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Commentary

Neurodegener Dis DOI: 10.1159/000345414

Homocysteine and Vitamin B 12 LevelsRelated to MRI White Matter Abnormalities in Parkinson’s Disease Dementia

Omer Ozcan a Alpaslan Cosar b

a Department of Clinical Biochemistry, GATA Haydarpasa Training Hospital, Istanbul , and b Laboratory of Biochemistry,Van Military Hospital, Van , Turkey

son’s disease group. This finding could also be further analyzed by using the ROC curve which allows the deter-mination of a cutoff point, and sensitivity and specificity values. Additionally, the percentage of patients with vita-min B 12 levels below the reference range was 5.3 and 14% in the Parkinson’s disease and PDD groups. The signifi-cantly lower vitamin B 12 levels in the PDD group should also be further evaluated by using urine or serum meth-ylmalonic acid concentrations, which is accepted as a gold standard test for the assessment of functional or tis-sue levels of vitamin B 12 deficiency [3] . After all, this timely report draws our attention to the importance of these micronutrients for PDD patients.

We read with great interest an investigation by Slawek et al. [1] on the total homocysteine (tHcy) levels and some vascular risk factors in relation to the white matter chang-es of Parkinson’s disease dementia (PDD). We congratu-late the authors on their valuable article. It is not so easy to collect a great number of samples from PDD patients and make precise assessments. However, we would like to add a short note to help the readers to interpret the results of the study.

In the study, the mean tHcy levels of patients and con-trols were found to be 17.75 8 7.86 and 13.6 8 7.39 � mol/l, respectively. Although the authors accepted these values as being below the upper limit of their laboratory’s normative values (upper limit defined as 20.44 � mol/l for females and 16.00 � mol/l for males), the widely accepted upper limit for plasma tHcy levels is 12 � mol/l, which is far below their values. Furthermore, the manufacturer of the tHcy determination kit they used also recommends the lower values. Thus, the increased tHcy levels in the patient and control groups should be clarified. One rea-son for elevated tHcy concentrations might be due to pro-longed waiting times of samples at room temperaturebefore centrifugation, which has been reported to cause abnormally increased tHcy measurements [2] . Although they did not find any relationship between tHcy and white matter abnormalities, higher tHcy levels were found in patients with PDD compared with the Parkin-

Received: August 14, 2012 Accepted: September 27, 2012 Published online: December 12, 2012 D i s e a s e s

Omer Ozcan, MD, PhD Department of Clinical Biochemistry GATA Haydarpasa Training Hospital, Uskudar TR–34660 Istanbul (Turkey) E-Mail ozcanmd   @   yahoo.com

© 2012 S. Karger AG, Basel1660–2854/12/0000–0000$38.00/0

Accessible online at:www.karger.com/ndd

References 1 Slawek J, Roszmann A, Robowski P, et al: The impact of MRI white matter hyperintensities on dementia in Parkinson’s disease in rela-tion to the homocysteine level and other vas-cular risk factors. Neurodegener Dis 2012, DOI 10.1159/000338610.

2 Hill DM, Johnson LJ, Burns PJ, et al: Effects of temperature on stability of blood homo-cysteine in collection tubes containing 3- deazaadenosine. Clin Chem 2002; 48: 2017–2022.

3 Norman EJ: Urinary methylmalonic acid/creatinine ratio defines true tissue cobala-min deficiency. Br J Haematol 1998; 100: 614–615.

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