Volume-dependent hypertension is an increase in blood pressure due to volume overload in some patients. A short-term intensive diuretic therapy test can be used to determine if the hypertension is volume-dependent. Excessive dietary sodium intake can counteract the effects of antihypertensive medications, and volume overload is often present in cases of obesity, diabetes, renal impairment, and chronic renal insufficiency. In some patients treated with combination therapy for hypertension, the failure to effectively control blood pressure is often found to be due to the absence of diuretics or inappropriate choice and dose of diuretics, and the combination of a long-acting thiazide diuretic and a short-acting tab diuretic to observe the therapeutic effect.