Joseph R. Bloomer

Recommendations for the Diagnosis and Treatment of the Acute Porphyrias

Key Summary Points Early Diagnosis of Acute Porphyria Consider in all adults with unexplained symptoms seen in acute porphyrias (Table 2); certain clinical features are suggestive: women of reproductive age; abdominal pain; muscle weakness; hyponatremia; and dark or reddish urine. Establish diagnosis promptly by testing for increased porphobilinogen in a single-void urine (we recommend the Trace PBG Kit [Thermo Trace/DMA, Arlington, Texas]). If porphobilinogen is increased, begin treatment immediately. To establish the type of acute porphyria, save the same urine sample for measurement of ALA, porphobilinogen, and porphyrin levels, and measure plasma porphyrin levels, fecal porphyrin levels, and erythrocyte porphobilinogen deaminase levels (Table 5 and Figure). Treatment of the Acute Attack Hospitalize patient for control of acute symptoms and withdraw all unsafe medications (see Table 3) and other possible precipitating factors. Provide nutritional support and symptomatic and supportive treatment; consider seizure precautions, especially if patient is hyponatremic; use medications that are known to be safe in the acute porphyrias; and use intravenous fluids to correct dehydration and electrolyte imbalances, narcotic analgesics for pain, phenothiazine for nausea or vomiting, and -adrenergic blockers for hypertension and symptomatic tachycardia. Begin hemin (3 to 4 mg/kg daily for at least 4 days) as soon as possible. Intravenous glucose alone (10%, at least 300 g daily) may resolve mild attacks (mild pain, no paresis, or hyponatremia) or can be given while awaiting delivery of hemin. Monitor patient closely: Check vital capacity (if impaired, place patient in intensive care) and neurologic status, including muscle strength (especially proximal); check serum electrolytes, creatinine, and magnesium levels at least daily; and watch for bladder distention. Follow-up Educate patient and family about the disease, its inheritance, precipitating factors, and important preventive measures. Encourage patients to wear medical alert bracelets and keep records of diagnostic studies and recommended therapy. Treat chronic manifestations (such as pain and depression) and disability. Provide access to genetic testing for patient and family members. The acute porphyrias are well-defined genetic disorders of heme biosynthesis characterized by acute life-threatening attacks of nonspecific neurologic symptoms (1). Although the specific enzyme and gene defects have been identified, diagnosis and treatment of these 4 disorders still present formidable challenges because their symptoms and signs mimic other, more common conditions. Delaying diagnosis and treatment of acute porphyric attacks can be fatal or can cause long-term or permanent neurologic damage. Updated, consistent recommendations for timely diagnosis and treatment of these disorders have been lacking, despite the existence of rapid, sensitive, and specific biochemical tests (2) and the availability of an effective therapy, which was first described more than 30 years ago (3) and was approved by the U.S. Food and Drug Administration (FDA) more than 20 years ago. Formation of an Expert Panel and Basis of Recommendations Concerns about misdiagnosis, delayed diagnosis, and inappropriate therapy prompted the American Porphyria Foundation to assemble a panel of experts on the acute porphyrias who were selected on the basis of their clinical and research experience and their contributions to the medical literature. The panel, which represents specialties including internal medicine, pediatrics, genetics, gastroenterology, hepatology, and hematology, was charged with formulating updated recommendations for diagnosing and treating the acute porphyrias. With support from the American Porphyria Foundation, the panel members convened for a day-long meeting to formulate clinical recommendations. Two members, assisted by a medical writer funded by the Foundation, prepared a draft manuscript based on the panels discussion and recommendations. All panel members participated in the review and revision of the manuscript and agreed to the final version. Recommendations are based on the clinical experience of the authors and their review of the literature. Because the acute porphyrias are rare, most of the literature consists of reviews, small series, and case studies. A detailed MEDLINE search on treatment of acute attacks, for example, revealed 71 papers (55 in English and 16 with English abstracts) published between 1966 and October 2004. Of these, 41 were single-case reports, 13 were case series of 10 or fewer patients, and 17 (11 in English) were studies with more than 10 patients (4-20). Altogether, 53 papers discuss more than 1000 patients who received hemin therapy with or without initial treatment with glucose. The American Porphyria Foundation partially funded this review. This nonprofit organization provides information and support to patients with porphyria and their physicians. It receives funding from private sources in addition to a nonrestricted grant from Ovation Pharmaceuticals, the manufacturer of hemin for injection (Panhematin), the only FDA-approved hemin therapy for the acute porphyrias. The Foundation and Ovation Pharmaceuticals had no role in the literature review, the formulation of recommendations, or the drafting and revising of the manuscript. Overview of the Acute Porphyrias Acute Porphyrias Are Inborn Errors of Heme Biosynthesis Each of the acute porphyrias results from the deficient activity of a distinct enzyme in the heme biosynthetic pathway (1). Porphyrias are classified as hepatic or erythroid, depending on whether most of the heme biosynthetic intermediates arise from, and accumulate in, the liver or in developing erythrocytes. They are also classified clinically as acute or cutaneous on the basis of their major clinical manifestations. Of the 5 hepatic porphyrias, 4 characteristically present with acute attacks of neurologic manifestationshence the designation acute porphyrias, a term that does not fully describe the clinical features, which can be prolonged and chronic. Table 1 shows the genetic and enzymatic features of the 4 acute hepatic porphyrias (21): acute intermittent porphyria, hereditary coproporphyria, variegate porphyria, and the very rare 5-aminolevulinic acid (ALA)dehydratase porphyria. The combined prevalence of these diseases is approximately 5 cases per 100000 persons (1). Numerous mutations have been identified for each disorder. The major manifestations of the acute porphyrias are neurologic, including neuropathic abdominal pain, peripheral neuropathy, and mental disturbances (Table 2) (1, 4, 22-25). These develop during adult life, are more common in women than in men, and are treated by methods to restore heme homeostasis. Variegate porphyria and, much less commonly, hereditary coproporphyria can also cause chronic, blistering lesions on sun-exposed skin that are identical to those in porphyria cutanea tarda, a much more common condition. Photocutaneous lesions may occur without neuropathic manifestations. Table 1. Characteristics of the 4 Acute Porphyrias Table 2. Common Presenting Symptoms and Signs of Acute Porphyria In addition to their highly variable neurologic signs and symptoms, the acute porphyrias are distinct from other porphyrias because of their common overproduction of the porphyrin precursors ALA (an amino acid), and porphobilinogen (a pyrrole). This striking biochemical feature is important for laboratory diagnosis and has implications for pathogenesis of the neurologic manifestations. While porphyrins (tetrapyrroles) are also increased, their measurement is of little value for initial diagnosis because they are also increased (in urine, feces, erythrocytes, or plasma) in other porphyrias and many other medical conditions. Pathogenesis of Acute Attacks The enzyme deficiency in each disorder is partial (approximately 50% of normal in the 3 most common acute porphyrias), and the remaining enzyme activity is usually sufficient for heme homeostasis. Because ALA dehydratase activity normally greatly exceeds that of the other enzymes in the pathway, a more severe deficiency of this enzyme (5% of normal) is required to cause manifestations of ALA-dehydratase porphyria. These enzymatic defects predispose the affected persons to the effects of precipitating factors, including many drugs (for example, barbiturates, anticonvulsants, rifampin, and progestins), endogenous steroid hormones (especially progesterone), fasting, dieting, smoking, and stress from illness, all of which can increase the demand for hepatic heme and induce synthesis of ALA synthase, the first enzyme in the heme biosynthetic pathway. Because hepatic ALA synthase is rate-controlling, production of heme pathway intermediates increases to the point at which the inherited partial enzyme deficiency becomes limiting, and intermediates accumulate in the liver. Porphobilinogen and ALA levels are increased in all patients with acute symptoms of these disorders and in some who are asymptomatic. The cause of hepatic overproduction of porphyrin precursors in the acute porphyrias is better understood than are the mechanisms for neurologic damage. Presumably, symptoms result primarily from the porphyrin precursors themselves rather than a deficiency of heme in nerve tissue (26, 27). Chronic symptoms and signs may reflect previous, unresolved neurologic damage. In the very rare cases of homozygous acute intermittent porphyria (26), variegate porphyria (28), and hereditary coproporphyria (29), severe neurologic manifestations begin in childhood. An allogeneic liver transplantation in a woman with heterozygous acute intermittent porphyria normalized her urinary ALA and porphobilinogen levels in 24 hours and completely eliminated her recurrent neurologic attacks, which supports the hepatic overproduction of porphyrin precursors in causing the neurologic symptoms (27). Si

