Urinalysis and Body Fluids 6th Edition by Majorie DiLorenzo, Susan Strasinger

Exercise 29

The two stages of heme formation affected by lead poisoning are:

A. Porphobilinogen and uroporphyrin

B. Aminolevulinic acid and porphobilinogen

C. Coproporphyrin and protoporphyrin

D. Aminolevulinic acid and protoporphyrin

Step 1 of 2

Porphyrinuria:

It is the presence of excess porphyrin in urine also termed as porphyria.

• Porphyrins are intermediate compounds, which help in production of heme

• Disorders in metabolism of porphyrin are collectively called as porphyrias

• Porphyrin is formed from heme synthesis through glycine, and succinyl coA

->aminolevlinate (ALA) ->porphobilinogen->hydroxymethylbilane

->uroporphyrinogen->coproporphyrinogen->protoporphyrinogen

->protoporphyrin IX->heme

• When aminolevulinate is transformed to porphobilinogen by aminolevulinic acid synthetase lead exposure is caused at this stage

• Lead poisoning is also seen in protoporphyrin stage

Therefore, two stages in heme synthesis affected by lead poisoning are “aminolevulinic acid, and protoporphyrin” stage. Hence, the correct answer is option.