I can help you with the reading of the OTC test. They are all time-sensitive and any reading beyond the designated time is meaningless. As to dilute testing through lab you should understand that dilute samples can still be tested. Any reading below 20 mg creatinine will usually be noted as dilute. But we test down to 5 mg. Therefore in the range of 5-19 mg the test is reported negative dilute or positive dilute*.

In relation to the lab test the above applies to private employers (non-regulated testing). There is a different set of rules for DOT and federally regulated testing.

*this is recommended lab practice but is ultimately determined by the ordering party. In addition some labs may require <20 creatinine and low specific gravity to class as dilute.