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CASE FILES: BIOCHEMISTRY
hematin can aid in reestablishing the negative regulation of ALAS during acute
attacks. With ALAS activity attenuated, the precursor backlog at the enzymatic
deficient step can begin to return to manageable levels, and the patient’s con-
dition can shift back to the compensated, symptom-free phase. After diagno-
sis of acute porphyria is confirmed, strict avoidance of environmental triggers
can prevent acute attacks. Most patients with acute porphyrias can lead a nor-
mal life; however, complications such as hypertension, chronic renal failure,
and hepatoma can become problematic.
C O M P R E H E N SIO N Q U E ST IO N S
For Questions 44-1 and 44-2 refer to the following case:
A 30-year-old white woman enters the emergency room complaining of nau-
sea, severe abdominal pain, and prolonged constipation. She appeared dis-
traught and was sweating. She described beginning an extremely low calorie
diet within the past 2 months in an attempt to lose weight. Physical examina-
tion determined rapid heart rate, moderate hypertension, and weakness in the
extremities. Also noted were mild dermatitis/blistering on her hands and scar-
ring on her face.
[44.1] You suspect porphyria. Which biochemical laboratory test(s) would be
sufficient to determine the type of porphyria?
A. Urinary ALA and PBG.
B. Urinary and fecal PBG and porphyrins.
C. Porphyrin spectrofluorometry (plasma scan).
D. None of the above is sufficient alone.
[44.2] Laboratory tests revealed elevated urinary PBG and coproporphyrin,
and plasma fluorescence emission at 626 nm. Which type of porphyria
does the patient have and what is the most likely biochemical
explanation?
A. Acute intermittent porphyria; PBGD heterozygous enzyme defi-
ciency causing PBG backlog.
B. Porphyria cutanea tarda; UROD homozygous enzyme deficiency
causing uroporphyrin backlog.
C. Variegate porphyria; PPO heterozygous deficiency causing proto-
porphyrin IX backlog.
D. Variegate porphyria; PPO homozygous deficiency causing proto-
porphyrin IX backlog.
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