Feasibility of using paper impregnated with urine instead of liquid urine for assessing ovarian activity

Ovarian activity should ideally be assessed by serial non-invasive methods that require simple procedures for sample collection and storage. Measurement of urinary oestrone-3-glucuronide and pregnanediol-3 alpha-glucuronide is a non-invasive method available for assessment of ovarian activity, but transport of large numbers of urine samples is cumbersome and samples need to be stored frozen. An alternative sample collection, transport and storage procedure that is easier to handle and requires no or minimal cold storage facilities will particularly benefit studies in which ovulatory activity needs to be assessed in field settings. To evaluate the feasibility of using paper impregnated with urine as an alternative to liquid urine for the measurement of oestrone-3-glucuronide and pregnanediol-3 alpha-glucuronide concentrations in the assessment of ovarian activity. Urine samples collected daily throughout regular menstrual cycles were stored as liquid urine at -20 degrees C, and as paper impregnated with urine, in the refrigerator for 3 to 12 months or at room temperature for 1 to 6 months. Oestrone-3-glucuronide and pregnanediol-3 alpha-glucuronide concentrations were measured in these urine samples by enzyme immunoassay. Values obtained were correlated using Spearman's correlation test. The pattern of oestrone-3 glucuronide and pregnanediol-3 alpha-glucuronide concentrations estimated using paper impregnated with urine followed that of liquid urine in all storage conditions used. Values obtained by two methods correlated significantly (p < 0.001 to 0.0001) though the paper impregnated with urine gave slightly higher values. Paper impregnated with urine can be used to facilitate sample collection, transport and storage of urine when oestrone-3-glucuronide and pregnanediol-3 alpha-glucuronide measurements are required in a large number of serial samples to assess ovarian activity.