2
4
5
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W
X
Y
Z

Maple syrup urine disease
Definition:
Maple syrup in urine disease is an inheritable metabolic disease of amino acid metabolism characterized by acidosis, central nervous system symptoms, and urine that may smell sweet like maple syrup.

Alternative Names:
MSUD

Causes, incidence, and risk factors:

Maple syrup urine disease (MSUD) is caused by the inability to metabolize the so-called 'branched-chain' amino acids leucine, isoleucine, and valine. The disease is called MSUD because urine from affected people smells like maple syrup.

In the most severe form, MSUD causes severe acidosis during the first week of life. This is characterized by progressively poorer feeding, vomiting, seizures, lethargy, and finally coma.

Untreated infants may die in the first few weeks of life in severe forms of the disease. MSUD also occurs in an intermittent form and a mild form. Even in the mildest form, MSUD results in mental retardation and bouts of acidosis precipitated by stresses such as ordinary infections.
Symptoms:
  • Family history of MSUD or unexplained infant death
  • Urine which smells like maple syrup
  • Feeding difficulties
  • Lethargy
  • Vomiting
  • Seizures
  • Coma
  • Avoiding food/feeding intolerance
Signs and tests:
  • Urine amino acids (elevated levels of the amino acids leucine, isoleucine, and valine)
  • Plasma amino acids (elevated levels of leucine, isoleucine, and valine)
  • Ketosis = elevated leves of ketone bodies in urine and plasma
  • Acidosis = excess acid in blood
Treatment:
Treatment of the acute episode:
  • Acute acidosis is treated to restore normal pH.
  • Stop protein in diet as this is a protein intolerance disease.
  • High levels of intravenous fluid, sugar and fat are important to prevent dehydration and provide energy to stimulate protein synthesis which lowers the levels of the amino acids which cannot be broken down.
  • Peritoneal dialysis can be used to remove the high levels of amino acids.
  • Prompt institution of a special diet that is free of branch chain amino acids.

Long range treatment:
Treatment includes a special diet. Strict compliance is necessary to prevent neurological damage. This requires close supervision by a registered dietitian or physician, and cooperation by parent(s). The diet includes a synthetic infant formula with low levels of the amino acids leucine, isoleucine, and valine.

Frequent blood testing of amino acids allows doctors/dieticians to adjust the balance of these branch chain amino acids so that they are neither deficient nor in excess. Affected people must remain on this diet permanently.
Expectations (prognosis):
If left untreated, life-threatening neurological damage may result. Despite dietary treatment, stressful situations can still precipitate bouts of acidosis and death may occur during these episodes. With strict dietary treatment, children have grown up healthy and able to attend college.
Complications:
  • Neurological damage, for example lower IQ if poorly treated
  • Acidosis episodes (may be fatal)
Calling your health care provider:
Call your health care provider if you have a family history of MSUD and are contemplating starting a family. Also call immediately if you have a newborn who exhibits symptoms suggestive of maple syrup urine disease.
Prevention:
Genetic counseling is suggested for prospective parents with a family history of maple syrup urine disease. Some states, such as Pennsylvania, screen all newborn babies blood for signs of MSUD. You may receive a call from your pediatrician stating that your baby had an abnormal blood test for MSUD. This may be a 'false positive' test, but a blood test (amino acid levels) should be done right away to tell for certain.
Review Date: 8/6/2001
Reviewed By: David G. Brooks, M.D., Ph.D., Division of Medical Genetics, University of Pennsylvania Medical Center, Philadelphia, PA. Review provided by VeriMed Healthcare Network.
A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org). URAC's accreditation program is the first of its kind, requiring compliance with 53 standards of quality and accountability, verified by independent audit. A.D.A.M. is among the first to achieve this important distinction for online health information and services. A.D.A.M. is also a founding member of Hi-Ethics (www.hiethics.com) and subscribes to the principles of the Health on the Net Foundation (www.hon.ch).

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. Copyright 2003 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.
adam.com