cases of alcohol-induced liver damage. Nowadays, the alcohol-liver-porphyrinuria syndrome is the first to be mentioned in secondary hepatic disturbances of porphyrin metabolism. Acute hepatic porphyrias (acute intermittent porphyria, variegate porphyria and hereditary coproporphyria) are considered to be molecular regulatory diseases, in contrast to non-acute, chronic hepatic porphyria, clinically appearing as porphyria cutanea tarda (PCT). Porphyrins do not accumulate in the liver in acute porphyrias, whereas in chronic hepatic porphyrias they do. Thus, chronic hepatic porphyria is a porphyrin-accumulation disease, whereas acute hepatic porphyrias are haem-pathway-dysregulation diseases, characterized in general by induction of delta-aminolevulinic acid synthase in the liver and excessive stimulation of the pathway without storage of porphyrins in the liver. The clinical expression of acute hepatic porphyrias can be triggered by alcohol, because alcohol augments the inducibility of delta-aminolevulinic acid synthase. In chronic hepatic porphyrias, however, which are already associated with liver damage, alcohol potentiates the disturbance of the decarboxylation of uro- and heptacarboxyporphyrinogen, which is followed by a hepatic accumulation of uro- and heptacarboxyporphyrin and their sometimes extreme urinary excretion. Especially in persons with a genetic deficiency of uroporphyrinogen decarboxylase, but also in patients with the so-called sporadic variety of PCT, alcohol is able to transform an asymptomatic coproporphyrinuria into PCT. Alcohol has many biochemical and clinical effects on porphyrin and haem synthesis both in humans and laboratory animals. Ethanol suppresses the activity of porphobilinogen synthase (synonym: delta-aminolevulinic acid dehydratase), uroporphyrinogen decarboxylase, coproporphyrinogen oxidase and ferrochelatase, whereas it induces the first and rate-limiting enzyme in the pathway, delta-aminolevulinic acid synthase and also porphobilinogen deaminase. Therefore, teetotalism is a therapeutically and prophylactically important measure in all types of hepatic porphyrias.

Biochemical differentiation of the porphyrias

OBJECTIVES

To differentiate the porphyrias by clinical and biochemical methods.

DESIGN AND METHODS

We describe levels of blood, urine, and fecal porphyrins and their precursors in the porphyrias and present an algorithm for their biochemical differentiation. Diagnoses were established using clinical and biochemical data. Porphyrin analyses were performed by high performance liquid chromatography.

RESULTS AND CONCLUSIONS

Plasma and urine porphyrin patterns were useful for diagnosis of porphyria cutanea tarda, but not the acute porphyrias. Erythropoietic protoporphyria was confirmed by erythrocyte protoporphyrin assay and erythrocyte fluorescence. Acute intermittent porphyria was diagnosed by increases in urine delta-aminolevulinic acid and porphobilinogen and confirmed by reduced erythrocyte porphobilinogen deaminase activity and normal or near-normal stool porphyrins. Variegate porphyria and hereditary coproporphyria were diagnosed by their characteristic stool porphyrin patterns. This appears to be the most convenient diagnostic approach until molecular abnormalities become more extensively defined and more widely available.

Porphyria and its investigation

The porphyrias are inherited disorders of haem synthesis and must be considered in the differential diagnosis of numerous disorders.

Anaesthesia for porphyria

Porphyrias arise due to enzyme defects in the haem synthetic pathway. They are of concern to the anaesthetist as acute crises may be precipitated by anaesthetic drugs. Anaesthesia must be carefully managed in patients with porphyria in order to achieve a successful outcome.

Porphyrin enzyme analysis in an oral pathology practice: a look back over four years

The porphyrias are defined by specific enzymes having diminished activity. More enzymes have become available for routine testing. Measurement of urine and stool porphyrin and porphyrin precursor elevations are important, but in many instances are not found or found in confusing patterns. The use of enzyme analysis can often be helpful in identifying those patients with a genetically diminished enzyme activity level. Looking back over the last four years, modifications in evaluating patients for porphyria were developed and are related in this article. In 91 patients, patterns of enzyme deficiencies were seen that have been observed by others; however, new observations have been made. While many of the enzymes in the porphyrin pathway are available for testing, others need to come on line as soon as possible, particularly protoporphyrinogen oxidase.

