Acute intermittent porphyria: clinicopathologic correlation. Report of a case and review of the literature

Acute Intermittent Porphyria: A Review and Rehabilitation Perspective

Acute intermittent porphyria (AIP) is an uncommon metabolic disease that impacts multiple organs and can manifest in many ways. It is often misdiagnosed due to its nonspecific symptoms. Neurovisceral signs and symptoms should alert physicians to consider AIP in the differential after excluding more common causes. Identifying the underlying cause is critical in preventing acute attacks, and trigger avoidance is the optimal approach to managing AIP. Medications that are contraindicated should be reviewed thoroughly. Prompt intravenous hematin administration is the primary treatment for acute attacks, and additional pharmacological therapies may be necessary to treat concurrent symptoms. A severe neurological manifestation of AIP is flaccid paralysis or severe motor weakness, which can develop into total quadriplegia and respiratory insufficiency. A comprehensive rehabilitation program is an integral aspect of the treatment plan. Since the incidence of this disease is low, functional prognosis is not well-known. As a result, it is challenging to determine the most appropriate structure, intensity, and duration of rehabilitation therapy. By extending the treatment plan, individuals with tetraplegia due to AIP can continue to make functional gains years after the onset of weakness. Understanding the disease's functional prognosis will aid in coordinating resources and improving healthcare expenditures.

A Medical Conundrum in a Surgical Setting: Lessons Learned From an Atypical Case of Hyponatremia

In the world of medicine and specifically endocrinology, hyponatremia is one of the commonest electrolyte abnormalities that result in a varied spectrum of presentations. Patients can incur symptoms ranging from lethargy, light-headedness, and confusion to much more severe symptoms such as vomiting, abdominal pain, deterioration in consciousness, and, in critical cases, even seizures. In elderly patients, hyponatremia is a major cause of Delirium and if not treated appropriately, can result in adverse outcomes and complications. In severe cases of hyponatremia, the opinion of an endocrinologist must be sought early for a conscientious investigation of the underlying etiology, as this prevents the need for unnecessary interventions, and thus reduces the risk of potential harm. Despite being a common electrolyte abnormality, hyponatremia can be associated with rare and uncommon etiologies, one of them being acute intermittent porphyria (AIP) as seen in our case. Due to the non-specific presentation of AIP, medical and healthcare professionals must be cautious of this condition, since it can mimic an acute abdomen. Symptoms of AIP usually overlap with other conditions, thus resulting in a diagnostic dilemma. Triggers and factors leading to acute attacks of AIP must be explored and rationalized appropriately, involving a thorough review of a patient's medication and social history. Moreover, discussion in a multidisciplinary team (MDT) setting for such complex presentations has a positive impact on patient care and is therefore recommended.

Acute porphyrias - A neurological perspective

Acute hepatic porphyrias (AHP) can cause severe neurological symptoms involving the central, autonomic, and peripheral nervous system. Due to their relative rarity and their chameleon-like presentation, delayed diagnosis and misdiagnosis are common. AHPs are genetically inherited disorders that result from heme biosynthesis enzyme deficiencies and comprise four forms: acute intermittent porphyria (AIP), variegate porphyria (VP), hereditary coproporphyria (HCP), and ALA-dehydratase porphyria (ALADP). Depending on the clinical presentation, the main differential diagnoses are Guillain-Barré syndrome and autoimmune encephalitis. Red flags that could raise the suspicion of acute porphyria are neurological symptoms starting after severe (abdominal) pain, in association with reddish urine, hyponatremia or photodermatitis, and the presence of encephalopathy and/or axonal neuropathy. We highlight the diagnostic difficulties by presenting three cases from our neurological intensive care unit and give a comprehensive overview about the diagnostic findings in imaging, electrophysiology, and neuropathology.

Syndrome of Inappropriate Antidiuretic Hormone Secretion in a Patient with Uncontrolled Tyrosinaemia Type 1

Syndrome of inappropriate antidiuretic hormone (SIADH) secretion is a recognisable complication of acute porphyria. We report a nine-year-old female patient with hereditary tyrosinaemia type 1 and poor adherence to nitisinone therapy who presented with acute abdominal pain, vomiting and lethargy at Sultan Qaboos University Hospital, Muscat, Oman in 2016. She subsequently developed generalised tonic-clonic seizures attributable to severe hyponatremia that met the diagnostic criteria of SIADH. The acute porphyria screen also appeared positive. The patient responded well to fluid restriction and was discharged home without immediate neurological sequelae. Although acute porphyria is also a recognised complication of uncontrolled tyrosinaemia type 1, to the best of the authors' knowledge, no patient with tyrosinaemia type 1 has been reported to present with SIADH.

