Is There Any Relationship between Upper Urinary Tract Stone Development and Sleep Posture?

Kim, Yong Jun; Kim, Min Eui; Lee, Nam Kyu

Abstract

PURPOSE: Recurrent stone formers are usually presented with calculi on the ipsilateral side. It has been postulated that sleep posture may alter renal hemodynamics and urinary flow during sleep and promote stone formation. We investigated the correlation of sleep posture with unilateral stone formation and the influence of body position on renal hemodynamics and urinary flow.
MATERIALS AND METHODS
We prospectively evaluated the sleep posture of 106 patients with unilateral urolithiasis. A questionnaire was used to evaluate sleep posture of the patients. Sixteen normal volunteers were studied. They were evaluated in the supine, left and right lateral decubitus positions with separate diuretic renograms spaced one week apart. Renal scans were obtained using diethylenetriamine-pentaacetic acid (99mTc- DTPA) after the patient was equilibrated in the specific body position for 30 minutes.
RESULTS
Of the patients, 66 slept consistently with 1 side in a dependent position, and the side of the stone was identical to the dependent sleep side in 80.2% (p<0.01). Renal perfusion and the T1/2 for clearances in the dependent kidney in the left and right decubitus positions were significantly increased when compared to the same kidney in the supine position (p<0.01).
CONCLUSIONS
Specific sleeping position has significant effects on renal perfusion and urinary flow as measured by nuclear renal scintigraphy. This finding may help explain the correlation of sleep posture with unilateral urolithiasis. Even though this observation needs further investigation, it should be factored into the evaluation and prevention of unilateral stone disease.