ALA Dehydratase Deficiency Porphyria Workup

Updated: Mar 25, 2021
  • Author: Smeeta Sinha, MD; Chief Editor: Emmanuel C Besa, MD  more...
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Workup

Laboratory Studies

Findings on laboratory studies in patients with delta-aminolevulinic acid dehydratase (ALAD) deficiency porphyria (ADP) are as follows:

  • Urine ALA levels are increased and correlate with the clinical severity

  • Erythrocyte zinc protoporphyrin levels are markedly elevated

  • Urine coproporphyrin III and protoporphyrin IX levels are also elevated

  • Erythrocyte ALAD activity is typically decreased by greater than 80% of normal

  • Despite the fact that this is a disease of hemoglobin synthesis, the complete blood cell count (CBC) remains within the reference range

  • Urine porphobilinogen (PBG) levels are within the reference range; this distinguishes ALAD deficiency porphyria (ADP) from acute intermittent porphyria, which is characterized by increased urinary excretion of PBG

  • Fecal porphyrin levels are normal

  • Blood lead levels should be tested to rule out acquired ALAD deficiency

  • Hyponatremia may be noted during acute attacks of ALAD deficiency porphyria (ADP) and is attributed to infusion of hypotonic dextrose-containing fluids or to the syndrome of inappropriate secretion of antidiuretic hormone (SIADH)

Hyponatremia and hypomagnesemia are both risk factors for development of seizures, which occur in 20-30% of acute attacks. [15]

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Other Tests

DNA analysis to identify mutations in the ALAD gene is the most specific test for ALAD deficiency porphyria (ADP).

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