Biochemical and body composition analysis of nocturia in the elderly.

Aims: Nocturia is a common symptom in the elderly, and various contributing factors have been suggested. Therefore, in order to investigate which factors are strongly related to occurrence of nocturia, we performed a suite of examinations.

Methods: One hundred eighty volunteers were divided into three groups: a young adult control group (60 healthy persons without nocturia), an elderly control group (60 healthy persons with a low mean frequency of nocturnal urination, i.e.,
Results: The features specific to the elderly nocturia group are as follows: (1) a decrease of the nighttime plasma melatonin level, (2) an increase of nighttime plasma catecholamine levels, (3) an increase of daytime and nighttime plasma natriuretic peptide levels, (4) an increase of blood pressure, (5) a decrease of daytime and nighttime urinary osmotic pressure, (6) an increase of total urine volume, and (7) an increase of the edema ratio before sleeping.

Conclusions: These results suggest that sleep disturbance, hypertension, and excessive fluid intake are major factors contributing to an increased frequency of nocturnal urination (>twice per night) in the elderly.