A Relationship Between Blood Pressure Control Hematocrit Level and Renal Function in Treated Essential Hypertension

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The effect of rigid blood pressure control on renal function is an unsettled issue. This study describes a retrospective analysis on the relationships between blood pressure control, hematocrit levels, and renal function in 97 treated hypertensive patients. Data analysis was done on systolic and diastolic blood pressure, hematocrit levels, renal function assessed by serum urea nitrogen (SUN), serum creatinine (Scr), and hydrochlorothiazide (HCTZ) dose at entry and at four anniversary dates thereafter. The patients were divided into two groups: group I and group II on the basis of HCTZ dose. Group I received an average of 100 mg HCTZ daily, whereas group II received an average of 50 mg HCTZ daily. In group I, the decrement in both systolic and diastolic blood pressure over time was highly significant (P < .0001); however, no change in renal function was noted. In group II, systolic blood pressure decreased significantly (P < .01) from entry to year 1, then leveled off. In year 4, systolic blood pressure was not different from that of entry. Conversely, the difference between entry and year 4 diastolic blood pressure was highly significant (P < .0001). In group II, significant decreases were noted between entry and year 4, SUN (16.5 ± 5.7 versus 14.9 ± 4.1 mg/dL; P < .0012) and Scr (1.29 ± .23 versus 1.24 ± .19 mg/dL; P < .0192). Hematocrit showed diverse responses; in group I, hematocrit significantly increased from entry to year 4 (44.8 ± 2.5 versus 47.2 ± 3.9%; P < .01); whereas, in group II, hematocrit significantly decreased (47.7 ± 3.8 versus 44.9 ± 3.4%; P < .001). A separate analysis between blacks and whites showed that black patients did better with high‐dose (very high dose according to current concept) of HCTZ in both blood pressure and renal function controls, whereas white subjects tend to do better with low‐dose (high dose according to current concepts) of HCTZ. This study concludes that high‐dose (or very high dose) HCTZ is beneficial for black hypertensives, however, low‐dose (or high‐dose) HCTZ appears to be universally beneficial.



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