Reference Interval Ranges Components Ref. Int. Arsenic, Urine 0.0-35 ug/l Arsenic, Urine (24 hour) 0.0-50 ug/d Arsenic per gram creatinine No reference interval (ug/g crt) Creatinine(24 hour) Male 3-8 years: 140-700 mg/d 9-12 years: 300-1300 mg/d 13-17 years: 500-2300 mg/d 18-50 years: 1000-2500 mg/d 51-80 years: 800-2100 mg/d 81 years and older: 600-2000 mg/d Female 3-8 years: 140-700 mg/d 9-12 years: 300-1300 mg/d 13-17 years: 400-1600 mg/d 18-50 years: 700-1600 mg/d 51-80 years: 500-1400 mg/d 81 years and older: 400-1300 mg/d

Specific toxic thresholds for arsenic are not well defined. The ACGIH Biological Exposure Index is 35 ug/L for the sum of the inorganic and methylated forms of arsenic. For specimens with a total arsenic concentration between 35-2000 ug/L, fractionation is performed to determine the proportion of organic, inorganic and methylated forms. If low-level chronic poisoning is suspected, the ug/gCRT ratio may be more sensitive than the total arsenic concentration. It may be appropriate to fractionate specimens with a ug/gCRT ratio >30 ug/gCRT despite a total arsenic concentration <35 ug/L; the laboratory will perform this on request. The organic forms of arsenic, most commonly arsenobetaine, are considered nontoxic and arise primarily from food. Inorganic forms of arsenic [As(III) and As(V)] are most toxic. Methylated forms (MMA and DMA) arise primarily from metabolism of inorganic forms but may also come from dietary sources and are of moderate toxic potential. As this test does not detect all species of arsenic, it is expected that the sum of the organic, inorganic and methylated forms will not equal the total arsenic concentration.

Record: Total volume and collection time on test requisition. Commercial laboratory studies indicate that refrgieration of urine alone, during and after collection, preserves specimen as well as any alternative preservatives added before collection, if specimen is tested within eight days of collection. To differentiate between organic and the more toxic inorganic forms, an arsenic speciation test is recommended and can be performed with the existing specimen by contacting the clinical laboratory lead scientist at pager 131-7283. If urine, arsenic is abnormal, additional testing is performed by the reference laboratory. The patient will be charged for this testing when applicable.