The most useful laboratory tests for confirming a diagnosis of acute porphyria in primary care are the measurement of urinary porphobilinogen (PBG) and aminolevulinic acid (ALA) during an acute attack. These tests are highly sensitive and specific for acute hepatic porphyrias and can be performed rapidly to support diagnosis.
Specifically, a spot urine sample collected during symptoms should be tested for elevated PBG and ALA levels, as these metabolites accumulate due to enzymatic defects in the heme biosynthesis pathway characteristic of acute porphyria.
Additionally, total urinary porphyrins may be measured but are less specific and mainly supportive.
If initial biochemical tests are positive, referral for confirmatory genetic testing and specialist evaluation is recommended.
This approach aligns with updated expert recommendations emphasizing the importance of early biochemical screening in primary care to avoid diagnostic delays and inappropriate treatments.
In summary, the key initial diagnostic tests in primary care are urinary PBG and ALA assays performed during symptomatic episodes.
NICE NG132 Anderson et al. 2021 Aarsand et al. 2025
Key References
- NG132 - Hyperparathyroidism (primary): diagnosis, assessment and initial management
- PH43 - Hepatitis B and C testing: people at risk of infection
- NG12 - Suspected cancer: recognition and referral
- (Anderson et al., 2021): Biochemical Diagnosis of Acute Hepatic Porphyria: Updated Expert Recommendations for Primary Care Physicians.
- (Aarsand et al., 2025): Practical recommendations for biochemical and genetic diagnosis of the porphyrias.