1. The effects of posture and exercise on the relationship between low-level urinary albumin excretion (microalbuminuria) and blood pressure was investigated in two groups of non-diabetic patients at increased cardiovascular risk: 21 otherwise healthy patients with untreated essential hypertension (blood pressure > 160/90 mmHg), and 14 age-matched patients with blood pressure at presentation within the normotensive range (< 160/90 mmHg) attending a cardiovascular clinic for assessment of chest pain.
2. A significant linear relationship between logarithmically transformed ‘spot’ urinary albumin/creatinine ratio and simultaneous clinic blood pressure existed when data from both groups of patients were analysed (r = 0.58, P < 0.05). The relationship between the scatter plot of blood pressure and the albumin/creatinine ratio appeared most marked when the mean blood pressure exceeded 120 mmHg.
3. In patients with essential hypertension, clinic systolic blood pressure was related to the albumin/creatinine ratio in simultaneous ‘spot’ urine samples (r = 0.69, P < 0.05) and also to the albumin/creatinine ratio in early-morning urine samples (r = 0.51, P < 0.05). However, the relationship between clinic blood pressure and simultaneous ‘spot’ urinary albumin/creatinine ratio in the patients with chest pain did not achieve significance when analysed independently.
4. Hourly averaged ambulatory intra-arterial blood pressure was recorded in four of the patients with essential hypertension during normal daytime activity, and a significant correlation with the simultaneous hourly daytime urinary albumin/creatinine ratio was found (r = 0.65, P < 0.01).
5. Low-level albumin excretion increased in both groups after exercise: peak systolic blood pressure during exercise was related to the rise in albumin excretion (hypertensive patients, r = 0.68, P < 0.01; normotensive patients, r = 0.66, P < 0.05).