Studies of bilirubin kinetics in normal adults.

This report describes studies of bilirubin kinetics in 13 healthy young adults. The plasma content of unconjugated bilirubin-(14)C was determined at frequent intervals for 24-30 hr after the intravenous injection of a tracer dose of unconjugated isotopic bilirubin. Fecal and urinary radioactivity were measured for 7 days. During this time cumulative recovery averaged 96% of the injected dose. The plasma curves were processed by digital computer. For the 30 hr experimental period, a sum of three exponentials, with average half-times of 18, 81, and 578 min, was required to describe the data. Using the plasma curve integral method, the hepatic bilirubin clearance (47 +/-10 ml/min, mean +/-SD), the bilirubin production rate (3.8 +/-0.6 mg/kg per day), and the mean red blood cell life span (101 +/-13 days) were calculated directly from the parameters of this function. To gain further insight into the metabolism of unconjugated bilirubin, the data were also used to determine the parameters of a multicompartmental model. In the model proposed, plasma unconjugated bilirubin exchanges with two additional pools one of which is thought to represent extrahepatic extravascular, and the other intrahepatic unconjugated bilirubin. Bilirubin is eliminated from the system via the proposed intrahepatic pool. From the data and the model, pool sizes and exchange rates between compartments were calculated, and the liver: plasma concentration gradient estimated. These studies provide a detailed analysis of the kinetics of unconjugated bilirubin in a healthy normal population and are intended to serve as a reference point for studies of abnormal states.

