Buzz
Medical training emphasizes the use of all senses to diagnose patients effectively. While doctors primarily rely on visual examinations and tools like stethoscopes to assess heartbeats, the sense of smell is often overlooked. However, it can be a powerful tool in identifying specific diseases and conditions.
This list includes diseases that produce unique and unexpected odors. While some scents may be more agreeable than others, the potential of using smell as a diagnostic tool is highly promising. Certain odors on this list are so subtle that specialized equipment is needed to detect them.
10. Diabetic Ketoacidosis
Poorly managed diabetes can lead to insufficient insulin production, preventing glucose from being stored in tissues. Without glucose, cells cannot generate energy, forcing the body to break down fat instead. This process produces ketones, which are the byproducts of fat metabolism.
Acetone is commonly associated with nail salons, but it’s also a substance our bodies produce through fat breakdown and ketone formation. In diabetics, extremely low sugar levels can trigger a dangerous condition called diabetic ketoacidosis, where ketone levels rise to hazardous amounts.
Interestingly, the breath of someone experiencing diabetic ketoacidosis carries a distinct, fruity odor due to the acetone produced. This scent is detectable not only by humans but also by trained dogs, which can alert patients to dangerously high blood sugar levels.
9. Maple Syrup Urine Disease
Picture a bathroom perpetually filled with the aroma of maple syrup. This is the reality for individuals with maple syrup urine disease (MSUD), a rare genetic disorder that disrupts the breakdown of specific amino acids like valine, leucine, and isoleucine. These amino acids are excreted in urine, producing a unique and unmistakable scent.
Despite its sweet-sounding name, MSUD is far from benign. Infants born with the condition may appear healthy initially but can quickly develop severe complications, including brain damage or death, if untreated. In later stages, symptoms such as weight loss, diarrhea, erratic behavior, and hallucinations may occur. The characteristic maple syrup-like odor of urine often serves as an early warning sign of these symptoms.
Patients must carefully manage their consumption of branched-chain amino acids, as these are present in a wide variety of foods. Although there is no cure for the disease, symptom severity can be mitigated through proper dietary control and management.
8. Migraines
Dogs appear to possess a remarkable sensitivity to changes in their owners' health. A study conducted by the University of Pittsburgh explored how dogs behaved in response to their owners' migraines. Participants who experienced migraines and owned dogs were surveyed to observe their pets' reactions.
The study revealed that 25% of migraine sufferers noticed significant changes in their dog’s behavior up to two hours before a migraine began. While these findings are intriguing, the study had notable biases, and further research is necessary to draw definitive conclusions.
Many migraine sufferers experience an aura or prodrome before the onset of a migraine. These warning signs can include yawning, frequent urination, or neurological symptoms, enabling individuals to start early treatment or take preventive measures to lessen the migraine's impact.
How do these dogs alert their owners, you might wonder? A small case study involving migraine-sensing dogs revealed a range of behaviors. One owner reported her dog barking, spinning in circles, and wagging its tail excitedly. Another described their dog whining and persistently nudging them. Whether these behaviors are coincidental or directly linked to migraines is still unclear. However, for migraine sufferers, any early warning could provide crucial time to seek preventive care, making the idea of an “early alert system” incredibly promising.
7. Arsenic Poisoning
Arsenic, a chemical with centuries of use in pesticides, ammunition, and more, often contaminates groundwater, exposing humans to dangerous levels. Remarkably, residents of a remote Andean village in Argentina have developed a tolerance to arsenic concentrations 20 times higher than the safe threshold.
Historically, arsenic has been a tool for assassinating royalty, leaders, and even racehorses. It disrupts energy production in the body by inhibiting vital enzymes. Symptoms of arsenic poisoning include vomiting, abdominal pain, encephalopathy, bloody diarrhea, and, ultimately, death. A distinctive symptom noted by many is a garlic-like odor emitted from the victim’s body. Intriguingly, researchers have found that garlic itself may help counteract arsenic’s toxic effects.
