Study of ischemia modified albumin (IMA) as a biomarker in hypertensive retinopathy
Background. Hypertension (HTN) is one of the leading causes of morbidity and mortality worldwide. A prompt diagnosis and treatment of hypertensive retinopathy (HR), the leading complication of HTN is pivotal for a better visual outcome. Increased blood pressure on its own cannot fully clarify the development of retinal alterations, therefore an additional pathogenetic mechanism, such as oxidative stress, might be inquired.
The aim of the study was to evaluate the changes in the level of ischemia modified albumin (IMA) in the serum and tears of HR patients in order to establish the predictive value of IMA for the HR progression.
Methods. Serum and tear samples for the measurement of IMA were collected from 90 patients detected primarily with HR, who were not taking any antihypertensive or other drug that could influence the results of the study, divided according to the Keith-Wagener classification into GI ‒ 36 patients with HR grade I, GII ‒ 35 with HR grade II and GIII ‒ 19 with HR grade III. Serum and tear IMA levels were assessed using the Co2+ binding method (Gudumac V. et al., 2009) and expressed as median and interquartile range. Kruskal-Wallis and Mann-Whitney nonparametric tests were used to compare the groups and the Spearman correlation coefficient was calculated (SPSS 23.0), with p<0.05 being statistically significant.
Results. The groups showed a statistically significant difference in serum IMA (p=0.006), the values increasing in parallel with the progression of HR. The serum IMA level in GII increased compared to GI (+3%; 239.06 µM/L (IQR 75.58) vs 231.77 µM/L (IQR 104.09), p=1.00), as well as in GIII patients compared to GII (+17%; 277.67 µM/L (IQR 88.72) vs 239.06 µM/L (IQR 75.58), p=0.04). There were no differences in IMA content (p=0.160), between groups in the tears. No correlations were found between serum and tear IMA levels (p=0.134), but serum IMA showed a significant moderate strength, positive correlation with the degree of HR (r=0.307**, p=0.003).
Conclusion. A progressive enhancement in serum IMA level as HR advanced was identified. Thereby, the results suggest the potential relevance of serum IMA as a sensitive and early biomarker useful for grading and optimal treatment of the patients with HR.