(P) Lec 3: Porphyrins (Part 2) Flashcards
- These are metabolic intermediates in the hemoglobin, myoglobin, and cytochrome synthesis
- It produces a red-violet to red-brown color
- These will not increase unless there is a problem with heme synthesis
Porphyrins
This molecule is composed of heme and globin
Hemoglobin
- This molecule is composed of iron and a protoporphyrin ring
- This also incorporates into a protein (globin) to produce a biologically functional hemoprotein (hemoglobin)
Heme
Three Clinically Significant Forms of Porphyrins
- Found in urine and is most stable in water
- Found in urine, stool, and blood
- Found in stool
- Uroporphyrin
- Coproporphyrin
- Protoporphyrin
The three forms of porphyrins (Uroporphyrin, Coproporphyrin, Protoporphyrin) are found within the biological ____ produced by the body
Fluids
Note: Increased levels in body fluids indicate abnormal heme synthesis
- Most porphyrins in the body are present in this form
- This is a functional form of the compound that must be used in heme synthesis
- Are believed to be colorless, unstable, and do not fluoresce
Porphyrinogens
- Initially, porphyrins are in the form of ____
- It will be converted to porphyrins for heme synthesis when they are ____ in the body
- Porphyrinogens
- Oxidized
In cases wherein a sample contains porphyrinogens upon excretion, when they are exposed to ____, the porphyrinogens will be converted to porphyrin
Air
Pathway of Heme Synthesis
- The ____ and ____ are the main sites of heme synthesis
- The conversion of one product to another through enzymatic action happens ____ the cell
- Reduced enzymatic activity results in excess production of one or more ____ substances
- Liver and Bone Marrow
- Inside
- Precursor
Pathway of Heme Synthesis
- ____ and ____ are present in the mitochondria and will serve as raw materials for heme synthesis
- The 2 raw materials will be acted upon by ____ to produce ____
- Glycine and Succinyl-CoA
- ALA synthase; δ-aminolevulinic acid (ALA)
Pathway of Heme Synthesis
- As δ-aminolevulinic acid (ALA) is produced, it will be acted upon by ____ therefore producing ____
- ____ molecules of ALA will produce ____ molecules of the new product
- ALA dehydratase; Porphobilinogen (PBG)
- (2) for ALA and (4) for PBG
Pathway of Heme Synthesis
- The PBG will be acted upon by ____ to produce ____ which is a linear tetrapyrrole
- The new product will now be the substrate of ____ in producing ____
- Uroporphyrinogen-I Synthase; Hydroxymethylbilane
- Uroporphyrinogen-III Co-Synthase; Uroporphyrinogen-III
Note: Uroporphyrinogen-I Synthase is aka Hydroxymethylbilane Synthase
Pathway of Heme Synthesis
- Hydroxymethylbilane will be spontaneously acted upon by a specific enzyme to produce ____
- As Uropophyrinogen-III is being produced, it will be acted upon by ____ to produce ____
- Uroporphyrinogen-I
- Uroporphyrinogen carboxylase; Coproporphyrinogen-III
Pathway of Heme Synthesis
- As Coproporphyrinogen-III is produced, it will be acted upon by ____ to produce ____
- The new product will then by acted upon by ____ to produce ____
- Coproporphyrinogen oxidase; Protoporphyrinogen-III
- Protoporphyrinogen oxidase; Protoporphyrin III
Note: Protoporphyrin III is aka Protoporphyrin IX
Pathway of Heme Synthesis
The Protoporphyrin ring IX will be acted upon by ____ producing your heme
Ferrochelatase (heme synthase)
Pathway of Heme Synthesis
Heme, protoporphyrin IX, protoporphyrinogen IX, and the conversion of glycine + succinyl-CoA to delta aminolevulinic acid happens where?
In the mitochondria (because the process needs energy)
Pathway of Heme Synthesis
The conversion that happens from delta-aminolevulinic acid to coproporphyrinogen happens where?
Cytoplasm (it needs less energy than those processes that occur in the mitochondria)
In the heme synthesis pathway, it can also relate to ____ because this targets heme synthesis, specifically ALA dehydratase and ferrochelatase
Lead poisoning/ Presence of Lead
A deficiency of one enzyme involved in the heme synthesis pathway will lead to porphyria EXCEPT for what enzyme?
ALA Synthase
If the deficiency of ALA Synthase does not lead to porphyria, what does it result to?
