ALA Dehydratase Deficiency Porphyria Workup
- Author: Smeeta Sinha, MD; Chief Editor: Emmanuel C Besa, MD more...
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)
DNA analysis to identify mutations in the ALAD gene is the most specific test for ALAD deficiency porphyria (ADP).
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