The disease is estimated to affect 1 out of 185,000 infants worldwide and its frequency increases with certain heritages.Newborn screening for maple syrup urine disease involves analyzing the blood of 1–2 day-old newborns through tandem mass spectrometry. The blood concentration of leucine and isoleucine is measured relative to other amino acids to determine if the newborn has a high level of branched-chain amino acids. Once the newborn is 2–3 days old the blood concentration of branched-chain amino acids like leucine is greater than 1000 μmol/L and alternative screening methods are used. Instead, the newborns urine is analyzed for levels of branched-chain alpha-hydroxyacids and alpha-ketoacids.The amount and type of enzyme activity in an affected individual with MSUD will determine which classification the affected individual will identify with:
Classic MSUD: Less than 2% of normal enzyme activity
Intermediate MSUD: 3-8% normal enzyme activity
Intermittent MSUD: 8-15% of normal enzyme activity
Thiamine-Responsive MSUD: Large doses of thiamine will increase enzyme activity. Classification
Maple syrup urine disease can be classified by its pattern of signs and symptoms, or by its genetic cause. The most common and severe form of this disease is the classic type, which appears soon after birth, and as long as it remains untreated, gives rise to progressive and unremitting symptoms.
Orthostatic proteinuria (synonyms: orthostatic albuminuria, postural proteinuria)  is a benign condition. A change in renal hemodynamics, which in some otherwise normal individuals, causes protein (mostly albumin) to appear in urine when they are in the standing position. Urine formed when these individuals are lying down is protein-free.There is normal urinary protein excretion during the night but increased excretion during the day, associated with activity and upright posture. Total urinary protein excretion may be increased but levels above 1 g per 24 hours are more likely to be associated with underlying renal disease. The exact cause for orthostatic proteinuria is not known. == References ==