Saturday, May 7, 2016

Home Urine test and what the Faint Line means

Negative or Positive Test Result ?


I have found this to be a very common question with people who are worried about seeing a faint line on the home reagent dip strip test. These are a basic preliminary qualitative test and thus will not show the exact level present, only if it is over or under the detection level. The result of these tests is either positive or negative.

The kit used for urine drug test is reliable yet a cheaper way of screening the urine for signs of drugs. Every drug test involves a predetermined detection level which can tell if a drug test is positive or negative. However, it’s important to note that these tests do not give any information regarding the amount of drug present within the body. People get a faint line and get nervous, but mainly it is for THC screens, why is this ? 

What Does the Faint Line Mean?

When reading the drug test result, you will find a line at the very top of every testing window and that is the control region (C). The test is not considered valid without this line. Result is considered negative when a colored line appears in both the control (C) and test (T) region. If the colored line appears in the control region but not in the test region, the test is considered to be positive. Nevertheless, presence of any faint line in the test region (T) will indicate negative results no matter how light it is.

The color intensity of the line in a drug test result must not be confused with the quantity of drug present in the body. A positive urine drug test requires presence of minimum drug quantity in the urine specimen. In case of some drugs, the minimum drug quantity ( threshold or cut off value) is rather high such as amphetamines (1000ng/ml) whereas it’s low in other drugs such as marijuana (50ng/ml). The lower the minimum amount (threshold), the lighter the line will be in negative urine.

So a dark line is a high threshold and a faint line is a low threshold but still a negative. Remember, before you added urine there was NO LINE RIGHT?

If a test is negative, it means that the concentration of the drug in the urine sample is below the designated cutoff level set by the test. A person may still have that drug in their system, just not above the cutoff limit.

Possible cause for a VERY faint line

Dilution is also considered to be a cause of faint line on drug test but if the test has a validation screen in addition to the drug screen it will show If the creatinine and specific gravity (urine density) are in range, if they are not it indicates dilution .

Cups with a validation are a bit more expensive and not common with average home tester but are used in labs to save money instead of using a mass spec .

Sometimes a lab will use a reagent stick validation before "accepting" the sample to sent to the lab when they don't use the cups.

Now for the bad news.  I have seen many times a lab doing mass spec will skip the initial screen threshold and go straight to a confirmation level screen which is almost zero tolerance. For example THC should be initial run at 50 nl ( but is often  run at 10nl in a lab mass spec) and confirmation is 1nl ( should only be ran if you fail initial screen) and if you fail and don't call them on it then your screwed.  
If you are dirty and don't wish to go thru extended thc detox or just don't have time youre best option is substitution with a quality urine like "Fake It" Synthetic urine and a Quality device.

No comments:

Post a Comment