Sideroblastic Anemia
- Refers to conditions wherein there is an aberration or disturbance in heme synthesis leading to the accumulation of porphyrins
- A group of rare, inherited, or acquired metabolic disorders caused by a loss or gain of function and a mutation in the enzymes responsible for heme biosynthesis
Porphyria
Types of Porphyria
Refers to the overproduction of heme precursors in the 1.) liver and 2.) bone marrow
- Hepatoerythropoietic Porphyria (HEP)
- Erythropoietic Porphyria (EP)
Types of Porphyria
These 2 types are the only acquired ones while the rest are all inherited
- Plumboporphyria (PP)
- Porphyria Cutanea Tarda (PCT)
The ending of all these types of porphyrias is that there is always an overproduction, accumulation, and excretion of toxic ____ compounds and porphyrins
Precursor
Symptoms of Porphyria
- Manifestations include abdominal pain, vomiting, constipation, tachycardia, hypertension, etc.
- Plumboporphyria (PP) and Acute Intermittent Porphyria (AIP) present with this type of symptom
Neurologic/Neuropsychiatric
Symptoms of Porphyria
- Manifestations include photosensitivity (most usual presenting symptom), blisters, facial hair, and hyperpigmentation
- Congenital Erythropoietic Porphyria (CEP), Porphyria Cutanea Tarda (PCT), Hepatoerythropoietic Porphyria (HEP), and Erythropoietic Porphyria (EP) present with this type of symptom
Cutaneous
Symptoms of Porphyria
- Includes both neurologic/neuropsychiatric and cutaneous manifestations
- Hereditary Coproporphyria (HCP) and Variegate Protoporphyria (VP) present with this type of symptom
Neurocutaneous
Symptoms of Porphyria
Give the porphyrias associated with this symptom: Neurologic/ Neuropsychiatric
- Plumboporphyria (PP)
- Acute Intermittent Porphyria (AIP)
Symptoms of Porphyria
Give the porphyrias associated with this symptom: Cutaneous
- Congenital Erythropoietic Porphyria (CEP)
- Porphyria Cutanea Tarda (PCT)
- Hepatoerythropoietic Porphyria (HEP)
- Erythropoietic Porphyria (EP)
Symptoms of Porphyria
Give the porphyrias associated with this symptom: Neurocutaneous
- Hereditary Coproporphyria (HCP)
- Variegate Protoporphyria (VP)
Types of Porphyria
There is increased aminolevulinic acid (ALA) and porphobilinogen (PBG) in urine producing a black or red color but turns dark brown upon exposure to air or light
- Plumboporphyria (PP)
- Acute Intermittent Porphyria (AIP)
Note: The porphyrias that present with neurologic symptoms
Types of Porphyria
In Plumboporphyria (PP) and Acute Intermittent Porphyria (AIP), what 2 substances give the characteristic red and black color of urine respectively?
- Red: Porphyrin
- Black: Porphobilin
Types of Porphyria
- Is aka ALA-dehydratase (ALAD) deficiency porphyria
- Lead and ferrochelatase are inhibitors to ALAD
- There is increased urine aminolevulinic acid (ALA) but with normal excretion of porphobilinogen (PBG)
Plumboporphyria (PB)
Types of Porphyria
- Dithiothreitol or sulfhydryl reagent is used to differentiate this type with lead poisoning
- It is sometimes mistaken for lead poisoning due to a similar presentation of increased ALA
Plumboporphyria (PB)
Types of Porphyria
In Plumboporphyria (PB) testing, if you add the dithiothreitol or sulfhydryl reagent and the ALA increases, what does it mean?
(+) for Plumboporphyria (PB)
Types of Porphyria
In Plumboporphyria (PB) testing, if the ALA in urine is increased at first but then turns normal upon the addition of the dithiothreitol or sulfhydryl reagent, what does it mean?