[The porphyrias: it's definition, classification and differential diagnosis]

The porphyrias are diseases of enzyme deficiency in the heme synthetic pathway. They are classified into eight subtypes, two of which, ALADP and HEP, have been added as new subtypes during the past 10 years. These eight subtypes are divided into two groups, hepatic and erythropoietic. Hepatic porphyrias include AIP, ALADP, VP, HCP, PCT and HEP. Erythropoietic porphyrias consist of two subtypes, CP and EPP. From the clinical point of view, these subtypes may, also, be divided into acute and cutaneous porphyrias. AIP, ALADP, VP and HCP belong to acute porphyria. CP, EPP, PCT, and HEP to cutaneous porphyria. The diagnosis of porphyrias and differential diagnosis of subtypes are made by analyzing porphyrias and it's precursors in urine, blood and feces.

[A study of an automated porphyria diagnosis system using urinary porphyrin profile analysis]

Porphyrins are essential substances for the biosynthesis of heme. Porphyria results from a disorder in the metabolism of porphyrin. Patients suffering from Porphyria exhibit changes in their porphyrin profiles as measured in excretia and organs. A highly sensitive and simple analytical method using high-performance liquid chromatography (HPLC) for all porphyrin metabolites in urine was established. This method is able to separate porphyrins such as uroporphyrin, carboxylic acid porphyrins of hepta-, hexa-, penta-, and coproporphyrin isomers of I and III in a sample of human urine. In this study, the combination of HPLC with a computer system for automated porphyria diagnosis was investigated. The profile of all urinary porphyrins from patients with various Porphyria were measured by HPLC and diagnosed by the computer diagnostic system. This system enabled the estimation of 5 types of porphyrias with a high accuracy of diagnosis.

[Porphyrias and drugs]

The porphyrias are a metabolic disorders of heme biosynthesis characterized by the excessive production and excretion of porphyrins and porphyrin precursors. They are caused by defects in specific enzyme activities and classified into 7 subtypes. Some of them present with photosensitivity of skin and intermittent acute attacks related to nervous system disturbance. Especially in acute intermittent porphyria, patients have recurrent acute attacks of abdominal, neurologic, and psychiatric symptoms. Some precipitating factors; including drugs, hormonal factors, starvation, and stress; induces acute attacks. In this article, pathophysiology of the neurologic symptoms and relation between precipitating factors, especially focused in drugs, and acute attacks may be reviewed.

[Treatment of the porphyrias]

There are seven porphyrias which are caused by defective functions of the enzymes in the haem biosynthesis. The clinical classification of porphyrias are divided into three types which are neuroporphyria, neurocutaneous porphyria and cutaneous porphyria. For acute porphyric attack of neuroporphyria and neurocutaneous porphyria, the treatments of choice are administration of glucose and/or hematin, haem arginate and tinprotoporphyrin. Porphyria cutanea tarda in cutaneous porphyria is controlled by removal of iron by phrebotomies or low-dose chloriquine. A novel approach of intravenous administration of interferon may be useful to control the associated case of chronic hepatitis type C. Skin symptoms in erythropoietic protoporphyria can be alleviated with beta carotene. Hepatic failure due to protoporphyria may need a liver transplantation. Cimetidine, a H2-receptor antagonist, may be useful in the treatment of acute porphyric attack and in remission stage in neuroporphyrias, neurocutaneous porphyrias and cutaneous porphyrias such as porphyria cutanea tarda and protoporphyria.

Porphyria: reexamination of psychiatric implications

Acute intermittent porphyria mimics a variety of commonly occurring disorders and thus poses a diagnostic quagmire. Psychiatric manifestations include hysteria, anxiety, depression, phobias, psychosis, organic disorders, agitation, delirium, and altered consciousness ranging from somnolence to coma. Some patients develop psychosis similar to schizophrenia. Psychiatric hospitals have a disproportionate number of patients with this disorder as only difficult and resistant patients accumulate there. Presence of photosensitive porphyrins in the urine is diagnostic. When porphyrins are absent, excess of alpha aminolevulinic acid and porphobilinogen are present in the urine. The definitive test is to measure monopyrrole porphobilinogen deaminase in RBCs. This diagnosis should be entertained in the following situations: (a) unexplained leukocytosis; (b) unexplained neuropathy; (c) etiologically obscure neurosis or psychosis; (d) 'idiopathic' seizure disorder; (e) unexplained abdominal pain; (f) conversion hysteria, and (g) susceptibility to stress. Porphyria is important in psychiatry as it may present with only psychiatric symptoms; it may masquerade as a psychosis and the patient may be treated as a schizophrenic person for years; the only manifestation may be histrionic personality disorder which may not receive much attention. Diagnosis is based on a high index of suspicion and appropriate investigation. Various psychotropic drugs exacerbate acute attacks. While it is important not to use the unsafe drugs in porphyric patients, it is also imperative to look for this diagnosis in cases where these drugs produce unprecedented drug reactions.

