Publication
Urinary congophilia in women with hypertensive disorders of pregnancy and preexisting proteinuria or hypertension
Publisher:
Elsevier BV
Date:
10-2016
DOI:
10.1016/J.AJOG.2016.04.041
Abstract: Congophilia indicates the presence of amyloid protein, which is an aggregate of misfolded proteins, that is implicated in the pathophysiologic condition of preecl sia. Recently, urinary congophilia has been proposed as a test for the diagnosis and prediction of preecl sia. The purpose of this study was to determine whether urine congophilia is present in a cohort of women with preecl sia and in pregnant and nonpregnant women with renal disease. With the use of a preecl sia, chronic hypertension, renal disease, and systemic lupus erythematosus cohort, we analyzed urine s les from healthy pregnant control subjects (n = 31) and pregnant women with preecl sia (n = 23), gestational hypertension (n = 10), chronic hypertension (n = 14), chronic kidney disease n = 28), chronic kidney disease with superimposed preecl sia (n = 5), and chronic hypertension and superimposed preecl sia (n = 12). S les from nonpregnant control subjects (n = 10) and nonpregnant women with either systemic lupus erythematosus with (n = 25) and without (n = 14) lupus nephritis were analyzed. For each s le, protein concentration was standardized before it was mixed with Congo Red, spotted to nitrocellulose membrane, and rinsed with methanol. The optical density of the residual Congo Red stain was determined Congo red stain retention was calculated, and groups were compared with the use of the Mann-Whitney test or Kruskal-Wallis analysis of Variance test, as appropriate. Congophilia was increased in urine from women with preecl sia (median Congo red stain retention, 47% interquartile range, 22-68%) compared with healthy pregnant control subjects (Congo red stain retention: 16% interquartile range, 13-21% P = .002), women with gestational hypertension (Congo red stain retention, 20% interquartile range, 13-27% P = .008), or women with chronic hypertension (Congo red stain retention, 17% interquartile range, 12-28% P = .01). There were no differences in Congo red retention between pregnant women with chronic hypertension and normal pregnant control subjects (Congo red stain retention, 17% [interquartile range, 12-28%] vs 16% [interquartile range, 13-21%], respectively P = .72). Congophilia was present in pregnant women with chronic kidney disease (Congo red stain retention, 32% interquartile range, 14-57%), being similar to values found in women with preecl sia (P = .22) and for women with chronic kidney disease and superimposed preecl sia (Congo red stain retention, 57% [interquartile range, 29-71% P = .18). Nonpregnant women with lupus nephritis had higher congophilia levels compared with nonpregnant female control subjects (Congo red stain retention, 38% [interquartile range, 17-73%] vs 9% [7-11%], respectively P < .001) and nonpregnant women with systemic lupus erythematosus without nephritis (Congo red stain retention, 38% [interquartile range, 17-73%] vs 13% [interquartile range, 11-17%], respectively P = .001). A significant positive correlation was observed between congophilia and protein:creatinine ratio (Spearman rank correlations, 0.702 95% confidence interval, 0.618-0.770 P < .001). This study confirms that women with preecl sia and chronic kidney disease without preecl sia have elevated urine congophilia levels compared with healthy pregnant women. Nonpregnant women with lupus nephritis also have elevated urine congophilia levels compared with healthy control subjects. An elevated Congo Red stain retention may not be able to differentiate between these conditions further research is required to explore the use of congophilia in clinical practice.