Article on porphyrias

[Guest guest]

An excellent and detailed link on porphyrias, focused

on environmental causes (chemicals, etc) but would

also include those bacterially derived. Some of you

chemists may find their diagrams informative.

http://www.herc.org/news/mcsarticles/daniell-full.html#sec

I'll include here a quote on lab testing for this from

the webpage:

"

Laboratory Evaluation--Diagnosis of Porphyria

The nature and pattern of a patient's symptoms and

physical signs may provide some guidance in the

selection of tests for evaluating the symptomatic

patient with suspected porphyria. However, the

neurologic and cutaneous manifestations of porphyrias

can be nonspecific or atypical and caution is

necessary to avoid being overly focused on the basis

of clinical appearance in initial test selection.

Reviewers make slightly different recommendations

regarding the appropriate panel of first-line tests

for the evaluation of suspected porphyria. The most

common recommendation--when symptoms suggest possible

neurologic manifestation(s) of an acute porphyria--is

for the measurement of PBG with or without ALA in

urine (46,52,54,189). Most reviewers also recommend

quantification of total or individual porphyrins in

urine and, routinely or supplementally, in

stool--particularly when symptoms or signs suggest

possible cutaneous manifestations of porphyria.

Measurement of protoporphyrin in blood is often

recommended, depending on the degree of suspicion for

erythropoietic protoporphyria. (10)

alternatively recommends measurement of total plasma

porphyrins, plus urine PBG and ALA, to determine the

presence or absence of porphyria. A blood lead level,

with or without a ZPP level, should also be considered

because of the similarity of symptoms in lead

poisoning and porphyrias with neurologic

manifestations.

It is generally less difficult to determine whether a

patient has porphyria than it is to differentiate

which specific type of porphyria is present. The

presence or absence of increases in urinary ALA and

PBG and the relative increases in the individual

porphyrins are particularly helpful in diagnosis. The

nature and pattern of reported symptoms can assist in

differentiation. The cited general references and

review articles (1-10,46,52,54,189) provide

information regarding the patterns of laboratory

abnormalities to consider in attempting to

differentiate the specific type of porphyria in the

patient who has laboratory and clinical evidence

consistent with a porphyria. We will not discuss

further this level of differential diagnosis; we will

focus on preliminary screening steps in the diagnostic

evaluation of a possible porphyria. "

Jim