A battery manufacturing worker develops gum pigmentation, peripheral neuropathy with wrist drop, and cognitive decline. The MOST appropriate investigation to confirm occupational exposure is:

• A Serum zinc protoporphyrin (ZPP)
• B Nerve conduction velocity alone
• C Erythrocyte sedimentation rate
• D 24-hour urinary delta-aminolevulinic acid (ALA) and blood lead level ✓

Explanation

This presentation (Burton's line on gums, wrist drop, and neurocognitive decline) is classical chronic lead poisoning. Blood lead level is the gold standard for current exposure. 24-hour urinary delta-ALA (ALAU) is elevated because lead inhibits ALA dehydratase in heme synthesis, making it a sensitive biochemical marker of lead toxicity. ZPP (zinc protoporphyrin) reflects accumulated exposure over the lifespan of red cells (90-day average) and is useful for occupational surveillance, but urinary ALA reflects ongoing exposure more acutely. Together, blood lead and urinary ALA confirm the diagnosis.

Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.