Cystatin C proteoforms in chronic kidney disease.

Cystatin C, a cysteine protease inhibitor, is used as a biomarker of renal function. It offers several advantages compared to creatinine, and formulas for the estimation of the glomerular filtration rate based on cystatin C have been developed. Recently, several proteoforms of cystatin C have been discovered, including an intact protein with a hydroxylated proline at the N-terminus, and N-terminal truncated forms. There is little knowledge about the biological significance of these proteoforms. METHODS: Cross-sectional study of patients with different stages of chronic renal disease (pre-dialysis n = 53; hemodialysis n = 51, renal transplant n = 53). Measurement of cystatin C proteoforms by MALDI-TOF MS, assessment of medicine prescription using the first two levels of the Anatomical Therapeutic chemical system from patients' records. RESULTS: Patients receiving hemodialysis had the highest cystatin C concentrations, followed by pre-dialysis patients and patients with a renal transplant. In all groups, the most common proteoforms were native cystatin C and CysC 3Pro-OH while the truncated forms made up 28%. The distribution of the different proteoforms was largely independent of renal function and total cystatin C. However, the use of corticosteroids (ATC-L02) and immunosuppressants (ATC-H04) considerably impacted the distribution of proteoforms. CONCLUSION: The different proteoforms of cystatin C increased proportionally with total cystatin C in patients with chronic kidney disease. Prescription of corticosteroids and immunosuppressants had a significant effect on the distribution of proteoforms. The biological significance of these proteoforms remains to be determined.

Factors associated with nutritional risk in patients receiving haemodialysis assessed by Nutritional Risk Screening 2002 (NRS2002).

BACKGROUND: Nutritional Risk Screening 2002 is recommended as a screening tool to identify patients at risk of undernutrition for all patients in hospitals by the European Society of Clinical Nutrition and Metabolism. Nutritional risk is associated with increased morbidity and mortality in patients, and it is common among patients on haemodialysis. Factors associated with nutritional risk that could facilitate the screening/diagnostic procedures are warranted. OBJECTIVES: Identification of factors that are associated with nutritional risk in patients with end-stage renal disease treated with haemodialysis. DESIGN AND PARTICIPANTS: Single-centre, cross-sectional study in patients receiving haemodialysis (n = 53) were screened for nutritional risk using Nutritional Risk Screening 2002. Associations were made with data on dietary intake by 24-h dietary recall, and measurement of body composition, anthropometric measurements and biochemical variables. RESULTS: Nutritional risk was common among patients on haemodialysis (26%), and was associated with low energy and protein intake, and low pre-albumin concentrations also after adjustments for age and sex. Nutritional risk was neither associated with diabetes nor duration of dialysis treatment. CONCLUSION: Measurement of pre-albumin and dietary assessment using a 24-h dietary recall can support the identification of patients receiving haemodialysis at nutritional risk.