Depressed cerebral oxygen metabolism in patients with chronic renal failure: a positron emission tomography study

To elucidate brain oxygen metabolism in uremic patients, regional cerebral blood flow (rCBF), oxygen extraction (rOEF), and oxygen metabolism (rCMRO(2)) were measured by positron emission tomography (PET) in 10 hemodialysis (HD) patients and 13 predialysis patients with chronic renal failure (CRF). Data were compared with 20 nonuremic patients (controls) without neurological abnormalities, congestive heart failure, history of cerebrovascular accident, diabetes mellitus, or symptomatic brain lesion on magnetic resonance imaging. In the hemisphere, rCMRO(2) in both HD (1.82 +/- 0.10 mL/min/100 g) and CRF patients (1.95 +/- 0.09 mL/min/100 g) showed significantly lower values compared with controls (2.23 +/- 0.05 mL/min/100 g; P < 0.01). Hemispheric rCBF in HD (35.6 +/- 2.1 mL/100 g/min) and CRF patients (36.1 +/- 2.1 mL/100 g/min) was not different from controls (31.8 +/- 1.4 mL/100 g/min). Hemispheric rOEF in CRF patients (45.7% +/- 1.6%) was significantly greater than that in controls (40.5% +/- 1.2%; P < 0.02), but rOEF in HD patients (43.7% +/- 1.9%) did not increase significantly. These tendencies were similar in all regions of interest, especially cerebral cortices. All PET parameters in frontal cortices tended to show the lowest values in patients with renal failure. For all HD patients, rCBF in both the frontal cortex and white matter correlated inversely with HD therapy duration (P < 0.05). In conclusion, brain oxygen metabolism is depressed in patients with renal failure on or before the start of HD therapy. The cause for depressed brain oxygen metabolism is considered to be either dysregulation of cerebral circulation or lower brain cell activity.