Arsenic isn’t the only poison associated with unusual odors. Cyanide poisoning, for instance, has been known to produce an almond-like scent from the affected individual.
6. Phenylketonuria
If you’ve ever seen a warning about phenylalanine on a diet soda label, you might have questioned its significance. Phenylketonuria (PKU) is a genetic disorder that prevents the breakdown of the amino acid phenylalanine. Individuals with PKU must avoid foods containing this compound, including those with aspartame, a common artificial sweetener found in diet beverages.
Untreated PKU can result in intellectual disabilities, seizures, and behavioral issues. Many countries screen newborns for this condition, enabling parents to begin treatment promptly. A notable symptom of phenylalanine buildup is a musty, often described as “mouse-like,” odor. This distinctive smell led to the disease’s discovery in 1934 when a mother of two children with intellectual impairments approached Dr. Asbjorn Folling, noting the unusual scent. Analysis of their urine samples ultimately identified the disorder.
5. Typhoid Fever
A 1976 medical journal highlighted that typhoid fever patients emit an odor strikingly similar to freshly baked bread. While this might sound appealing, the reality of suffering from typhoid fever is far from pleasant.
Typhoid fever is a bacterial infection caused by Salmonella Typhi. Symptoms range from mild to severe and include a gradual onset of high fever, weakness, abdominal pain, constipation, and a rose-colored rash. Though rare in developed nations, it remains prevalent in regions with poor sanitation. Antibiotics can treat the disease, but increasing resistance poses a challenge.
Beyond typhoid, other preventable diseases linked to distinct odors include the sweet-smelling diphtheria and the unique scent associated with smallpox.
4. Narcolepsy
Narcolepsy is a debilitating condition causing sudden, uncontrollable sleep episodes at inappropriate times. Symptoms also include excessive daytime sleepiness, hallucinations, sleep paralysis, and cataplexy—a sudden loss of muscle control triggered by strong emotions. Despite these distinctive symptoms, many patients endure years without a proper diagnosis.
Narcolepsy results from a deficiency in hypocretin, a brain chemical produced by the hypothalamus. Hypocretin acts as an alertness regulator, maintaining wakefulness and controlling sleep cycles. Similar to migraines, narcolepsy may also produce a unique odor detectable by others.
A study gathered sweat samples from narcolepsy patients and healthy individuals, presenting them to two trained dogs. Neither the dogs nor their handlers knew which samples belonged to whom. Remarkably, the dogs accurately identified the narcolepsy patients' samples in most cases.
Mary McNeight, training director at the Service Dog Academy, explains that these dogs can alert patients up to five minutes before an episode. This advance warning allows individuals to find a safe place, inform someone nearby, or take other precautions to avoid injury. The dogs are trained to position themselves in front of the patient, providing support to prevent falls. Additionally, they can remind patients to take medication or assist with balance while moving. Although the specific compound causing the odor remains unidentified, this discovery offers significant hope for narcolepsy sufferers.
3. Parkinson’s Disease
In 1975, Joy Milne noticed a peculiar odor emanating from her husband, Les. She often accused him of not showering or brushing his teeth properly, even though he had. Convinced the smell was unusual, she persisted, though her comments frustrated him. It wasn’t until a decade later that Joy understood the source of the scent.
Les was diagnosed with Parkinson’s disease at 45. This neurodegenerative disorder stems from the loss of dopamine-producing neurons, leading to symptoms like tremors, slowed movement, stiffness, and walking difficulties. While there’s no cure for Parkinson’s, various treatments can help manage its symptoms.
Currently, no definitive diagnostic test exists for Parkinson’s beyond observing symptoms. Joy, a retired nurse, only connected the musky odor to the disease after meeting other patients at a support group.
Studies are now underway to validate Joy’s unique ability. In one test, she accurately identified all Parkinson’s patients from six T-shirts worn by patients and six by healthy individuals. Interestingly, she flagged one control as having Parkinson’s, and that individual was diagnosed three months later.