Porphyric neuropathy

Acute hepatic porphyrias are inherited metabolic disorders that may present with polyneuropathy, which if not diagnosed early can lead to quadriparesis, respiratory weakness, and death. Porphyric neuropathy is an acute to subacute motor predominant axonal neuropathy with a predilection for the upper extremities and usually preceded by a predominantly parasympathetic autonomic neuropathy. The rapid progression and associated dysautonomia mimic Guillain-Barré syndrome but are distinguished by the absence of cerebrospinal fluid albuminocytologic dissociation, progression beyond 4 wk, and associated abdominal pain. Spot urine test to assess the porphyrin precursors delta-aminolevulinic acid and porphobilinogen can provide a timely diagnosis during an acute attack. Timely treatment with intravenous heme, carbohydrate loading, and avoidance of porphyrinogenic medications can prevent further neurological morbidity and mortality.

Acute intermittent porphyria: focus on possible mechanisms of acute and chronic manifestations

Porphyrias are a group of inherited metabolic diseases that include eight types, each of which is caused by a mutation that affects an enzyme of the heme biosynthetic pathway. When an enzyme defect has physiological significance, it leads to overproduction of pathway precursors prior to the defective step. The partial absence of the third enzyme in the heme biosynthetic pathway, porphobilinogen deaminase (PBGD) also known as hydroxymethylbilane synthase (HMBS), results in acute intermittent porphyria (AIP), which affects mainly women. Subjects who had AIP symptoms were deemed to have manifest AIP (MAIP). Clinical manifestations are usually diverse and non-specific. Acute AIP episodes may present with abdominal pain, nausea, and vomiting, and repeated episodes may result in a series of chronic injuries. Therefore, studying the mechanisms of acute and chronic manifestations of AIP is of great significance. This review aims to summarize the possible mechanisms of acute and chronic manifestations in patients with AIP.

Acute intermittent porphyria presenting with seizures and posterior reversible encephalopathy syndrome: Two case reports and a literature review

INTRODUCTION

Acute intermittent porphyria (AIP) is a rare and challenging hereditary neurovisceral disease with no specific symptoms. Posterior reversible encephalopathy syndrome (PRES) is a clinicoradiological syndrome with bilateral reversible posterior gyriform lesions that can be associated with many different conditions, including AIP. Usually, peripheral neuropathy is considered the most common neurological manifestation of AIP. However, AIP should also be considered when seizures and PRES are associated with unexplained abdominal pain.

CASE PRESENTATION

Both the patients were presented with seizures and PRES on brain magnetic resonance imaging (MRI). Unexplained abdominal pain occurred before the onset of seizures. The AIP diagnosis was made after repeated Watson-Schwartz tests. Hematin was not available for these 2 patients. However, supportive treatment including adequate nutrition and fluid therapy as well as specific antiepileptic drugs aided the patient's recovery and no acute attacks had occurred by the 3-year follow-up.

CONCLUSION

In contrast to other causes of PRES patients, seizure is the most common symptom in AIP patients with PRES. This is a strong diagnostic clue for AIP when ambiguous abdominal pain patients presented with seizures and PRES on brain MRI. A positive prognosis can be achieved with the combination of early recognition, supportive and intravenous hematin therapy, and withdrawal of precipitating factors, including some antiepileptic drugs.

Liver Transplantation for Acute Intermittent Porphyria: Biochemical and Pathologic Studies of the Explanted Liver

