A RELATIONSHIP BETWEEN BLOOD-PRESSURE CONTROL, HEMATOCRIT LEVEL, AND RENAL-FUNCTION IN TREATED ESSENTIAL-HYPERTENSION

The effect of rigid blood pressure control on renal function is an uns ettled issue. This study describes a retrospective analysis on the rel ationships between blood pressure control, hematocrit levels, and rena l function in 97 treated hypertensive patients. Data analysis was done on systolic and diastolic blood pressure, hematocrit levels, renal fu nction assessed by serum urea nitrogen (SUN), serum creatinine (Scr), and hydrochlorothiazide (HCTZ) dose at entry and at four anniversary d ates thereafter. The patients were divided into two groups: group I an d group II on the basis of HCTZ dose. Group I received an average of 1 00 mg HCTZ daily, whereas group II received an average of 50 mg HCTZ d aily. In group I, the decrement in both systolic and diastolic blood p ressure over time was highly significant (P < .0001); however, no chan ge in renal function was noted. In group II, systolic blood pressure d ecreased significantly (P < .01) from entry to year 1, then leveled of f. In year 4, systolic blood pressure was not different from that of e ntry. Conversely, the difference between entry and year 4 diastolic bl ood pressure was highly significant (P < .0001). In group II, signific ant decreases were noted between entry and year 4, SUN (16.5 +/- 5.7 v ersus 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 gr oup 1, hematocrit significantly increased from entry to year 4 (44.8 /- 2.5 versus 47.2 +/- 3.9%; P < .01); whereas, in group II, hematocri t significantly decreased (47.7 +/- 3.8 versus 44.9 +/- 3.4%; P < .001 ). A separate analysis between blacks and whites showed that black pat ients did better with high-dose (very high dose according to current c oncept) of HCTZ in both blood pressure and renal function controls, wh ereas white subjects tend to do better with low-dose (high dose accord ing to current concepts) of HCTZ. This study concludes that high-dose (or very high dose) HCTZ is beneficial for black hypertensives, howeve r, low-dose (or high-dose) HCTZ appears to be universally beneficial.