Summary diagnostic algorithm for the acute porphyrias.
Suspect porphyria when appropriate,order the right tests,and collect the specimens properly.
All porphyrias are semi-treatable.
Porphyrins are a group of heterocyclic macrocycle organic compounds, composed of four modified pyrrole subunits interconnected at their α carbon atoms via methine bridges (=CH−). The parent porphyrin is porphin, and substituted porphines are called porphyrins. The porphyrin ring structure is aromatic, with a total of 26 electrons in the …
Le porfirine (dal greco porphyrá – porpora), sono una classe di composti chimici la cui molecola è caratterizzata da uno scheletro eterociclico costituito da quattro molecole di pirrolo unite tramite i ponti metinici nella posizione alfa. La struttura dell’anello porfirinico è aromatica, con un totale di 26 elettroni nel sistema coniugato. Una …
The porphyrias must be the most-hated diseasesin medicine.
Blood is an amazing and vitally important part of the body,because it contains many finely-tuned chemical systems that allowit to maintain the chemical environment needed for the body'smetabolism. One of the most important functions of blood isdelivering O2 to all parts of the body by thehemoglobin protein. O2 is carried in the hemoglobinprotein by the heme group. The heme group (a component of thehemoglobin protein) is a metal complex, with iron as the centralmetal atom, that can bind or release molecular oxygen. Both thehemoglobin protein and the heme group undergo conformationalchanges upon oxygenation and deoxygenation. When one heme groupbecomes oxygenated, the shape of hemoglobin changes in such a wayas to make it easier for the other three heme groups in theprotein to become oxygenated, as well. This feature helps theprotein to pick up oxygen more efficiently as the blood travelsthrough the lungs. Hemoglobin also enables the body to eliminateCO2, which is generated as a waste product, via gasexchange in the blood (CO2 exchanged for O2in the lungs, and O2 exchanged for CO2 inthe muscles). The species generated as waste by theoxygen-consuming cells actually help to promote the release of O2from hemoglobin when it is most needed by the cells. Hence,hemoglobin is a beautiful example of the finely tuned chemicalsystems that enable the blood to distribute necessary moleculesto cells throughout the body, and remove waste products fromthose cells.
* The traditionalscreening tests for porphobilinogen are extraction-basedtraditional-bench-chemistry testscalled the "Watson-Schwartz" and "Hoesch" tests, and you mayhear these names.
DO NOT go back and memorize the porphyrin section of Stryer!
Gung-ho clinicians now aspirateduodenal bile or cannulate the common bile duct to measure bile porphyrins(* protoporphyrin is soluble in bile but not in urine), establishing thediagnosis between attacks (NEJM 324: 1432, 1991, works great).
You must collect the urine for porphobilinogen assay in aLIGHT-PROOF BOTTLE (wrap it in aluminumfoil.) Alkalinization is no longer strongly recommended.
Porphyria in children:Mayo Clin.
MECHANISMS AND SYMPTOMATOLOGY IN THE PORPHYRIAS porphyria
groupPORPHYRIAS AT A GLANCE:
ACUTE INTERMITTENT PORPHYRIA (AIP -- see Neurology48: 1678, 1997)
Despite the problems making porphyrins, the metabolic machinery goes into overdriveso patients are seldom anemic.
suggests porphyria as the cause of Vincent VanGogh's craziness (Br.
All about the LAB DIAGNOSIS of porphyrias:NEJM 324: 143, 1991; update J.
The BASIC SCREENING TEST FOR AIP is URINARY PORPHOBILINOGEN.
DELTA-AMINO LEVULINIC ACID and PORPHOBILINOGEN are neurotoxins that produce cerebral dysfunctionand damage (confusion, "psychiatric disease", depression, anxiety,hallucinations, paranoia), autonomic neuropathy (vomiting, constipation, urinary retention, tachycardia, hypertension, often atrial fibrillation -- Am.
1: 7, 1968;case against porphyria J.
More about "MCS", later, along with why almost no one in scientific medicinebelieves in it any more, and how its proponents operate. PORPHYRIA CUTANEA TARDA (familiar as "PCT"; Medicine 89: 69, 2010)
Uroporphyrinogen is elevatedin the urine, enabling the diagnosis.
* Dividing porphyrias into "hepatic" ("caused by accumulation of precursors of the P450 cytochrome") and "erythropoietic" ("caused by accumulation of precursors of hemoglobin") is becoming unfashionable.
The small molecule is a metalloporphyrin, CuTMPyP4 [copper(II) -tetra(-methyl-4-pyridyl)porphyrin], and the DNA is a hexamer duplex, [d(CGATCG)]2.
Protoporphyria is rather common and of variable expressivity.
Mild versions are surely common and are missed by thestandard enzyme "normal ranges".* This unit will focus on what a general physician needs to know about the porphyrias.
CONGENITAL ERYTHROPOIETIC PORPHYRIA (* Gunther's disease)
Favorable electrostatic interactions appear to draw the porphyrin into the duplex interior, offsetting unfavorable steric clashes between the pyridyl rings and the DNA backbone.
"I have always been impressed by the quick turnaround and your thoroughness. Easily the most professional essay writing service on the web."
"Your assistance and the first class service is much appreciated. My essay reads so well and without your help I'm sure I would have been marked down again on grammar and syntax."
"Thanks again for your excellent work with my assignments. No doubts you're true experts at what you do and very approachable."
"Very professional, cheap and friendly service. Thanks for writing two important essays for me, I wouldn't have written it myself because of the tight deadline."
"Thanks for your cautious eye, attention to detail and overall superb service. Thanks to you, now I am confident that I can submit my term paper on time."
"Thank you for the GREAT work you have done. Just wanted to tell that I'm very happy with my essay and will get back with more assignments soon."