The relationship between dialysis adequacy and the rate of change in uric acid level by hemodialysis

Abstract

Aim: Although one of the commonly used methods for determining dialysis adequacy is the urea kinetic model, it is not the gold standard. Different parameters are needed to determine dialysis adequacy. In our study, we investigated the relationship between urea reduction rate (URR) and Kt/V which are used to assess dialysis adequacy and the rate of change in uric acid, a purine metabolite, by hemodialysis.

Methods: A total of 133 patients who had undergone hemodialysis treatment due to renal failure between March 2010 and September 2010 were evaluated retrospectively. Urea kinetic modeling was used to measure dialysis adequacy. The following formula was used to do this; Kt/V=-ln(R-0.008xT)+(4-3.5xR)xUF/W[R; postdialysis blood ureanitrogen (BUN)/predialysis BUN, T; duration of dialysis (hr), UF; total ultrafiltration during dialysis (L), W; patient weight after dialysis (kg)]. The urea reduction rate was calculated using the formula; URR(%)=100x(1-postdialysis BUN/predialysis BUN). Uric acid reduction rate (UARR) was calculated using the formula; UARR(%)=100x(1-Uric acid after/Uric acid before). The relationship between URR and Kt/V ratios which are used to assess dialysis adequacy and UARR is evaluated.

Results: Median urea, uric acid and creatinine reduction rates were 72%, 74% and 63.9%, respectively. There was a statistically significant correlation between reduction rates of uric acid, creatinine and urea after dialysis (p<0.001). There was a statistically significant relationship between URR and Kt/V which are used to assess dialysis adequacy,and UARR (p<0,001). According to the ROC analysis in our study, we defined UARR value that will demonstrate dialysis adequacy as at least 65.8% (sensitivity 97.9% and specificity 82.6%, area under the ROC curve=0.880, p<0.001).

Conclusion: A significant relationship was found between the URR and Kt/V ratios which are used to assess dialysis adequacy and UARR. We also determined in our study that the UARR value that shows dialysis adequacy should be at least 65.8%. To our knowledge, this is the first study to evaluate the relationship between UARR and dialysis adequacy. However, thefindings need to be confirmed by large, prospective, clinical trials.

Keywords

• Dialysis adequacy,Urea kinetic model,Kt/V,Uric acid

Hemodiyaliz ile ürik asit düzeyindeki değişim oranı ile diyaliz yeterliliği arasındaki ilişki

Öz

Amaç: Diyaliz yeterliliğini belirlemede sık kullanılan yöntemlerden biri üre kinetik modelleme olmasına rağmen altın standart değildir. Diyaliz yeterliliğinin belirlenmesinde farklı parametrelere ihtiyaç vardır. Biz çalışmamızda bir pürin metaboliti olan ürik asitin hemodiyaliz ile değişim oranına bakarak diyaliz yeterliliğini değerlendirmede kullanılan üre azalma oranı (URR) ve KT/V ile arasındaki ilişkiyi araştırdık.

Yöntemler: Çalışmamızda 2 merkezde Mart 2010 ile Eylül 2010 tarihleri arasında böbrek yetmezliği nedeniyle hemodiyaliz tedavisi gören toplam 133 hasta retrospektif olarak değerlendirildi. Diyaliz yeterliliğini ortaya koymak için üre kinetik modelleme kullanıldı. Bunun için Kt/V=–ln(R–0.008xt)+(4– 3.5xR)xUF/W([R=diyaliz sonrası kan üre azotu (BUN) / diyaliz öncesi BUN, t= diyaliz seansının süresi (saat), UF= diyalizde yapılan toplam ultrafiltrasyon (L), W= diyaliz sonrası hasta ağırlığı (kg)] formülü kullanıldı. ÜRR(%) = 100 x (1- BUNsonra / BUNönce) formülü kullanıldı. Ürik asit azalma oranı (UARR) (%) = 100 x (1- Ürik asit sonra / Ürik asit önce) formülü ile hesaplandı. UARR ile diyaliz yeterliliğini değerlendirmede kullanılan URR ve Kt/V oranları arasındaki ilişki değerlendirildi. 

Bulgular: Ortanca üre, ürik asit ve kreatinin azalma oranı sırası ile %72, %74, %63,9 olarak bulundu. Ürik asit, kreatinin ve ürenin diyaliz ile azalma oranları arasında istatistiksel olarak anlamlı korelasyon saptandı (p<0,001). UARR ile diyaliz yeterliliğini değerlendirmede kullanılan Kt/V ve URR arasında istatistiksel olarak anlamlı ilişki bulunmuştur (p<0,001). Çalışmamızda, ROC analizine göre, diyaliz yeterliliğini gösterecek UARR değerinin en az %65,8 (duyarlılık %97,9, özgüllük %82,6, ROC eğrisinin altındaki alan =0,880, p<0,001) olarak belirledik.

Sonuç: UARR ile diyaliz yeterliliğini değerlendirmede kullanılan URR ve Kt/V oranları arasında istatistiksel açıdan anlamlı ilişki tespit edildi. Ayrıca çalışmamızda diyaliz yeterliliğini gösterecek UARR değerinin en az %65,8 olması gerektiğini belirledik. Bizim bilgimize göre bu çalışma UARR ile diyaliz yeterliliği arasındaki ilişkiyi değerlendiren ilk çalışmadır. Fakat bu bulgunun büyük, prospektif, klinik çalışmalar ile teyit edilmeye ihtiyacı vardır.

Anahtar Kelimeler

• Diyaliz yeterliliği,Üre kinetik model,Kt/V,Ürik asit

Kaynakça

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