A suspected case of homicidal thallium poisoning presents with burning extremity pain and progressive hair loss four days after ingestion. Which finding provides the EARLIEST confirmatory clue?

• A Transverse white bands across all fingernails
• B Basophilic stippling of red cells on peripheral smear
• C Raindrop pigmentation over the trunk
• D Dark pigmentation of hair roots on light microscopic examination of plucked hairs ✓

Explanation

Thallium accumulates in the hair matrix and darkens the hair follicle root, visible on simple light microscopy of plucked hairs within 3 to 4 days of ingestion, making it the earliest bedside clue. Mees-like transverse white nail bands take roughly two to four weeks to grow out, raindrop pigmentation is a feature of chronic arsenic exposure, and basophilic stippling belongs to lead poisoning.

Reference: Parikh's Textbook of Medical Jurisprudence, Forensic Medicine and Toxicology, 6th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.