Wednesday, July 13, 2011

Saliva diagnosis, biomarkers: Spit mirrors health better than blood; saliva tests gaining momentum; could predict diseases well in advance; accurately diagnose health issues

By Syed Akbar
Hyderabad: Spit has always been considered something derogatory and insulting, but now Indian scientists and doctors have reopened the 2000-year-old secret about this wonderful fluid. Spit or saliva is more than a chemical secretion in the mouth. It is a reflection of one’s health – both mental and physical, city researchers point out.
The importance of saliva in diagnosis of diseases was extensively dealt with in ancient Indian medical records as old as 2000 years. Sushruta Samhita had made several references to saliva in diagnosis and treatment of certain diseases including oral cancers.
But, for almost two millennia the importance of saliva in diagnosis and treatment of diseases was under wraps. Digging into old Indian medical records, doctors and researchers in the country have rediscovered the significance of saliva as a non-invasive and painless diagnostic tool.
Of late, many Indian scientists have taken up research on saliva and developed biomarkers for a plethora of diseases. Saliva is both predictive and diagnostic in nature – it not only predicts well in advance whether a particular individual is pre-indisposed to a particular disease, but also tells doctors what disease an individual is suffering from.
If the fast-paced research on saliva is any indication, saliva will soon emerge as the most preferred diagnostic tool for diseases and disorders. Though they may not altogether replace the blood tests, saliva tests will come handy for small children and the elderly. Moreover, unlike blood tests which have to be largely carried out in a laboratory, saliva tests can be done in the privacy of one’s home or office, researchers point out.
Doctors at the city-based Nizam’s Institute of Medical Sciences have already successfully utilised both these (predictive and diagnostic) properties of saliva. They helped in the development of biomarkers for diabetes. Researchers elsewhere have found out that saliva is capable of informing whether or not a woman is pregnant. All that a woman, who wants to test her pregnancy, has to do is to spit on a special strip. The medicated strip will inform her if she is carrying. The NIMS-aided glycoproteomase tests can be conducted at home. A diabetic needs just to spit on the glycoproteomase strip and within no time, he 
or she will be able to know glucose control in the blood.
Ancient medical records have equated saliva with blood. Modern doctors hundreds of years later, point out that saliva is indeed a better diagnostic tool than blood. Says Dr PV Rao, head of the department of diabetology, Nizam’s Institute of Medical Sciences, “saliva mirrors blood. In fact, the diagnostic results obtained from saliva are better than those obtained from the blood. Saliva tests are painless and non-invasive. There’s no need for painful needle pricks for blood tests. In case of diabetics, dozens of blood 
tests are conducted every year. Saliva glycoproteomase tests may replace blood tests for diabetes”.
Doctors at NIMS took up the research on saliva as it is almost reflection of what lies in the blood. Study of saliva will inform doctors about the changes or otherwise in the blood. Saliva tests are convenient, handy and easy to carry out. Saliva can be stored for longer periods unlike the blood.
According to senior oral pathologist and microbiologist Dr Manjul Tiwari, diagnosis and prevention of diseases using human saliva is about to be explored as more and more laboratories and medical practitioners get ready for this new technology. “Unlike blood testing, saliva analysis looks at the cellular level, and therefore, saliva is truly a representative of what is clinically relevant,” he points out.
Blood analysis, on the other hand, looks at compounds as they travel through the blood serum. Saliva analysis will predict, diagnose, or prevent many health problems and diseases. “Molecules freely travel through the cells and into saliva ducts and it is these small molecules that can be assayed in saliva,” Dr Tiwari said.
Researchers point out that saliva tests will help in identifying health issues relating to heart, skin, cancers, and infertility. Diseases like diabetes can be predicted at least 10 years in advance through saliva tests. Cholesterol, sleep disorders, sleep disorders, baldness in men, allergies can also be identified through spit analysis.
“Other areas where saliva diagnostics will of great help include oral carcinoma, salivary gland disorders/diseases, some benign and malignant tumors, dental caries and disorders or diseases due to drugs. In India, saliva tests are yet to take off on a large scale. Hospitals in a few areas are using saliva as a diagnostic kit and in many cases it is much more effective than blood,” he said.
According to Dr Rao, a number of proteins have been identified in human saliva. Most of the proteins identified in saliva are also present in blood. Saliva diagnostics are faster and cheaper than blood tests. The diabetes tests using saliva samples will be available for the common man in the next few months.
“It works like thermometer. Put the saliva glycoproteomase strip in the mouth and the result is displayed within a few seconds. Unlike blood sugar tests where blood sampling is done before and after meals, saliva test can be done only once. This saves time and money for diabetics,” he adds.
Stating that while saliva tests won’t replace blood tests for all diagnostic applications, Dr Tiwari argues that in future they could prove to be a potentially “life-saving alternative to detect diseases where early diagnosis is critical, such as certain cancers”.
“If we could read the stories of diagnostic information present within saliva, then the abundance of information waiting to be found could be comparable to a vast vault of information such as the internet,” Dr Tiwari adds.

Facts about saliva diagnostics

* A diabetic patient with uncontrolled blood sugar undergoes 100 blood tests a year on an average. Sugar control in the body can be found out through saliva tests. Saliva test is painless, easy and more reliable than a blood test. Just spit on a strip and the result is out in no time.

* Saliva test is convenient for young children and the elderly and those who do not want to be pricked by a needle.

* Saliva analysis will reveal well in advance whether an individual is likely to develop a particular disease at a later stage in life. Biomarkers for a number of diseases are being developed.

* Saliva will inform whether a woman is pregnant. Progesterone levels in saliva are measured to confirm pregnancy.

* Saliva tests will indicate about an impending heart problem. They will tell us the level of cholesterol in the blood.

* Though saliva tests have assumed importance of late, spit was used as a diagnostic tool by doctors in ancient India, China, Greece and Rome. In olden days the smell and thickness of saliva was measured to identify diseases including cancers.

* Saliva gives a better picture of the physiology of the body than blood.

* Presently, swine flu or novel human influenza H1N1 is diagnosed through saliva or throat swab. Even tuberculosis is diagnosed through spit.

* Development of saliva biomarkers for diseases will help in better surveillance of health.

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