NANP Board Practice Exam

In the context of Parkinson's and Alzheimer's disease, the presence of elevated levels of cysteine in urine is significant. Cysteine is an amino acid that has been studied for its role in the body's antioxidant defense system and its potential involvement in neurodegenerative processes. Research suggests that alterations in the metabolism of sulfur-containing amino acids, including cysteine, may be associated with the pathophysiology of these neurodegenerative conditions.

In comparison, while glucose might be elevated in certain metabolic conditions, it is not characteristically associated with Parkinson's or Alzheimer's. Protein levels in urine can indicate various health issues, but they aren't specific markers for these diseases. Sulfate levels are more related to sulfur metabolism but do not have the same recognized association with these neurodegenerative disorders as cysteine does. Thus, the correct answer is grounded in the biological significance of cysteine in relation to these specific diseases.