(+) for Lead Poisoning
Types of Porphyria
The enzyme deficient in this condition is the porphobilinogen deaminase or hydroxymethylbilane synthase/uroporphyrinogen-I-synthase
Acute Intermittent Porphyria (AIP)
Types of Porphyria
- The rarest among all porphyrias and is also the most severe
- The enzyme deficient is Uroporphyrinogen III cosynthase (Gunther’s disease)
Congenital Erythropoietic Porphyria (CEP)
Types of Porphyria
- There is an increase of uroporphyrin and coproporphyrin in urine and stool
- The teeth fluoresce red (erythrodontia) under UV light due to the deposition of porphyrin in the dentin
- Manifestations are seen as early in infants
- Infants produce red to brown urine and exhibit cutaneous photosensitivity (usual symptom)
Congenital Erythropoietic Porphyria (CEP)
Types of Porphyria
- The enzyme deficient is Uroporphyrinogen decarboxylase
- The most common porphyria
- Manifested by having blisters and fragility in light-exposed skin due to free radicals present in the skin leading to oxidative damage
Porphyria Cutanea Tarda (PCT)
Types of Porphyria
- Liver damage is also possible because of iron depletion
- There is abnormal growth of hair present
- There’s increased isocoproporphyrin and uroporphyrin in the patient’s biologic fluids
Porphyria Cutanea Tarda (PCT)
Types of Porphyria
Types of Porphyria Cutanea Tarda (PCT):
1. Deficiency of the enzyme is restricted to liver
2. Deficiency of the enzyme is present in all tissues
- Type 1 PCT
- Type 2 PCT
Types of Porphyria
- The enzyme that is deficient is Uroporphyrinogen decarboxylase (reduced activity of 90% and more)
- Affects both the liver and bone marrow
- Photosensitivity begins in childhood
Hepatoerythropoietic Porphyria (HEP)
Types of Porphyria
- Hepatic diseases are common and present later on
- There is presence of abnormal/excess facial hair and scarring (blisters) of the hands and face
- There is increased isocoproporphyrin, uroporphyrin, and zinc protoporphyrin (ZPP)
Hepatoerythropoietic Porphyria (HEP)
Types of Porphyria
- The enzyme deficient is ferrochelatase
- It is the second most common porphyria
- Manifested as burning of light-exposed skin
Erythropoietic Porphyria (EP)
Types of Porphyria
- There is increased free erythrocyte protoporphyrin (FEP) and Zn protoporphyrin in RBC, plasma, and stool because iron is not incorporated in the RBC
- Symptoms include photosensitivity, burning, itching, pain in the skin, excessive hair growth, and liver disease
Erythropoietic Porphyria (EP)
Types of Porphyria
- The enzyme deficient is coproporphyrinogen oxidase
- The hallmark is increased coproporphyrin in stool (sometimes in urine)
- There is increased ALA and PBG
- Harderoporphyria is a rare erythropoietic form of it
Hereditary Coproporphyria (HCP)
Types of Porphyria
- Aka South African porphyria
- The enzyme deficient is protoporphyrinogen oxidase
- Its manifestations are the same with Acute Intermittent Porphyria (AIP)
- The hallmark is increased protoporphyrin and coproporphyrin in stool
Variegate Protoporphyria (VP)
Types of Porphyria
- These are aka porphyrinurias wherein there is an increased excretion of urinary porphyrins
- It is not a defect in the biochemical synthesis of heme but a result of conditions such as toxins and drugs
Secondary Porphyrias
Types of Porphyria
Regular or Secondary porphyrias?
1. Increased ALA and porphobilinogen in urine and other body fluids
2. Increased ALA but with normal porphobilinogen in urine
- Regular porphyria
- Secondary porphyria
Treatment
If a patient suffers from porphyria of the cutaneous type, they should avoid what?
Sunlight
Treatment
This can be given for a hematin limit synthesis of porphyrins in the cells of the bone marrow
Hematin
Treatment
Decrease the heme load by having therapeutic ____ or giving ____ to chelate the iron present
- Phlebotomy
- Deferoxamine
Laboratory Determination
What 2 qualitative screening tests can be used to measure porphobilinogen (PBG) and ALA?
- Watson-Schwartz
- Hoesch Test
Laboratory Determination
In order to measure PBG and ALA quantitatively, what test can be performed?
Ion Exchange Column
Laboratory Determination
Between the Watson-Schwartz and Hoesch Test, what is the confirmatory test for the other one?
Hoesch Test (it confirms the result of Watson-Schwartz)
Laboratory Determination
- Porphobilinogen (PBG) forms a ____ color when mixed with ____
- It is a qualitative ____ test for the detection and differentiation of ____ and porphobilinogen
- A positive result for PBG and ALA in urine is indicated by a ____ color
- Red-orange; Ehrlich’s reagent (pdab)
- Screening; urobilinogen
- Red-orange
Note: pdab means para-dimethylaminobenzaldehyde
Laboratory Determination
- An extraction method is done
- Urine is added with Ehrlich’s reagent alongside sodium acetate
- If the tube turns red or pink, it is (+) for either urobilinogen or porphobilinogen
- Add chloroform to determine whether urobilinogen or porphobilinogen is present
- There will be a production of 2 layers afterwards
Watson-Schwartz
Laboratory Determination
In Watson-Schwartz, what do you add to differentiate urobilinogen from porphobilinogen that forms 2 layers?
Chloroform OR Butanol
Laboratory Determination
In Watson-Schwartz, the Ehrlich’s reagent is added alongside what other substance to produce a red/pink color?