Acute intermittent porphyria (AIP) is an autosomal-dominant hepatic disorder caused by the half-normal activity of hydroxymethylbilane (HMB) synthase. Symptomatic individuals experience life-threatening acute neurovisceral attacks that are precipitated by factors that induce the hepatic expression of 5-aminolevulinic acid synthase 1 (ALAS1), resulting in the marked accumulation of the putative neurotoxic porphyrin precursors 5-aminolevulinic acid (ALA) and porphobilinogen (PBG). Here, we provide the first detailed description of the biochemical and pathologic alterations in the explanted liver of an AIP patient who underwent orthotopic liver transplantation (OLT) due to untreatable and debilitating chronic attacks. After OLT, the recipient's plasma and urinary ALA and PBG rapidly normalized, and her attacks immediately stopped. In the explanted liver, (a) ALAS1 mRNA and activity were elevated approximately ~3- and 5-fold, and ALA and PBG concentrations were increased ~3- and 1,760-fold, respectively; (b) uroporphyrin III concentration was elevated; (c) microsomal heme content was sufficient, and representative cytochrome P450 activities were essentially normal; (d) HMB synthase activity was approximately half-normal (~42%); (e) iron concentration was slightly elevated; and (f) heme oxygenase I mRNA was increased approximately three-fold. Notable pathologic findings included nodular regenerative hyperplasia, previously not reported in AIP livers, and minimal iron deposition, despite the large number of hemin infusions received before OLT. These findings suggest that the neurovisceral symptoms of AIP are not associated with generalized hepatic heme deficiency and support the neurotoxicity of ALA and/or PBG. Additionally, they indicate that substrate inhibition of hepatic HMB synthase activity by PBG is not a pathogenic mechanism in acute attacks.

Novel A219P mutation of hydroxymethylbilane synthase identified in a Chinese woman with acute intermittent porphyria and syndrome of inappropriate antidiuretic hormone

Acute intermittent porphyria (AIP) is an autosomal dominant metabolic disorder caused by deficiency of the heme biosynthetic enzyme hydroxymethylbilane synthase (approved gene symbol HMBS), also known as porphobilinogen deaminase (PBGD). AIP is characterised by intermittent attacks of abdominal pain, vomiting, and neurological complaints. The highly variable symptomatic presentation of AIP causes confusion with other diseases and results in a high misdiagnosis rate (68% in China) and delayed effective treatments. Based on biochemical and genetic analysis of two Chinese families, a new and a previously reported HMBS mutation were identified in patients with AIP and syndrome of inappropriate antidiuretic hormone (SIADH). The novel HMBS mutation is the 655G>C point mutation (A219P). In addition, the 973C>T point mutation (R325X), which had been previously reported in two Danish families, was identified.

Acute intermittent porphyria: a diagnostic challenge

Acute intermittent porphyria is a metabolic disorder rarely seen in prepubertal children. A delay in diagnosis of acute intermittent porphyria is common because of variable and nonspecific symptoms. We report an 8-year-old boy with right hemimegalencephaly and intractable seizures, who presented with dark-colored urine, hypertension, increasing lethargy, fluctuating seizures, and poor oral intake. He subsequently developed hyponatremia secondary to syndrome of inappropriate antidiuretic hormone secretion. His urinalysis was negative for red blood cells, and a random urine porphobilinogen level was elevated. Further biochemical and molecular testing confirmed the diagnosis of acute intermittent porphyria. His antiepileptic medications were discontinued and hemin administered, with dramatic clinical improvement. The diagnosis of acute intermittent porphyria was challenging because of his underlying neurologic condition. This case highlights the variable presentation of acute intermittent porphyria and emphasizes the importance of considering the diagnosis even in young patients with underlying neurologic conditions when they present with nonspecific neurovisceral symptoms or with unexplained neurologic deterioration.

Intensive care management of patients with acute intermittent porphyria: Clinical report of four cases and review of literature

Acute intermittent porphyria (AIP), the most common and the most severe form of acute hepatic porphyria, is an autosomal dominant condition. It results from lower-than-normal levels (less than 50%) of porphobilinogen (PBG) deaminase. Patients may present commonly with gastrointestinal complaints and neuropsychiatric manifestations. Diagnosis may be confirmed with the presence of intermediary metabolites of haem synthesis, amino levulinic acid (ALA) and PBG in urine or with specific enzyme assays. Abdominal pain is the most common symptom (90%). Peripheral polyneuropathy, primarily motor with flaccid paresis of proximal musculature, with or without autonomic involvement, is characteristic. Respiratory failure necessitates ventilator and intensive care support. Avoidance of precipitating factors and the use of haem preparations and intravenous dextrose form the basis of management. Gabapentin and propofol, rather than the conventional antiepileptics appear to be the appropriate choice for seizure control. Here, we present intensive care management of four cases of AIP with varying clinical presentation.

