Maple syrup urine disease (MSUD) is a disorder in which the body cannot break down certain parts of proteins. The urine of people with this condition can smell like maple syrup.
Symptoms of classic MSUD appear in newborns within 48 hours of birth. In older children, signs of intermediate, intermittent, and thiamine-responsive MSUD usually develop before age seven. All four types of MSUD have symptoms including: Urine, sweat, or earwax that smells like maple syrup or burnt sugar.
Nonclassic (or variant) forms of MSUD, occurring in 20% of patients, can manifest at any age whenever residual enzyme activity is overwhelmed, for instance, by increased dietary protein or during acute illness (2).
MSUD is a lifelong condition. With treatment and dietary changes, a person can live a typical lifespan into adulthood. Children and adults need to recognize the signs of a crisis so they can get emergency treatment immediately.
People with this condition cannot break down the amino acids leucine, isoleucine, and valine. This leads to a buildup of these chemicals in the blood. In the most severe form, MSUD can damage the brain during times of physical stress (such as infection, fever, or not eating for a long time).
Maple syrup urine disease (MSUD) is a rare but serious inherited condition. It means the body cannot process certain amino acids (the "building blocks" of protein), causing a harmful build-up of substances in the blood and urine. Normally, our bodies break down protein foods such as meat and fish into amino acids.
Maple Syrup Urine Disease Symptoms
Babies with MSUD can start to have problems a few days after delivery. It only takes a few days for amino acids and their toxic byproducts to build up in the blood and urine. This causes symptoms such as: Pee or earwax that smells like maple syrup.
MSUD can be classified into four general types: classic, intermediate, intermittent, and thiamine-responsive. Classic MSUD is the most severe type. Individuals with other types exhibit milder symptoms but are prone to periods of crisis in which symptoms closely resemble classic MSUD.
If untreated, affected individuals accumulate substantial branched-chain amino acids, mostly leucine, and suffer encephalopathy within the first week of life as well as cerebral oedema and dysmyelination with chronic brain injury (Crome et al., 1961; Silberman et al., 1961; Chuang and Shih, 2001).
Classic maple syrup urine disease (classic MSUD) is the most severe and probably common form of MSUD (see this term) characterized by a maple syrup odor in the cerumen at birth, poor feeding, lethargy and focal dystonia, followed by progressive encephalopathy and central respiratory failure if untreated.
A person with uncontrolled diabetes may have blood glucose levels that are dangerously high. The body tries to get rid of the extra glucose in the urine, and this can cause a sweet smell. People with sweet-smelling urine due to diabetes may notice other symptoms, including: exhaustion.
Consequently, intermittent MSUD might go undetected in Newborn Screening (NBS) testing, and its diagnosis might be further elusive and delayed due to apparently normal BCAA levels, unless these are measured during an ongoing metabolic crisis (Puckett et al., 2010).
Since fenugreek can cause uterine contractions, it should not be taken during pregnancy. When taken for lactation, the advice that is often offered is to slowly increase the dosage until the sweat or urine begins to smell like maple syrup.
Some people with diabetes compare the smell of insulin to the scent of Band-Aids, printer ink, Lysol, or new plastic shower curtain liners (4).
If you have diabetes, a change in body odor could be a sign of diabetes-related ketoacidosis. High ketone levels cause your blood to become acidic and your body odor to be fruity. In the case of liver or kidney disease, your odor may give off a bleach-like smell due to toxin buildup in your body.
Most children with intermediate MSUD are diagnosed between 5 months and 7 years old. Like it's classic form, intermediate MSUD initially produces nonspecific symptoms including feeding problems, lethargy and poor growth, which may worsen to include seizures, brain damage, coma and life-threatening complications.
The main treatment for MSUD is a low-protein diet with low levels of the three amino acids. Babies with MSUD must be on a special formula as soon as possible. Then, they'll follow the special diet for the rest of their lives. Some also need to take nutritional supplements.
Diagnosis/testing.
Follow-up plasma amino acid analysis typically demonstrates elevated concentrations of BCAAs and alloisoleucine. The diagnosis of MSUD is confirmed by identification of biallelic pathogenic variants in BCKDHA, BCKDHB, or DBT.
Causes. Maple syrup urine disease (MSUD) is inherited, which means it is passed down through families. It is caused by a defect in 1 of 3 genes. People with this condition cannot break down the amino acids leucine, isoleucine, and valine.
MSUD is a metabolic disorder caused by a deficiency of the branched-chain alpha-keto acid dehydrogenase complex (BCKAD), leading to a buildup of the branched-chain amino acids (leucine, isoleucine, and valine) and their toxic by-products (ketoacids) in the blood and urine.
MSUD occurs in approximately 1 in 86,800 to 185,000 live births [1,2]. The MSUD incidence is up to 1:200 live births in certain Mennonite populations in Pennsylvania and elsewhere due to a founder variant (c. 1312T>A) in the branched-chain ketoacid dehydrogenase complex gene (BCKDHA) [3].
Hyperglycemia and Diabetes
High blood sugar (hyperglycemia) is common in people with undiagnosed diabetes or poorly controlled diabetes. High levels of sugar (glucose) in the urine can make it smell sweet or like fruity cereal. 1 There are also other signs of high blood sugar, including: Excessive thirst.
Sweet-smelling urine may be a sign of uncontrolled diabetes or a rare disease of metabolism. Liver disease and certain metabolic disorders may cause musty-smelling urine. Some conditions that can cause changes in urine odor include: Bladder fistula.
Q: Why does my urine smell like maple syrup? A: If you notice a very distinct sweet smell as you urinate, this could mean one of two things: maple syrup urine disease or diabetic ketoacidosis (DKA). Maple syrup urine disease is a metabolic disorder that causes certain amino acids to build up in the body.