The Enzymatic Defect in Variegate Porphyria

Abstract Fecal protoporphyrin is increased in patients with variegate porphyria, even during clinical remission, suggesting an enzymatic defect in the terminal portion of the heme biosynthetic path...

Constitutional hepatic dysfunction (Gilbert's syndrome): A new definition based on kinetic studies with unconjugated radiobilirubin

Plasma clearance studies with unconjugated radiobilirubin were performed in eleven patients who had chronic unconjugated hyperbilirubinemia in the absence of structural liver disease. An abnormal clearance pattern, characterized by increased retention of isotope in the plasma at four hours (24.2±8.4 per cent, mean ± standard deviation; normal=5.0±1.9 per cent) and a reduction in hepatic bilirubin clearance (16±5 ml/minute; normal=47±10 ml/minute), was observed in all eleven cases, despite the fact that the mean red cell survival ranged from normal (112 days) to severely reduced (eleven days). Multicompartmental analysis suggests that the reduced hepatic bilirubin clearance is the result of a defect in both hepatic bilirubin uptake and conjugation. Twenty-one studies in a control group with anemia and/or hemolysis were indistinguishable from normal, indicating that neither of these factors was responsible for the abnormalities noted. These studies suggest that current diagnostic criteria for Gilberts syndrome, which exclude patients with hemolysis, will result in an artificial distinction among patients with the same basic hepatic abnormality.

Hepatic disease in erythropoietic protoporphyria

Two sisters had erythropoietic protoporphyria and a spectrum of liver disease. One (F.B.) died in hepatic failure within 3 months after the development of jaundice. Only 10 months before she died, she had exhibited only bromsulfalein retention and a borderline increase in serum transaminase. Surgical exploration because of the jaundice revealed patency of the bile ducts which was confirmed at autopsy. Wedge biopsy and autopsy specimens of liver showed an active cirrhosis with massive amounts of protoporphyrin in Kupffer cells, portal histiocytes, bile canaliculi and parenchymal cytoplasm. The other sister (L.R.) had never had symptomatic liver disease and only a slight increase in serum transaminase and bromsulfalein retention. On needle biopsy, the liver specimen showed portal inflammation with erosion of limiting plates, occasional bridging between triads and central areas of cell dropout. Protoporphyrin pigment was present in portal histiocytes, areas of central collapse and, more rarely, in parenchymal cytoplasm. These studies demonstrate that significant, progressive hepatic disease may occur insidiously in erythropoietic protoporphyria, and that once jaundice appears it may be followed rapidly by fatal hepatic failure.

Canalicular Bile Secretion in Man STUDIES UTILIZING THE BILIARY CLEARANCE OF [14C]MANNITOL

[(14)C]Mannitol was administered i.v. as a bolus injection to five postcholecystectomy patients with indwelling T-tubes and re-established enterohepatic circulations to evaluate the biliary clearance of [(14)C]mannitol as a means of estimating canalicular bile flow in man. [(14)C]Mannitol appeared in collections of bile 9-22.5 min after intravenous injection, rose to a peak, and thereafter paralleled the plasma [(14)C]mannitol disappearance curve. Bile-plasma [(14)C]mannitol ratios and [(14)C]mannitol clearances were determined during control and choleretic periods after correction of the bile [(14)C]mannitol points for the transit time of a given sample. After i.v. injection of sodium dehydrocholate in five studies, bile flow and mannitol clearance increased proportionately. However, when ductular secretion was stimulated with an i.v. bolus of secretin in three other studies, [(14)C]mannitol clearance remained essentially unchanged, indicating that [(14)C]mannitol entered bile at the level of the hepatocyte and could be utilized as a marker of canalicular flow in man. During control studies, when bile drained spontaneously from biliary fistulae in fasting patients, bileplasma [(14)C]mannitol ratios averaged 0.62+/-0.18 and canalicular flow, as estimated by [(14)C]mannitol clearance. (0.27+/-0.16 ml/min) accounted for 44-95% of total bile production (0.43+/-0.12 ml/min). When the rate of bile flow was plotted as a function of bile salt excretion after correction for the effects of biliary dead space, linear regression analysis revealed that approximately 7 mul of bile were secreted with each mumol of bile salt. Estimates of bile salt-independent canalicular flow accounted for at least one-third of the estimated 24-h bile production (604 ml) in these patients, indicating that this fraction of canalicular flow is a significant source of bile secretion in man.

