NURSING ANM AND GNM

Detailed explanation-1: -Because of its lack of specificity, man workers have discouraged its use [3-5]. In 1964, Culliford and Nickolls [1] published an in-depth review of the benzidine test. They found that false positives could be obtained from blood contamination, chemical oxidants, catalysts, and vegetable peroxidases.

Detailed explanation-2: -Only elevated thallium levels in hair, nails, blood, urine, feces and saliva can make a definitive clinical diagnosis. A 24-hour urine thallium concentration, assayed by atomic absorption photospectrometry, is the standard method. Although a urine spot test is faster, it has a high false-positive rate.

Detailed explanation-3: -A positive result from a presumptive test for blood indicates the possibility that blood is present. A positive result from a confirmatory test allows one to conclude that blood is present.