Painful peripheral neuropathies

Peripheral neuropathies are a heterogeneous group of diseases affecting peripheral nerves. The causes are multiple: hereditary, metabolic, infectious, inflammatory, toxic, traumatic. The temporal profile includes acute, subacute and chronic conditions. The majority of peripheral neuropathies cause mainly muscle weakness and sensory loss, positive sensory symptoms and sometimes pain. When pain is present, however, it is usually extremely intense and among the most disabling symptoms for the patients. In addition, the neurological origin of the pain is often missed and patients receive inadequate or delayed specific treatment. Independently of the disease causing the peripheral nerve injury, pain originating from axonal pathology or ganglionopathy privileges neuropathies affecting smaller fibres, a clinical observation that points towards abnormal activity within nociceptive afferents as a main generator of pain. Natural activation of blood vessels or perineurial nociceptive network by pathology also causes intense pain. Pain of this kind, i.e. nerve trunk pain, is among the heralding symptoms of inflammatory or ischemic mononeuropathy and for its intensity represents itself a medical emergency. Neuropathic pain quality rekindles the psychophysical experience of peripheral nerves intraneural microstimulation i.e. a combination of large and small fibres sensation temporally distorted compared to physiological perception evoked by natural stimuli. Pins and needles, burning, cramping mixed with numbness, and tingling are the wording most used by patients. Nociceptive pain instead is most often described as aching, deep and dull. Good command of peripheral nerve anatomy and pathophysiology allows timely recognition of the different pain components and targeted treatment, selected according to intensity, type and temporal profile of the pain.

Reversible MRI findings of porphyric encephalopathy. A report of two cases

We describe the magnetic resonance imaging (MRI) findings in two patients admitted to our institution with neuropsychiatric symptoms and severe abdominal pain diagnosed as acute intermittent porphyria (AIP). MRI revealed multiple lesions which regressed following treatment. We suggest reversible cerebral vasospasm underlies the MRI abnormalities and the cerebral symptoms in porphyria.

Effect of the heme oxygenase inducer hemin on blood haemostasis measured by high-frequency ultrasound

1. Heme compounds, like hemin, a heme oxygenase-1 inducer, are used in the treatment of acute porphyria treatment. The side-effects of hemin on haemostasis have been reported. To address those effects, in the present study we used a sensitive, high-frequency ultrasound technique to record acoustic velocity and to investigate whole blood clotting in Wistar rats treated chronically with hemin (50 mg/kg per day). 2. The hemin-induced disturbances in haemostasis measured were comparable to the heparin reference treatment, with a significant decrease in clotting velocity in both groups compared with controls (e.g. the time to clot was 40 +/- 5, 53 +/- 13 and 10 +/- 2 min, respectively; P < 0.05). Precautions must be taken when using high doses of hemin or in the treatment of bleeding diseases. 3. Further investigations are required to explore the effects of hemin in thrombosis models, because it could be a promising 'old drug' for the treatment of venous thrombosis in patients.

Acute intermittent porphyria with peripheral neuropathy complicated by small-fiber neuropathy

We describe a 60-year-old male patient with acute intermittent porphyria (AIP) who presented with initial abdominal pain and subsequent quadriplegia and respiratory failure. Small fiber neuropathy was demonstrated by measuring intra-epidermal nerve fiber density (IENFD) using protein gene product 9.5 (PGP 9.5) immunostaining on three consecutive skin punch biopsies of the distal lower limb. The biopsy findings demonstrated some correlation with progression of the patient's clinical condition. Neuropathy in AIP can have a small-fiber component rather than being solely a large-fiber neuropathy.

Syndrome of Inappropriate Antidiuretic Hormone Secretion Associated with Coproporphyria: Case Report and Review of Literature

OBJECTIVE

To remind physicians to consider the hepatic porphyrias in the differential diagnosis of the syndrome of inappropriate antidiuretic hormone secretion.

METHODS

We present a case report of a patient seen in the hospital for severe hyponatremia, who was discovered to have the syndrome of inappropriate antidiuretic hormone secretion attributable to coproporphyria. Results of laboratory tests of the patient and her family are presented.