Liver transplantation for erythropoietic protoporphyria liver disease

In erythropoietic protoporphyria (EPP), there is excessive production of protoporphyrin, primarily in the bone marrow, resulting in increased biliary excretion of this heme precursor. Some patients will develop progressive liver disease that may ultimately require liver transplantation. However, excessive production of protoporphyrin by the bone marrow continues after transplantation, which may cause recurrent disease in the allograft. This study was performed to define post‐transplant survival, the risk of recurrent disease, and specific management issues in patients transplanted for EPP liver disease. The patients studied consisted of twelve males and eight females, with an average age of 31 (range, 13‐56) years at the time of transplantation. The estimated maximum MELD score prior to transplant was 21 (range, 15‐29). Unique complications in the perioperative period were light induced tissue damage in four patients and neuropathy in six, requiring prolonged mechanical ventilation in four. Patient and graft survival rates were 85% at 1 year, 69% at 5 years, and 47% at 10 years. Recurrent EPP liver disease occurred in 11 of 17 patients (65%) who survived more than 2 months. Three patients were retransplanted at 1.8, 12.6, and 14.5 years after the initial transplant for recurrent EPP liver disease. In conclusion, the 5‐year patient survival rate in patients transplanted for EPP liver disease is good, but the recurrence of EPP liver disease appears to diminish long term graft and patient survival. (Liver Transpl 2005;11:1590–1596.)

Relationship of Serum α-Fetoprotein to the Severity and Duration of Illness in Patients With Viral Hepatitis

Using a radioimmunoassay which detect concentrations of alpha-fetoprotein as low as 5 ng per ml, 38% of 176 patients with viral hepatitis compared with health volunteers and patients with chronic diseases not affecting the liver. When separated into two groups based on histological classification of liver biopsy specimens, differences in the degree and frequency of increased serum alpha-fetoprotein were related to the severity of the hepatic lesion. Of 75 patients with the lesion of viral subacute hepatic necrosis, in which zones of necrosis bridge adjacent portal triads or central veins, 52% had increased values, and 12% had levels ranging from 500 to 3300 ng per ml. In contrast, only 28% of the 101 patients without bridging necrosis had increased values, and none had levels that exceeded 500 ng per ml. In the patients with subacute hepatic necrosis, comparison of alpha-fetoprotein concentrations with the duration of illness indicated that the protein rose to peak levels in serum as the SGOT was declining. This was confirmed by serial observations in 10 patients. Thus, the increase of alpha-fetoprotein in the sera of patients with severe hepatitis occurs as liver necrosis is subsiding. Due to other known features of alpha-fetoprotein, it is intriguing to speculate that the increase in serum levels of this protein in viral hepatitis reflects hepatic regeneration after parenchymal damage.

Treatment of recurrent allograft dysfunction with intravenous hematin after liver transplantation for erythropoietic protoporphyria

Erythropoietic protoporphyria (EPP) is a rare inherited disorder of the heme biosynthetic pathway in which toxic levels of protoporphyrins often precipitate in the liver, leading to cirrhosis, liver failure, and the need for liver transplantation (OLT). Because the underlying enzyme defect in EPP is bone marrow derived, the risk for recurrent EPP allograft dysfunction is high. Although plasmapheresis may ameliorate acute allograft disease, strategies to maintain disease remission are needed. A 59-year-old man who underwent OLT for hepatic EPP experienced increased bilirubin and aminotransferases on postoperative day 700. Allograft biopsy demonstrated recurrent EPP. He was managed initially with plasmapheresis, hypertransfusion, and infusions of i.v. hematin. After normalization of liver tests, the hematin infusions have been given intermittently, are well tolerated, and associated with normal allograft function for nearly 2 years. This is the first case of the use of hematin given post-OLT to help achieve and maintain remission of allograft EPP disease.

Sequential Liver and Bone Marrow Transplantation for Treatment of Erythropoietic Protoporphyria

Erythropoietic protoporphyria is a disorder of heme synthesis in which deficient ferrochelatase activity leads to excess production and biliary excretion of protoporphyrin. The main clinical features, photosensitivity and hepatobiliary disease that may progress to liver failure, are caused by the toxicity of protoporphyrin. Liver transplantation has been used to treat liver failure in erythropoietic protoporphyria, but excess production of protoporphyrin by the bone marrow continues causing recurrence of liver disease in the majority of patients. This is the first report of successful sequential liver and bone marrow transplantation in a patient with liver failure as a result of erythropoietic protoporphyria. This combination corrected the severe phenotype, resolving the severe photosensitivity and halting erythropoietic protoporphyria associated liver graft injury. Splenectomy seemed to facilitate the successful bone marrow transplant.