Proteinuria and nocturnal blood pressure dipping in hypertensive children and adolescents

Abstract

Background: The absence of nocturnal blood pressure dipping is associated with adverse cardiovascular outcomes in adults, and proteinuria is a risk factor for non-dipping in this population. Risk factors for non-dipping in children are largely unknown.

Methods: We retrospectively identified patients aged 5-19 years who underwent 24-h ambulatory blood pressure monitoring (ABPM) from August 2018 to January 2019 and had a spot urine protein-to-creatinine ratio (PCR) within 1 year of their ABPM. Dipping was defined as ≥10% reduction in systolic and diastolic blood pressure from day to night. Multivariable logistic and linear regression models evaluated the association of proteinuria with non-dipping.

Results: Among 77 children identified, 27 (35.1%) were non-dippers. Each two-fold higher urine PCR was associated with 38% higher odds of non-dipping, after adjusting for body mass index (BMI). Higher urine PCR was also associated with a lower diastolic dipping percentage by 1.33 (95% confidence interval 0.31-2.34), after adjusting for BMI, age, and estimated glomerular filtration rate.

Conclusions: Limitations of this study include its retrospective design and the time lapse between urine PCR and ABPM. Proteinuria appears to be associated with blood pressure non-dipping in children. This finding needs to be confirmed in prospective studies.

Impact: Our study demonstrates the association of proteinuria with non-dipping of blood pressure in children. This association has been explored in adults, but to our knowledge, this is the first time it is evaluated in children referred for evaluation of elevated blood pressure. Non-dipping is a modifiable risk factor for kidney function decline and cardiovascular disease in adulthood, and thus early identification in children is important. The association between proteinuria and non-dipping in children will allow us to more readily identify those at risk, with a future focus on interventions to modify blood pressure dipping patterns.

Figure 1.

A total of 214 ABPMs were completed between August 2018 and January 2019, of which 213 were first-time ABPMs. One subject had Lowe Syndrome and was excluded. Twenty ABPMs were of inadequate quality to be interpretable. Of the remaining 192, seventy-seven had a urine protein or urine microalbumin test and were included in the study.

Figure 2.

The distribution of log₂(urine protein/creatinine) in dippers (blue) and non-dippers (red).

Figure 3.

Grouped scatterplot of the correlation between diastolic dipping percentage and log₂(urine protein/creatinine) shown in blue, and systolic dipping percentage and log₂(urine protein/creatinine) shown in red.