Table 1.

Cardinal Biochemical Findings that Establish the Diagnosis of Homocystinuria

AnalyteSpecimenExpected Findings
Neonate with
homocystinuria		Untreated older person with
homocystinuria		Control
Total homocysteine 1 (tHcy)Plasma 250 to >100 µmol/L>100 µmol/L<15 µmol/L
Methionine (on amino acid analysis)Plasma200-1500 µmol/L
(3-23 mg/dL)		>50 µmol/L
(>0.7 mg/dL)		10-40 µmol/L
(0.2-0.6 mg/dL)
1.

Click here (pdf) for terms used to describe sulfur amino acids.

2.

Plasma tHcy measurement is an effective method for assuring accurate diagnosis of homocystinuria. Even after a week of storage without deproteinization, virtually all tHcy can still be recovered by a method of preparation that includes a reducing agent such as dithiothreitol [Smith et al 1998].

From: Homocystinuria Caused by Cystathionine Beta-Synthase Deficiency

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