The test checks if there’s more than 50 ng/mL of cortisol in the saliva sample. If there is, the result is positive. The kit doesn’t tell you how far above the cut-off the sample was. 

If you’re having the test because you’ve been feeling unwell, the professional reading it can look at the result alongside your symptoms and decide if it’s worth doing any further tests.

If your GP has asked for a saliva sample at bedtime, use the kit and collection time they give you. They may be checking if your cortisol falls at night as expected. The lab measures how much cortisol is in the sample, and your clinician compares that number with the range they’d expect at that hour.

With Rezure’s rapid test, the professional who collects the sample can read the result there and then, without sending it away. They get a positive or negative result based on the kit’s cut-off. 

If you’ve just had a drink, even water, wait at least 30 minutes before giving your sample. The same goes for food, chewing gum and tobacco. 

Tell the person taking the sample if your gums are bleeding, as blood in the saliva can interfere with the test.

Say one sample was taken at 8 am and the other at 8 pm. If you usually sleep at night, you’d expect cortisol to be higher in the morning, around the time you wake, and lower by the evening. 

That can happen on an ordinary day when you feel much the same from breakfast to bedtime. If samples are being collected on different days for comparison, make a note of the time each one was taken and aim for the same hour where practical. 

Learn more on our blog: When is the best time to test cortisol?

No. The kit has one cut-off, 50 ng/mL, and a negative result means the saliva sample came in below it. Cortisol changes over the course of a day, so the time the sample was taken is part of the picture.

If you had the test because something’s been bothering you and it’s still happening, speak to your GP. Tell them what prompted the test and bring the result, along with the time of collection if you have it.

Specificity is easiest to picture if you start with samples that should all come back negative. At 98.7% specificity, the kit would correctly call about 987 out of 1,000 of those samples negative. The other 13 would come back positive by mistake.

The 97.3% accuracy figure covers the whole set of samples in the manufacturer’s evaluation. It counts the positives the kit got right as well as the negatives.

If you’ve already collected saliva in a cup, start again with a fresh sample. The instructions for this kit have you collect saliva straight onto the absorbent tip under the tongue. 

The collector is part of the test itself, so you use the same device from collection through to the result.

Yes. The pack contains the test device with its cap and the instruction leaflet. The collection tip is already fitted, so you can leave the swabs and sample pots in the cupboard. 

The one thing to have handy is a timer for reading the result.

Yes. To get a quote, tell us roughly how many cortisol tests you need and when you need them. If you expect to order regularly, give us an idea of how many you’d use in a typical month. 

We can quote for a one-off order or discuss a repeat supply. Ask about bulk pricing

Yes. Steroid medicines are worth flagging before you give a saliva sample, and that includes inhalers and creams as well as tablets. 

Tell the person carrying out the test what you use and when you last took or applied it. Keep taking prescribed medicine as usual unless the person who prescribed it advises you to change how you take it.

Speak to the healthcare professional who arranged the test. If you’re taking the result to your GP, tell them why you had the test and, if you know, when the sample was taken.

The result means the cortisol in that sample was above the kit’s 50 ng/mL cut-off. The next step depends on what prompted the test in the first place. Your GP may ask about your symptoms and medicines, then decide if a blood test, a urine test or a timed saliva sample would help.