Validation of serum transthyretin (prealbumin) as a nutritional parameter in hemodialysis patients.

OBJECTIVE

To evaluate the use of serum transthyretin (TTR) as a valid indicator of nutritional status in the hemodialysis patient and to validate the correlation of low-serum (TTR) levels with established nutrition assessment parameters.

DESIGN

Prospective, cohort, correlation analysis.

SETTING

Free-standing outpatient dialysis center.

PATIENTS

Fifty-one stable, chronic hemodialysis patients meeting the following selection criteria: (1) received thrice weekly hemodialysis treatments for greater than 3 months, (2) absence of impaired hepatic function, (3) absence of chronic infection, inflammatory syndromes, or infections in the 3 months before the study, (4) not taking corticosteroids, and (5) willing to participate in the study as evidenced by signing of an informed consent.

INTERVENTION

Serum TTR, albumin, blood urea nitrogen, creatinine, cholesterol, postdialysis weight and body mass index were measured monthly for 6 consecutive months. Normalized protein catabolic rate and KT/V were measured monthly for 3 consecutive months.

MAIN OUTCOME MEASURES

Nutrition and biochemical indices.

RESULTS

The overall mean TTR level was 32 mg/dL +/- 7 for the 6-month study period. Thirty-six percent of patients had mean TTR levels less than 30 mg/dL. TTR levels less than 30 mg/dL correlated significantly with urine outputs greater than 240 mL/24 hours, predialysis blood urea nitrogen < 18 mmol/L (<50 mg/dL), and normalized protein catabolic rate less than 0.8 g/kg/d (P < .05). A significant correlation was found between TTR and creatinine, albumin and loss of dry body weight (P < .05). Mean TTR levels less than 30 mg/dL were found in 33% of subjects with mean albumin levels greater than 35 g/L (>3.5 g/dL) and in 19% with mean albumin levels greater than 40 g/L (>4.0 g/dL). TTR levels were consistently lower in diabetics for all 6 months (statistically significant in 2 out of 6 months).

CONCLUSION

Measuring serial serum TTR levels in hemodialysis patients is a reliable method for identifying patients in need of nutrition intervention.