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PBG Urine testing
The PBG Urine test is a test that measures the
of porphobilinogen in the urine. Another name for
the test is the PHB test.
The test of completed by collecting a 24-hour urine
The test must be ordered by your physician.
Your physician will instruct
you as to what drugs you may have to
discontinue because some drugs may interfere with
the test results. It is impereative that you do not use
certain drugs or use any alcohol for a week prior to
collection of the test.
Also please note that you are NOT to undergo glucose
injection or infusion until after the collection has been
made. The use of glucose will dramatically reduce
porphyrin levels in the test results.
Before you leave the physician's office, be sure that the
collection jug has the correct preservative within the
jug. On day 1,
urinate into the toilet upon arising in the morning.
subsequent urine in a special container called a "hat"
for the next 24-hours.
But sure to
try and void in as limited of light as possible. Exposure
of the urine to light will diminish the total porphyrins
and the object of the test is to have as high as possible
count of porphyrins.
Also note that
of the collection toexposure to air will diminish
the porphyrins and therefore you should never let the
voided urine stand in
the hat, but immediately.
On day 2,
urinate into the "hat" and immediately
pout into the
container in the morning upon arising.
Be sure that
the cap is on the container at all times.
Keep it in the refrigerator or a cool place during the
Be sure that
the collection jug is labeled with your name, the date,
the time of completion.
next step is to return the collection jug
by your physician. To safeguard your collection and
to be sure that
it is not compromised, accompany it to the lab, and go
with it to the
area where it is being stored and see it safety
refrigerated. Remember that
many a collection sample has been compromised because it
was left unattended on a lab counter in light and heat.
Find out when it is being shipped and to whom. When it is
expected to arrive and when the results are expected to
be completed and returned.
directions of your phyrisician immediately deliver the
collection jug. Be sure that it is refrigerator
This test may is performed when porphyria or
associated with abnormal PBG level is suspected.
PBG is a substance (enzyme) used by the body to
porphyrins (nitrogen containing organisms).
The important function of porphyrins is as components of
Heme is made
from iron + protoporphyrin. Hemoglobin is made up of four
globin proteins + 4 heme groups. Oxygen binds to the iron
in the heme molecules.
Various kinds of porphyrins exist with the same basic
but with slightly different chemical appearance.
The major biochemical pathway includes conversions from
porphyrins to delta-ALA, then to PBG, then uroporphyrin,
then coproporphyrin, then protoporphyrin, and finally
into the end product, heme.
Each step requires the presence of an enzyme. If any of
the enzymes are deficient (because of a genetic disease
or inhibition by a toxic substance), a type of porphyria
results. The following are the normal values for the PBG
24-hour urine test. 1.5 to 2 mg (milligrams) per 24-hours
Many drugs can affect the results of the PBG 24 urine
test. Drugs that can affect test measurements include
acid, barbiturates, chloral hydrate, chlorpropamide,
ethyl alcohol, griseofulvin, morphine, oral
contraceptives, phenazopyridine, procaine, and
sulfonamides. Abnormal increased levels of urinary PBG
may indicate several types of porphyria. In addition
elevated PBG may indicate hepatic carcinoma (liver cancer)
, cirrhrosis, hepatitis, and lead poisoning.
Dr. Robert Johnson MD