Porphyria refers to a group of rare genetic disorders that result from abnormalities in the heme biosynthesis pathway, leading to the accumulation of porphyrins or porphyrin precursors in the body. Heme is an essential component of hemoglobin, which carries oxygen in red blood cells.
Porphyria is caused due to disturbances in the metabolic pathways such as heme biosynthetic pathway. The organ affected by this disorder is purely dependent on the enzyme that is responsible for a certain biosynthetic pathway related to the organ. Abnormal forms of porphyrins are released which lead to various clinical manifestations. In many cases porphyria is inherited since it is associated with eight predominant forms of faulty genes which are responsible for neurological or cutaneous diseases.
Types of Porphyria
Porphyria is classified as acute and non-acute forms depending on its organ involvement and pathways affected. Acute Porphyria is more severe and involves neuromuscular discomfort, abdominal pain and also psychiatric complications. Porphyria is often difficult to diagnose because of its neurovisceral involvement which causes symptoms that appear in many other medical conditions. ALA dehydratase deficiency porphyria (ADP): The deficient enzyme that is found in this kind of disorder is the delta amino levulinic acid dehydratase. It is acquired as an autosomal recessive condition. ADP is very rare. Photosensitivity is one of the predominant factors associated. However, this symptom is usually followed by neuro visceral involvement.
Acute Intermittent Porphyria: This acute form of porphyria is caused by porphobilinogen deaminase and it is one of the most common forms of porphyria. It is predominant in females especially during puberty and post menopause. The clinical manifestations include excess urinary formation followed by excretion of precursors associated with porphyrin formation such as ALA and PBG.
Variegate Porphyria: It is caused by the deficiency of protoporphyrinogen oxidase. Most clinical manifestations pertaining to this acute form of porphyria is associated with cutaneous involvement leading to skin lesions.
: It is caused due to the deficiency of the enzyme coproporphyrinogen oxidase. This form of porphyria is predominantly seen in hepatobilliary disease.
: Acute porphyrias include acute intermittent porphyria (AIP), hereditary coproporphyria (HCP), variegate porphyria (VP), and ALA dehydratase deficiency porphyria (ADP). These types primarily affect the nervous system and can cause acute attacks with symptoms such as severe abdominal pain, nausea, vomiting, constipation, muscle weakness, and neurological manifestations like peripheral neuropathy, seizures, and psychiatric disturbances. These attacks can be triggered by certain drugs, hormones, fasting, alcohol, and stress.
: Cutaneous porphyrias include porphyria cutanea tarda (PCT), erythropoietic protoporphyria (EPP), congenital erythropoietic porphyria (CEP), and hepatoerythropoietic porphyria (HEP). Cutaneous porphyrias primarily affect the skin and may cause photosensitivity, blistering, skin fragility, and hyperpigmentation upon sun exposure. PCT is the most common type and is associated with liver dysfunction, iron overload, and hepatitis C infection.
Symptoms of Acute porphyria
Acute forms of porphyria are often fatal if ignored. Symptoms are severe abdominal pains, vomiting and nausea. In case of patients with a history of hypertension, cardiovascular problems might lead to instant death. Other key signs include muscular dystrophy, weakness, radiating pain in the back and extremities. Porphyria has close associations with many psychiatric conditions such as confusion, hallucination, paranoia and disoriented behavior.
Management and treatment of porphyria
Diagnosis of porphyria involves a combination of clinical evaluation, biochemical testing, and genetic analysis. Urinary and/or plasma levels of porphyrins, porphobilinogen, and delta-aminolevulinic acid (ALA) are measured to identify specific porphyria types. Genetic testing can confirm the specific genetic mutation causing the disorder.
Treatment of porphyria aims to manage symptoms, prevent attacks, and minimize complications. This may involve avoiding triggers such as certain medications and substances, maintaining a healthy diet, and managing pain and neurological symptoms. In some cases, intravenous heme therapy may be used to reduce porphyrin buildup and alleviate symptoms during acute attacks.
