**4. Conclusion**

The implementation of bioimpedance measurements to assist in the optimisation of the patient's target weight, and the use of salt restriction to avoid excessive fluid gains, should enable most haemodialysis patients to stay close to normal hydration throughout the interdialytic period.

Future research in the use of bioimpedance will include verification of the BCM models in patients at the extremes of body composition and with conditions leading to very abnormal fluid distribution and the effect of transcellular fluid shifts caused by changes in electrolyte levels. Simple, inexpensive devices to allow patients to track changes in their fluid status should be developed. The effect of varying the target time-averaged hydration status on morbidity and mortality should be studied so that volume control can become a measure of dialysis adequacy as suggested by Ok and Mees (Ok & Mees, 2010).

For the majority of patients, interdialytic fluid gain can be controlled by using a standard low-normal dialysate sodium and keeping salt consumption to no more than 6 g/day. Staff will also benefit from keeping to this recommended salt intake. Patients who tolerate ultrafiltration very poorly will need careful management of sodium loading on dialysis together with a customised low-salt diet. An individualised approach, including improved diabetic control and motivational interviewing will also be required for patients with very low pre-dialysis serum sodium levels whose fluid intake does not depend on salt.

#### **5. References**


guide, every kilogram gained between dialysis sessions corresponds to an intake of 8 g of salt. So a 0.5 kg decrease in IDWG over the short break shows they have managed to reduce their salt intake by 4 g (2 g/day). Staff will need to carry out 24 hour urine collections to

The link between low IDFG and poor survival is well established (Sezer et al, 2002) and haemodialysis patients are often at risk of malnutrition, so it is essential to ensure that what appears to be a successful intervention to reduce salt intake does not lead to undiagnosed

The implementation of bioimpedance measurements to assist in the optimisation of the patient's target weight, and the use of salt restriction to avoid excessive fluid gains, should enable most haemodialysis patients to stay close to normal hydration throughout the

Future research in the use of bioimpedance will include verification of the BCM models in patients at the extremes of body composition and with conditions leading to very abnormal fluid distribution and the effect of transcellular fluid shifts caused by changes in electrolyte levels. Simple, inexpensive devices to allow patients to track changes in their fluid status should be developed. The effect of varying the target time-averaged hydration status on morbidity and mortality should be studied so that volume control can become a measure of

For the majority of patients, interdialytic fluid gain can be controlled by using a standard low-normal dialysate sodium and keeping salt consumption to no more than 6 g/day. Staff will also benefit from keeping to this recommended salt intake. Patients who tolerate ultrafiltration very poorly will need careful management of sodium loading on dialysis together with a customised low-salt diet. An individualised approach, including improved diabetic control and motivational interviewing will also be required for patients with very

Brener ZZ, Kotanko P, Thijssen S, Winchester JF & Bergman M. (2010) Clinical benefit of

Chamney PW, Wabel P, Moissl UM, Müller MJ, Bosy-Westphal A, Korth O, Fuller NJ. (2007)

Charra B. (2007) Fluid balance, dry weight, and blood pressure in dialysis. *Hemodial Int,* Vol.

Davita. The hemodialysis diet. http://www.davita.com/kidney-disease/diet-andnutrition/diet-basics/the-hemodialysis-diet/e/5314 (accessed May 2011). de Paula FM, Peixoto AJ, Pinto LV, Dorigo D, Patricio PJ & Santos SF. (2004) Clinical

Gardiner C, Scott H, Wright M, Greaves E & Lindley E. (2006) IDWG, salt and water – an

preserving residual renal function in dialysis patients: an update for clinicians. *Am* 

A whole-body model to distinguish excess fluid from the hydration of major body

consequences of an individualized dialysate sodium prescription in hemodialysis

audit of dialysis staff. British Journal of Renal Medicine, Vol. 11 No. 3 (2006), pp.

low pre-dialysis serum sodium levels whose fluid intake does not depend on salt.

dialysis adequacy as suggested by Ok and Mees (Ok & Mees, 2010).

*J Med Sci.*, Vol. 339 (2010), pp. 453-6.

11 (2007), 21-31.

12-14.

tissues. *Am J Clin Nutr* Vol. 85 (2007), pp. 80–89.

patients. *Kidney Int,* Vol. 66 (2004), pp. 1232-1238.

check their own salt consumption.

weight loss and fluid overload.

**4. Conclusion** 

interdialytic period.

**5. References** 


**12** 

*Czech Republic* 

**Cell-Free Nucleic Acids as Biomarkers of** 

In this review we describe what is recently known about the origin of free nucleic acids in human circulation, which processes can cause the elevations of their total concentrations and the alterations in the ratios among different types of circulating nucleic acids in human plasma and serum. We focus on the inflammatory response and apoptosis with regard to changes in the quantity and quality of circulating nucleic acids pool. We discuss the use of cell-free nucleic acids as biomarkers in patients with renal failure not only in hemodialysis but also in peritoneal dialysis with regard to future perspectives on the field of cell-free nucleic acids.

The phenomenon of cell-free DNA circulating in human plasma was discovered in 1948 (Mandel &, Metais, 1948,). The authors detected DNA and RNA in blood plasma of healthy control and patients. With regard to the lack of biological understanding of such a finding their work remained unnoticed. During next thirty years only two studies focusing on cellfree DNA appeared. The patients with lupus erythematosus (Tan et al., 1966, in Swarup & Rajeswari, 2007) and the patients with rheumatoid arthritis (Ayala et al., 1951) were studied and elevated levels DNA in circulation were reported. The medical importance of cell-free nucleic acids was recognized when the decreasing levels of these nucleic acids were

In 1994, mutated oncogene K-ras was discovered in the pool of circulating DNA in pancreatic cancer patients (Sorenson at al., 1994). In 1997 the circulating DNA of fetal origin was found in plasmas of pregnant women (Lo et al., 1997). Till today numerous studies were performed not only to understand the nature and biological meaning of cell-free DNAs and RNAs but mainly to establish their diagnostic use under different clinical conditions such as cancer, autoimmune

Although recent molecular biology and genetics employ very broad spectrum of sophisticated methods, the complete understanding of biology of cell-free nucleic acids was so far not achieved. As there are speculations concerning the regulatory function of circulating nucleic acids in plasma, the clinical laboratory research and practice stream to develop approaches allowing the analytic use of these molecules. The main sources of nucleic acids in plasma are necrosis, apoptosis and active release by living, non-apoptotic cells. All mentioned processes will be discussed in details in following sections. Cell-free

**2. Origin and clearance of free nucleic acids in human circulation** 

reported in cancer patients after successful chemotherapy (Leon et al., 1977).

disorders, pregnancy related disorders and trauma (for review Tong & Lo, 2006).

**1. Introduction** 

**Biocompatibility in Dialytic Process** 

Marie Korabečná1 and Aleš Hořínek2

*First School of Medicine, Charles University in Prague* 