Acute porphyrias: diagnosis and management

To summarize recent information about acute porphyrias and to provide clinicians with a practical diagnostic and management approach, we reviewed the pertinent literature and our clinical experience. The acute porphyrias are characterized by recurrent attacks of abdominal pain with or without additional manifestations of autonomic dysfunction or neuropsychiatric symptoms. On the basis of the potential of these disorders to affect the skin, they are further subdivided into neuroporphyrias and neurocutaneous porphyrias. During acute attacks, acute porphyria is always associated with increased levels of urinary porphyrin precursors. Between attacks, patients with neurocutaneous porphyrias may have normal urinary porphyrins; therefore, stool porphyrins, which are invariably increased, are the most helpful. Latent disease can be detected by the measurement of either urinary and stool porphyrins or cellular enzyme activity. Specific intravenous therapy with hematin has resulted in biochemical remissions, but its clinical benefit remains controversial. Measurement of urinary and stool porphyrins or porphyrin precursors is critical for the diagnosis of clinically overt acute porphyria. Enzyme assays are helpful in supporting the diagnosis but are best used to identify family members with latent disease. Preventive measures and supportive therapy are the mainstays of current management of patients with porphyria.

Composition of urinary coproporphyrin isomers I-IV in human porphyrias

The urinary distribution and relative proportions of the four coproporphyrin isomers I-IV were investigated in 50 patients suffering from hepatic and erythropoietic types of hereditary porphyrias. A highly efficient sample preparation method was applied to isolate urinary coproporphyrins, the isomer ratios of which were quantitated by isocratic ion-pair high-performance liquid chromatography. Results showed a significant decrease (p < 0.001) of the proportion of coproporphyrin I in acute hepatic porphyria (acute intermittent porphyria, hereditary coproporphyria, variegate porphyria, porphobilinogen synthase deficiency porphyria) as compared with chronic hepatic porphyria (porphyria cutanea tarda, chronic hepatic porphyria type B and C) (13.2 +/- 5.3%, mean +/- S.D., vs. 31.4 +/- 11.5%). Conversely, the proportion of isomer III was significantly higher (p < 0.001) in acute hepatic porphyria than in chronic hepatic porphyria (80.9 +/- 5.2% vs. 62.2 +/- 10.9%). As expected, the highest level of coproporphyrin I (90.0 +/- 1.9%) was found in congenital erythropoietic porphyria. The atypical coproporphyrins II and IV were detected in all types of porphyria analysed and ranged from 0.2 to 9.0%; no significant differences were seen between acute and chronic hepatic porphyrias. The diagnostic importance of the isomer ratios of coproporphyrins I and III has been confirmed in our study, while the significance of the atypical coproporphyrin isomers II and IV is still unclear at present.

[Alcoholic liver damage and impaired porphyrin metabolism]

The authors review the alcohol-induced acquired defect of the porphyrin metabolism. They think that the free radicals formed during the alcohol metabolism may have an important role in the producing of the enzyme defects and in the accomplishment of the acute attack in the genetic porphyrias. In the first part of the article they summarize the genetic hepatic porphyrias, main symptoms, the therapy and the mechanism of the free radical forming during the alcohol metabolism.

Clinical utility of fluorometric scanning of plasma porphyrins for the diagnosis and typing of porphyrias

The fluorometric emission scanning (using excitation at 405 nm) of plasma samples, simply diluted five-fold in phosphate-buffered saline, allows the differentiation of three conditions according to their porphyrin content. The emission maximum at 626-628 nm is a specific finding in variegate porphyria, while in erythropoietic protoporphyria a characteristic peak is found at 636 nm. A fluorescence emission maximum at 618-622 nm corresponds to a third group that includes normal subjects, non-porphyria patients and patients suffering from acute intermittent porphyria, hereditary coproporphyria, congenital erythropoietic porphyria (Günther disease) and porphyria cutanea tarda. Therefore, this simple, quick and cheap screening test allows one to establish whether a patient with a photocutaneous syndrome has porphyria and whether this porphyria belongs to the types: variegate, protoporphyria or other cutaneous porphyrias.