Sodium Acetate
Laboratory Determination
Watson-Schwartz:
- The top layer is aqueous and the red/pink chloroform settled at the bottom
- After adding butanol, the red/pink color is present at the top
Urobilinogen
Note: Butanol can be used if chloroform is not present
Laboratory Determination
Watson-Schwartz:
- The bottom layer is aqueous and the red/pink chloroform settled at the top
- After adding butanol, the red/pink color is present at the bottom
Note: Butanol can be used if chloroform is not present
Porphobilinogen
Laboratory Determination
What interfering agents sometimes act up when performing Watson-Schwartz?
Urobilinogen and Indole
Laboratory Determination
The reagent used for this test does not react with urobilinogen as this is only used to confirm the result of the other test
Hoesch Test
Laboratory Determination
What specimens (3) can be used?
- 24H urine
- Whole blood
- 1g of fecal sample
Note: The 3 sources of porphyrins are urine, blood, and stool
Laboratory Determination
What is the anticoagulant of choice?
EDTA
Specimen Considerations
- Porphyrin is ____ sensitive, together with bilirubin
- Store the specimen at ____ degrees Celsius for ____ hours
- If not performing ASAP, store the specimen at ____ degrees Celsius
- Light
- 4 degrees for 48H
- 23 degrees
Methods
- The ____ and ____ lamps are used for qualitative screening methods
- Porphyrins ____ under UV light
- ____ colored fluorescence indicates a (+) result
- UV and Wood’s
- Fluoresce
- Orange-red
Methods
- Other qualitative tests include: ____ , ____ , and ____
- An excitation wavelength is set at ____ to ____ nm
- An emission wavelength is set at ____ to ____ nm
- Fluorometry, HPLC, and HP-TLC
- 400 to 405nm
- 594 to 598nm
Identify the type of porphyria
ALA-D deficiency
Plumboporphyria (PB)
Identify the type of porphyria
Increased urine ALA but with the normal porphobilinogen (PBG) excretion
Plumboporphyria (PB)
Identify the type of porphyria
Dithiothreitol or sulfhydryl reagent
Plumboporphyria (PB)
Identify the type of porphyria
Porphobilinogen deaminase or Hydroxymethylbilane synthase (uroporphyrinogen-I-synthase) is deficient
Acute Intermittent Porphyria (AIP)
Identify the type of porphyria
Uroporphyrinogen III cosynthase is deficient
Congenital Erythropoietic Porphyria (CEP)
Identify the type of porphyria
Gunther’s Disease
Congenital Erythropoietic Porphyria (CEP)
Identify the type of porphyria
There is increased uroporphyrin and coproporphyrin in urine and stool
Congenital Erythropoietic Porphyria (CEP)
Identify the type of porphyria
There is increased coproporphyrin in urine and stool
- Congenital Erythropoietic Porphyria (CEP)
- Hereditary Coproporphyria (HCP)
- Variegate Protoporphyria (VP)
Identify the type of porphyria
There is photosensitivity
- Congenital Erythropoietic Porphyria (CEP)
- Porphyria Cutanea Tarda (PCT)
- Hepatoerythropoietic Porphyria (HEP)
- Erythropoietic Porphyria (EP)
Identify the type of porphyria
Uroporphyrinogen decarboxylase is deficient
- Porphyria Cutanea Tarda (PCT)
- Hepatoerythropoietic Pophyria (HEP)
Identify the type of porphyria
Liver damage/disease
- Porphyria Cutanea Tarda (PCT)
- Hepatoerythropoietic Porphyria (HEP)
- Erythropoietic Porphyria (EP)
Identify the type of porphyria
Increased isocoproporphyrin, uroporphyrin, and zinc protoporphyrin (ZPP)
Hepatoerythropoietic Porphyria (HEP)
Identify the type of porphyria
Ferrochelatase is deficient
Erythropoietic Porphyria (EP)
Identify the type of porphyria
There is increased free erythrocyte protoporphyrin (FEP) and Zn protoporphyrin in RBC, plasma, and stool
Erythropoietic Porphyria (EP)
Identify the type of porphyria
Coproporphyrinogen oxidase is deficient
Hereditary Coproporphyria (HCP)
Identify the type of porphyria
Increased isocoproporphyrin
and uroporphyrin
- Porphyria Cutanea Tarda (PCT)
- Hepatoerythropoietic Porphyria (HEP)
Identify the type of porphyria
Increased ALA and PBG
Hereditary Coproporphyria (HCP)
Identify the type of porphyria
Harderopoporphyria
Hereditary Coproporphyria (HCP)
Identify the type of porphyria
South African Porphyria
Variegate Protoporphyria (VP)
Identify the type of porphyria
Protoporphyrinogen oxidase is deficient
Variegate Protoporphyria (VP)
Identify the type of porphyria
There is increased protoporphyrin and coproporphyrin in stool
Variegate Protoporphyria (VP)
