The usefulness of renal vein renin studies in hypertensive children: a 25-year experience

Abstract

Lateralised renin secretion predicts improvement following surgery/angioplasty of the affected kidney in paediatric hypertension. We retrospectively analysed all our renal vein renin (RVR) studies undertaken in hypertensive children and their subsequent clinical outcomes over a 25-year period. The outcomes were categorised as cure, improvement or no change in hypertension. The proportions that benefited by 'following' or 'ignoring' the RVR results in relation to the aetiology of hypertension and subsequent therapy were compared. A ratio between the RVR value of the dominant kidney and that of the contralateral kidney (R/Rc ratio) above 1.5 was considered to show significant lateralisation. A ratio between RVR value of the contralateral kidney and that of the caudal inferior vena cava (Rc/P ratio) of less than 1.3 was considered to indicate contralateral renin suppression. Of 233 RVR records, 137 were suitable for analysis. Of these, 39 had reflux nephropathy (RN), 73 renovascular disease (RVD) and the others miscellaneous conditions. Of the 39 hypertensive children with RN, the R/Rc ratio was over 1.5 in 20 subjects, of whom 11 underwent surgery. Amongst the 19 with an R/Rc less than 1.5, 4 also had surgery. Of the 73 hypertensive children with RVD, the R/Rc ratio was over 1.5 in 38 subjects, of whom 20 underwent surgery/angioplasty. Amongst the 35 with an R/Rc less than 1.5, 7 also underwent surgery/angioplasty. In RN there was no significant difference in the proportion that improved with allocated treatment, as suggested by the 'test' when compared with those who were 'misallocated'. In RVD, however, the proportion improved (35.0%) by 'following the test' (i.e. R/Rc ratio) was significantly greater than the proportion improved (12.5%) in the group in whom the test was 'ignored'. This was true for both R/Rc and Rc/P ratios. Thus, RVR measurements are useful for identifying hypertensive children with RVD that may have a favourable outcome after surgery, but this does not apply to children with RN. Measurements, however, may have diagnostic value even if surgery or angioplasty is not anticipated.