RESULTS

A 54-year-old woman was seen in the hospital because of severe hyponatremia accompanied by generalized seizures. Her serum sodium concentration was 112 mEq/L, with concomitant serum and urine osmolalities of 235 and 639 mOsm/kg, respectively. Renal, thyroid, and adrenal functions were normal. Brain, chest, abdominal, and pelvic imaging studies were negative for occult malignant disease. Urinary excretions of porphobilinogen and aminolevulinic acid were substantially elevated. Results of follow-up urine, plasma, and fecal porphyrin studies were consistent with coproporphyria. Results of porphyrin metabolic studies of the patient's family showed normal findings in her parents and a minimally increased fecal coproporphyrin concentration and urinary uroporphyrin excretion in her sister.

CONCLUSION

An endocrinology consultation is often requested for patients with hyponatremia. It is important to consider the acute hepatic porphyrias in the differential diagnosis, even though these are rare disorders and the family history may not always be helpful because of the high frequency of asymptomatic carriers.

Peripheral neuropathy in chronic occupational inorganic lead exposure: a clinical and electrophysiological study

BACKGROUND AND OBJECTIVES

Traditionally the neuromuscular disorder associated with lead poisoning has been purely motor. This study assessed peripheral nerve function clinically and electrophysiologically in 46 patients with neuropathic features out of a total population of 151 workers with raised blood and/or urinary lead concentrations.

RESULTS

Average duration of occupational exposure for the neuropathic group ranged from 8-47 years (mean 21.7). Their mean blood lead concentration (SD) was 63.9 (18.3) microg/dl (normal <40), urinary lead 8.6 (3.3) microg/dl (normal<5.0), urinary coproporphyrins 66.7 (38.4) microg/g creatinine (20-80), urinary aminolaevulinic acid 1.54 (0.39) mg/g creatinine (0.5-2.5). All 46 had distal paraesthesiae, pain, impaired pin prick sensation, diminished or absent ankle jerks, and autonomic vasomotor or sudomotor disturbances. Reduced vibration sensation and postural hypotension were present in all 20 studied. None of these 46 patients had motor abnormalities. Motor conduction velocity and compound muscle action potential amplitudes were normal, with marginally prolonged distal motor latencies. Sensory nerve action potential amplitudes lay at the lower end of the normal range, and the distal sensory latencies were prolonged. No direct correlation was found between the biochemical variables, and the clinical or electrophysiological data.

CONCLUSIONS

One additional patient was seen with shorter term exposure to lead fumes with subacute development of colicky abdominal pain, severe limb weakness, and only minor sensory symptoms. Unlike the patients chronically exposed to lead, he had massively raised porphyrins (aminolaevulinic acid 21 mg/g creatinine, coproporphyrins 2102 microg/g creatinine). Patients with unusually long term inorganic lead exposure showed mild sensory and autonomic neuropathic features rather than the motor neuropathy classically attributed to lead toxicity. It is proposed that the traditional motor syndrome associated with subacute lead poisoning is more likely to be a form of lead induced porphyria rather than a direct neurotoxic effect of lead.

The acute porphyrias

The various types of acute porphyria are discussed, as well as their mode of inheritance and the enzyme deficiencies responsible for the symptoms. The symptoms and signs of an acute attack are then described, especially those due to neuropathies and to disturbances of behaviour. Agents which can precipitate attacks are listed. These are most frequently drugs, and as they include those used for anti-epileptic treatment problems soon arise as seizures often occur in this condition. The main complications are hypertension and renal failure, and examples of hyponatraemia and folate deficiency are illustrated. The urgency to diagnose this disorder lies in the need to avoid precipitating factors. Screening tests are discussed, and those needed to confirm the diagnosis. The prognosis has improved over the years, due to increased awareness of the disorder, and better management. During an acute attack the treatment of pain and vomiting will be of particular importance, and then haematin or chelating agents can be tried. With better management most of those who have inherited acute porphyria should be able to lead a normal life.

Treatment of seizures in acute intermittent porphyria: safety and efficacy of gabapentin

Treatment of seizures in acute intermittent porphyria represents a therapeutic dilemma. Patients needing chronic therapy often experience acute porphyric attacks due to increased hepatic metabolism induced by the antiepileptic drugs themselves. Gabapentin is a new antiepileptic drug not appreciably metabolized by the liver in humans, and it appears to be safe and effective in the maintenance therapy of epilepsy in these patients. We report a patient affected by partial and generalized seizures in the course of acute intermittent porphyria, who was safely and successfully treated with gabapentin.