Overall, porphyria is a complex group of disorders requiring a multidisciplinary approach involving hematologists, geneticists, and dermatologists to diagnose, manage, and provide long-term care to affected individuals. Genetic counseling is also crucial for affected individuals and their families due to the hereditary nature of the disorder.
The effective management of porphyria is often associated with the accuracy of diagnosis. This can be attained by the measurement of PBG in the urine. Care must be taken while collecting the specimen as the PBG when exposed for a long time to light can lead to the formation of dark red form of because of porphobilin.
Haem arginate administration has to be done carefully through a central line or through a large vein as it is an irritant to the vein. Post infusion, the vein is flushed with sodium chloride. Vein positions have to be changed on alternate days to avoid perivenous inflammations. Appropriate amount of calories have to be given to patients as malnutrition can aggravate the porphyria attacks. Cardiac patients have to be given beta-blockers to prevent tachycardia. Bacterial or viral infections have to be treated prior to the treatment with haem arginate.
Wood's Lamp Examination
A wood's lamp examination helps the doctor confirm a fungal infection or bacterial infection. The doctor is able to determine the cause of any light or dark colored spot on the skin using this examination. This is a test using Ultraviolet or UV light to look more closely at the skin.
In case of fair skinned individuals, Wood's lamp can detect Vitiligo or any other depigmentation even when it is not visible to the eye under normal conditions. In case of detection, Vitiligo can be treated at an early stage even before it is visible to the normal eye, thereby minimizing treatment and preventing further expansion of the disorder.
What is Wood's lamp?
Also known as Black Light Test, or Ultraviolet Light Test, this is based on the use of ultraviolet light which is shined on the area being examined, when performed in a dark room. It emits ultraviolet light in the 365 nanometer range and when the light is shined directly on the area in darkness, the dermatologist looks for any change in color or fluorescence. While normal skin does not fluoresce under the light of the Wood's lamp, affected skin 'glows' in dark. if any fungal or bacterial infection or pigment is present, the Wood's lamp can strengthen or lessen the suspicion of a particular diagnosis based on the color of florescence of the affected skin being illuminated. Even subtle color changes can be detected very well using Wood's lamp.
You will be seated in a dark room usually in the dermatologist's office. The doctor turns on the Wood's lamp and holds it approximately 5 inches from the skin to look for color changes. It will reveal skin color changes not visible to the mere eye examination. The patient is advised not to look directly into the light when being examined. This portion of the examination usually lasts for less than a minute and the patient feels no discomfort from the examination.
Pre and post procedure
Before the Wood's lamp examination do not wash the area or apply any cream to the skin to avoid inaccurate results. Following the procedure, the dermatologist may decide to treat the skin condition based on the results of the Wood's lamp examination. Additional tests are sometimes done to arrive at the correct diagnosis. No aftercare is recommended specific to the examination and depending on the result of the examination the physician may recommend treatment of a skin disorder.
Why is Wood's lamp examination done?
Certain skin problems including bacterial and fungal infections, Porphyria, skin coloring changes in Vitiligo, head lice and nits, Erythrasma and other pigmentary disorders can be performed using this test.
The test also reveals different colors according to the type of the skin disease which includes:
Exposure to Ultra violet Light for prolonged duration can result in skin damage and cancer of the skin. But this test hardly lasts for a minute and the intensity of the light is minimal. Patients should avoid looking directly into the UV light and since the time for the procedure is very minimal - less than a minute - the procedure is well tolerated as there is no associated pain and no side effects as a result. Beware that the presence of other materials like certain kind of makeup, deodorants, perfume, body lotion or soap can also fluoresce leading to difficulty in arriving at a conclusive diagnosis. Equally if the room is not dark enough, it may present difficulty for proper examination. Not all bacteria or fungi show up under the UV light.
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Bibliography / Reference
Collection of Pages - Last revised Date: March 5, 2024