Joy is participating in studies to identify the compound responsible for the distinct odor she detects. Dr. Kunath and Professor Perdita Barran are using mass spectrometry to isolate ten molecules unique to Parkinson’s patients. While research is ongoing, this breakthrough could pave the way for a new diagnostic tool for the disease.
2. Schizophrenia
During the 1960s, nurses noted a peculiar smell in the wards of mental hospitals, sparking curiosity among researchers. Smith and Sines hypothesized that the odor was linked to schizophrenia, describing it as a persistent “skunk-like” scent, particularly noticeable in catatonic patients, regardless of hygiene practices.
A study compared the sweat of schizophrenia patients to that of healthy individuals. Both human odor testers and trained rats consistently detected the unique scent in patients’ sweat. Later, Smith and Sines identified the compound responsible as trans-3-methyl-2-hexenoic acid (TMHA) using advanced laboratory methods.
This discovery was groundbreaking at the time, offering a potential biological marker for mental illness. The search for an “endogenous schizotoxin” believed to cause the disorder gained momentum in the early 1970s. However, subsequent attempts to replicate the findings, including by the original team, failed. While TMHA is a significant component of sweat, especially in Caucasians, no definitive link to schizophrenia has been established.
In 2005, the theory resurfaced when a research team suggested that a broader variation in body odor, rather than a single compound, might be unique to individuals with schizophrenia. However, no further studies have confirmed or expanded on these findings.
1. Bacterial Infections
Pseudomonas aeruginosa is a bacterium responsible for various infections in humans. It is known for its blue-green pigmentation and commonly affects individuals with diabetes, cystic fibrosis, burn injuries, or drug use. This opportunistic pathogen thrives in hospital settings and can become life-threatening if not treated promptly. If you’ve ever experienced hot tub folliculitis, you’ve likely encountered Pseudomonas.
While laboratory methods exist to identify Pseudomonas, one unique feature is its grape-like odor, attributed to the compound 2-aminoacetophenone. Although not a formal diagnostic marker, this scent appears early in the bacteria’s growth cycle, making it a potential identification tool. Interestingly, some describe the odor as resembling tortillas rather than grapes.
Pseudomonas isn’t alone in producing distinctive smells. For instance, E. coli, a common culprit in food poisoning, emits a floral scent. Eikenella corrodens, often causing infections from human bites, smells like bleach. Meanwhile, Streptococcus anginosus, which can lead to abscesses, has a sweet, caramel-like aroma. While these odors might seem appealing, it’s best to avoid close contact with these harmful bacteria.
+ Cancer
Scientists are constantly exploring methods to detect cancer early, as timely diagnosis can significantly improve patient outcomes. While much remains unknown about how cancer alters the body, changes in body odor are one of its many effects. Dogs, renowned for their extraordinary sense of smell, assist in tasks like drug detection and search-and-rescue missions. However, their potential in cancer detection is often overlooked.
Lucy, a Labrador Retriever and Irish Water Spaniel mix, was dismissed from guide dog training due to her exceptional olfactory abilities. Her owners decided to harness her talent by training her to detect cancer. Over seven years, Lucy successfully identified bladder, kidney, and prostate cancers. Today, she participates in one of the largest clinical trials for canine cancer detection.
Medical Detection Dogs is an organization featuring eight dogs trained to identify cancer through human urine samples. Founder Claire Guest was inspired to start the group after her Labrador, Daisy, detected deeply embedded breast cancer.
One of the earliest documented cases of dogs detecting cancer dates back to 1989, when doctors at King’s College reported a woman whose dog repeatedly sniffed a mole on her leg. The mole was later diagnosed as an early-stage malignancy.
Researchers believe dogs detect alkanes or aromatic compounds produced by cancerous cells. These volatile substances can be identified by dogs in human breath or urine, offering a non-invasive method for early cancer detection.
Although the concept makes for eye-catching headlines, securing funding for this research has proven challenging. Existing studies provide compelling evidence supporting dogs' detection capabilities. However, skepticism remains regarding the practical and clinical viability of these findings, as well as potential confounding factors in the research.
