"Serum and urinary angiotensinogen levels as prognostic indicators in acute kidney injury: a prospective study"

Dear Editor,

We read with interest the article by Akin et al., who found that urinary angiotensinogen levels (corrected by urinary creatinine) can serve as an indicator of the severity of acute kidney injury (AKI)¹. It is well known that AKI is a common and serious complication in hospitalized patients. Kellum et al. reported that AKI may develop in 18% of general hospitalized patients and half of ICU patients². Currently, the diagnosis of AKI still relies on elevated serum creatinine levels, but its sensitivity is relatively poor. This study found that urinary angiotensinogen level has a high value in the prognosis and management of AKI patients. We congratulate the authors for their valuable contributions, but we still raise some concerns that should be discussed.

First, this study lacks a group of healthy controls. Although the study included 79 AKI patients at different stages, the data are still insufficient, because the expression of angiotensinogen in healthy controls is unclear. Specifically, it is not known whether there is a difference between angiotensinogen levels between healthy individuals and AKI patients in the early stages. Therefore, it is recommended to include a group of healthy controls to further elucidate the trends in angiotensinogen changes.

Second, in this study, the primary cause of AKI was cerebrovascular damage, accounting for 25% of cases. However, the most common cause of AKI is sepsis, followed by major surgery³. There is a close relationship between the renin-angiotensin-aldosterone system (RAAS) and cerebrovascular diseases, with RAAS being activated in patients with cerebrovascular disease⁴. This may lead to bias. It is recommended to include more AKI patients induced by sepsis and major surgery.

Third, according to the KDIGO AKI staging, the severity of AKI increases with a higher stage. However, in this study, the authors found that the uAGT/uCr ratio was significantly lower in AKI stage 2 (5.03±5.04) compared to AKI stage 1 (9.93±10.82), but it was significantly higher in AKI stage 3 (32.15±37.13) compared to AKI stage 2 (5.03±5.04). Could this be related to the fact that urine output in AKI stage 3 is significantly reduced compared to stages 1 and 2? If the authors could elaborate on this issue in the discussion, it would make the study more rigorous.

• Funding:

  none.

REFERENCES

• ¹
  Akin A, Demir AK, Özmen ZC. Serum and urinary angiotensinogen levels as prognostic indicators in acute kidney injury: a prospective study. Rev Assoc Med Bras (1992). 2023;69(12):e20230716. https://doi.org/10.1590/1806-9282.20230716
  » https://doi.org/10.1590/1806-9282.20230716
• ²
  Kellum JA, Romagnani P, Ashuntantang G, Ronco C, Zarbock A, Anders HJ. Acute kidney injury. Nat Rev Dis Primers. 2021;7(1):52. https://doi.org/10.1038/s41572-021-00284-z
  » https://doi.org/10.1038/s41572-021-00284-z
• ³
  Uchino S, Kellum JA, Bellomo R, Doig GS, Morimatsu H, Morgera S, et al. Acute renal failure in critically ill patients: a multinational, multicenter study. JAMA. 2005;294(7):813-8. https://doi.org/10.1001/jama.294.7.813
  » https://doi.org/10.1001/jama.294.7.813
• ⁴
  Li W, Li SG, Li L, Yang LJ, Li ZS, Li X, et al. Soyasaponin I alleviates hypertensive intracerebral hemorrhage by inhibiting the renin-angiotensin-aldosterone system. Clin Exp Hypertens. 2023;45(1):2177667. https://doi.org/10.1080/10641963.2023.2177667
  » https://doi.org/10.1080/10641963.2023.2177667

Publication Dates

• Publication in this collection
  11 Nov 2024
• Date of issue
  2024

History

• Received
  05 July 2024
• Accepted
  09 July 2024