Saliva Test for Laryngopharyngeal Reflux (LPR)

Various groups have been developing a fast, cheap, non-invasive saliva swab test to determine whether laryngopharyngeal reflux (LPR) is present or not. LPR may cause symptoms of:

• Hoarseness
• Chronic (ongoing) cough
• Frequent throat clearing
• Constant mucus or phelgm in the throat
• Dry or sandpaper like sensation in the throat
• Pain or burning sensation in the throat
• Feeling of a lump in the throat (globus pharyngeus)
• Problems swallowing
• Bad/bitter taste in the mouth (especially in morning)
• Asthma-like symptoms
• Ear pain and/or persistent ear infections
• Post-nasal drip
• Large lingual tonsils

When you compare a spit test to the current way of how reflux is determined via barium swallow, upper endoscopy (EGD), and 24 hour ph/impedance testing, it sounds quite attractive.

How does such a test work?

It basically looks for a stomach protein called pepsin.

Given reflux is when stomach contents moves up towards the mouth and pepsin is a protein ONLY produced in the stomach... pepsin should NOT be found in the throat/mouth.

As such, the test can state yes or no whether LPR is present or not.

How good is the test?

Depending on the study, sensitivity ranges in the 80-100% (can actually detect reflux if truly present) and specificity is around 85% (truly no reflux if test is negative).

Unfortunately, such testing is not offered is most labs. (Currently working on getting such testing available in our office.)

One test company is rdbiomed using their Peptest kit. This test is not yet available in the United States per company representative (7/18/12).

References:
Sensitive pepsin immunoassay for detection of laryngopharyngeal reflux. Laryngoscope. 2005 Aug;115(8):1473-8.

Rapid salivary pepsin test: Blinded assessment of test performance in gastroesophageal reflux disease. Laryngoscope. 2012 Jun;122(6):1312-6. doi: 10.1002/lary.23252. Epub 2012 Mar 23.

"Mouthwatering" Foods May Be a Misnomer?

In the spirit of Thanskgiving where thoughts of food predominate, British researchers have determined that humans are NOT able to produce more saliva by merely thinking of foods whether hungry or not.

This includes looking at pictures of sumptuous foods.

What researchers did determine is that SMELLING foods increased salivary production significantly. Tasting and chewing was even more influential in salivary production.

So at least for humans, unless the food is smelled, tasted, or chewed, mouthwatering just does not happen.

Of note, salivary production was determined by placing cotton pledgets inside the cheeks (saliva produced by the parotid glands) and a suction device under the tongue (saliva produced by the submandibular glands) on healthy volunteers.

Read MSNBC report here.

Reference:
IS THE MOUTHWATERING SENSATION A TRUE SALIVARY REFLEX? Journal of Texture Studies Special Issue: Food Oral Processing - Physics, Physiology, and Psychology University of Leeds, U.K. Volume 42, Issue 3, pages 212–216, June 2011

Spit Analysis Can Reveal Person's Age

There are certain compounds in a person's spit that can reveal their age to within 5 years. No kidding. There are certain things we know about DNA. We know that DNA gets methylated (like ornaments on a Christmas tree). We also know that the methylation pattern on the DNA changes with age. So the hypothesis was whether looking at the methylation pattern of the DNA can reveal a person's age? And guess what... it does according to a recently published study.

In this study published on PLoS ONE, researchers studied the saliva of identical twins to figure out what sites appeared to correlate best with age. They narrowed it down to 88 DNA methylation sites that seemed to correlate with age. Based on these 88 sites, they than verified it in 60 men and women, ages 18 to 70, and found that two genes in particular had the strongest age correlation to within 5 years. Amazing!

This finding can certainly help with crime-fighting, but also has potential for spit being a marker for all sorts of other biological problems that have yet to be discovered (perhaps even replace painful needle sticks for blood draws). After all, if a person's spit can reveal their age, who knows what else it can reveal about the person!

Reference:
Epigenetic Predictor of Age. PLoS ONE 6(6): e14821. doi:10.1371/journal.pone.0014821