|Normal adult urine||Mean||95% reference range|
5.4 mg/L (± 4.95)
0.39 - 15.1 mg/L
3.17 mg/L (± 3.3)
0.81 - 10.1 mg/L
0.46 - 4.0
Table 6.3. Mean values (± standard deviation) and ranges for FLC concentrations and κ/λ ratios in early morning urine samples from 66 normal individuals .
A wide range of normal urine FLC concentrations was similarly observed by Snyder et al., who established a 95% reference range for the urine Freelite ratio of 1 - 19 using 91 healthy adult donors . The authors attributed the relatively poor diagnostic sensitivity of the urine FLC assay (80%) to the wide reference ranges and a high background of polyclonal FLC in the urine. It is important to note that international guidelines do not recommend the use of urinary FLC immunoassays . Arguments in favour of serum over urine FLC assays are further discussed in Chapter 24.