# A Prospective Observational Study: Are There Any Relationships Between Erythrocytosis, Renal Tubular–Glomerular Functions, and Systemic Hypertension in Adolescent Male Idiopathic Erythrocytosis Patients?

## TL;DR

Adolescent males with idiopathic erythrocytosis show higher blood pressure load despite normal average blood pressure, suggesting a link between high hematocrit and early blood pressure regulation issues.

## Contribution

This study identifies a novel association between elevated hematocrit in idiopathic erythrocytosis and increased ambulatory blood pressure load in adolescents.

## Key findings

- Adolescents with idiopathic erythrocytosis had higher systolic and diastolic blood pressure load values compared to healthy controls.
- Hematocrit levels were independently associated with 24-hour systolic blood pressure load after adjusting for age, BMI, and serum creatinine.
- Renal tubular and glomerular function parameters were similar between the groups.

## Abstract

What are the main findings?
Adolescent males with idiopathic erythrocytosis demonstrated higher ambulatory systolic and diastolic blood pressure load values when compared with healthy controls, despite similar mean blood pressure levels.Hematocrit levels were positively associated with several ambulatory blood pressure load parameters and remained independently associated with 24 h systolic blood pressure load in the multivariable regression analysis.

Adolescent males with idiopathic erythrocytosis demonstrated higher ambulatory systolic and diastolic blood pressure load values when compared with healthy controls, despite similar mean blood pressure levels.

Hematocrit levels were positively associated with several ambulatory blood pressure load parameters and remained independently associated with 24 h systolic blood pressure load in the multivariable regression analysis.

What are the implications of the main findings?
Elevated hematocrit levels in adolescents with idiopathic erythrocytosis may contribute to early alterations in blood pressure regulation.These findings suggest that adolescents with idiopathic erythrocytosis may benefit from closer blood pressure monitoring to detect potential cardiovascular risk at an early stage.

Elevated hematocrit levels in adolescents with idiopathic erythrocytosis may contribute to early alterations in blood pressure regulation.

These findings suggest that adolescents with idiopathic erythrocytosis may benefit from closer blood pressure monitoring to detect potential cardiovascular risk at an early stage.

Background: Childhood hypertension is an important predictor of adult cardiovascular disease. Idiopathic erythrocytosis in adolescent males is characterized by elevated hemoglobin and hematocrit levels, which may increase blood viscosity and potentially influence blood pressure (BP) regulation. However, the relationships between erythrocytosis, renal tubular–glomerular function, and systemic hypertension in adolescents remain unclear. Methods: This prospective observational case–control study was conducted between October of 2023 and April of 2024, including 37 male adolescents with idiopathic erythrocytosis and 24 age-matched healthy male controls. Complete blood count parameters were confirmed using two samples obtained at separate time points. Biochemical, urinalysis, tubular phosphorus reabsorption, and fractional excretion of sodium tests were performed to assess renal tubular and glomerular function, and 24 h ambulatory blood pressure monitoring (ABPM) was performed in all participants and interpreted according to the 2022 American Heart Association recommendations. Results: The mean systolic and diastolic BP values measured via ABPM did not differ significantly between the groups. However, adolescents with idiopathic erythrocytosis demonstrated significantly higher systolic and diastolic BP load values during 24 h, daytime, and nighttime periods when compared with healthy controls (p < 0.05). Renal tubular and glomerular function parameters were similar between groups. Hematocrit levels showed significant correlations with multiple ABPM load parameters. In the multivariable linear regression analysis, hematocrit remained independently associated with 24 h systolic BP load after adjustment for age, BMI, and serum creatinine. Conclusions: Adolescent males with idiopathic erythrocytosis exhibited increased ambulatory BP load despite similar mean BP values to controls. Elevated hematocrit may contribute to early alterations in BP regulation in adolescents with idiopathic erythrocytosis.