Lower Systolic Blood Pressure in 67 Boys With Klinefelter Syndrome Compared to 1842 Healthy Danish Boys

Objective Our objective was to develop age‐ and height‐specific reference ranges for blood pressure, pulse pressure and mean arterial pressure in healthy boys and to compare these to measurements in patients with Klinefelter syndrome followed longitudinally through childhood and adolescence. Design Cohort study consisting of a population‐based reference cohort including 1842 healthy non‐obese boys aged 0–20 years and 67 patients with Klinefelter syndrome aged 7–20 years, followed at a single tertiary center. Methods Height, weight, and blood pressure were measured, and references were developed as a function of age, height, and their combined effect in healthy boys. In patients with Klinefelter syndrome standard deviation scores were calculated for systolic and diastolic blood pressure, pulse pressure and mean arterial pressure. These were adjusted for age and height independently, as well as combined age and height. A subgroup analysis in patients with Klinefelter syndrome assessed whether testosterone replacement therapy influenced blood pressure. Results Systolic and diastolic blood pressure increased with increasing age in healthy boys. Patients with Klinefelter syndrome had significantly lower systolic blood pressure compared to the healthy, non‐obese reference population, with a mean standard deviation score of –0.65, –0.90, –0.91 when adjusted for age, height, and both, respectively. Diastolic blood pressure did not differ from controls. Pulse pressure showed a mean standard deviation score of –0.74, –0.99, and –0.94 when adjusting for age, height or both, respectively. Mean arterial pressure showed a mean standard deviation score of –0.27, –0.33, and –0.41 adjusted for age, height or both, respectively. Testosterone replacement therapy had no significant effect on blood pressure. Conclusions Our study showed that patients with Klinefelter syndrome have lower systolic but similar diastolic blood pressure compared to our new blood pressure reference ranges. Pulse pressure and mean arterial pressure were both significantly lower after any adjustment compared to healthy controls.