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

Abstract

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.