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TESTING FOR PORPHYRIA



PBG   Urine testing


            The PBG Urine test is a  test that measures the amount
of porphobilinogen in the urine. Another name for the test is the PHB test.

            The test of completed by collecting a 24-hour urine sample.
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.

        Collect all 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 collection period.

        Be sure that the collection jug is labeled with your name, the date,
the time of completion.

        Then  the next step is to  return  the collection jug  as instructed
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.

        Ask questions. 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.

        Following the directions of your phyrisician immediately deliver the
collection jug.  Be sure that it is refrigerator upon receipt.

            This  test may is  performed when porphyria or another disorder
associated with abnormal PBG level is suspected.

            PBG is a substance (enzyme) used by the body to synthesize
porphyrins (nitrogen containing organisms).

            The important function of porphyrins is as components of heme.

        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 structure,
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 aminosalicylic
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

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