Introduction
Nocturia is a common condition especially in aging population and is
defined as the complaint of waking at night one or more times to
void.1 The definition has been recently updated as to
sleep or intent to sleep after each voiding period which should be
demonstrated by a bladder diary.2 There is growing
evidence in the last decade that nocturia is not only a part of diseases
affecting the lower urinary tract such as benign prostatic hyperplasia
(BPH) and overactive bladder (OAB), but a distinct entity which may
arise from several other medical conditions.3 One of
the possible mechanisms mostly included is nocturnal polyuria (NP)
defined as the excessive urine production at night while asleep;
> 33% of the 24-hour urine production in patients
>65 years and > 20% of the 24-hour urine
production in younger patients.4 Global polyuria
(24-hour urine volume > 40 ml/kg), reduced bladder capacity
due to lower urinary tract dysfunction and primary / secondary sleep
disorders constitute the other mechanisms. These different mechanisms
need to be explored in all patients presenting with nocturia in order to
provide the best treatment approach. However, it is not always possible
or easy to obtain a detailed bladder diary in daily clinical practice
which is essential for differentiating between afore-mentioned various
pathophysiological mechanisms.
Nocturia has negative impacts on quality of life (QoL) of patients and
these impacts are mostly related with the severity of nocturia. Some of
the studies concluded that two or more nocturia episodes lead to bother
from nocturia and the degree of bother was associated with severity of
nocturia.5,6 However there is no consensus on nocturia
severity and its impact on QoL of patients and there are few studies in
the existing literature evaluating the mechanisms of nocturia. So, we
aimed to identify pathophysiological mechanisms of nocturia and seek
whether proposal of nocturia grading helps for differentiation of the
various pathologic conditions.