From the Guidelines
Post obstructive diuresis occurs after the relief of urinary tract obstruction due to the accumulation of nitrogenous waste products, sodium, and water in the body, and the damage to renal tubules caused by increased hydrostatic pressure. The obstruction leads to an increase in production of natriuretic factors like atrial natriuretic peptide and resistance to antidiuretic hormone, which further contributes to the diuresis once the obstruction is relieved 1. When urine flow is blocked, there is an accumulation of substances in the body, and the obstruction causes damage to the renal tubules, impairing their ability to reabsorb sodium and water. The body's response to the obstruction, including increased production of natriuretic factors and resistance to antidiuretic hormone, also plays a role in the development of post obstructive diuresis. Key factors that influence the severity of post obstructive diuresis include:
- The duration of the obstruction
- The presence of bilateral obstruction or obstruction of a solitary kidney
- The degree of damage to the renal tubules Management of post obstructive diuresis involves careful monitoring of fluid status, electrolytes, and renal function, with appropriate fluid replacement to prevent dehydration and electrolyte imbalances, as seen in the management of heart failure patients with diuretic therapy 1. In some cases, diuretic resistance may occur, and can be overcome by the intravenous administration of diuretics, the use of combination diuretic therapy, or the use of diuretics together with drugs that increase renal blood flow 1. The goal of management is to prevent dehydration and electrolyte imbalances, while also eliminating fluid retention and preventing the recurrence of volume overload. This can be achieved through careful monitoring and adjustment of diuretic dosage, as well as patient education on self-monitoring of weight and fluid status. Overall, the management of post obstructive diuresis requires a comprehensive approach that takes into account the underlying physiological mechanisms and the individual patient's needs.
From the Research
Causes of Post-Obstructive Diuresis
- Post-obstructive diuresis is a polyuric response initiated by the kidneys after the relief of a substantial bladder outlet obstruction 2
- The syndrome of post-obstructive diuresis corresponds to a massive polyuria and natriuresis occurring after the drainage of an obstructive acute kidney injury 3
- Prolonged bilateral ureteral obstruction can cause severe structural and functional tubular damage, leading to post-obstructive diuresis 4
Pathophysiology
- Disordered proximal tubule function may contribute to the development of post-obstructive diuresis, leading to inappropriate losses of salt and water, and excessive urinary excretion of electrolytes 5
- Partial nephrogenic diabetes insipidus can also cause post-obstructive diuresis 4
Predictors of Post-Obstructive Diuresis
- Increased residual urine volume is an independent predictor of post-obstructive diuresis, with a residual urine volume of more than 1150 mL associated with a high probability of post-obstructive diuresis 6
- Elevated creatinine levels (>120 umol/L) are also an independent predictor of post-obstructive diuresis 6
- Other factors, such as serum urea and systolic and diastolic blood pressure, may also be correlated with post-obstructive diuresis 6
Clinical Implications
- Post-obstructive diuresis can lead to dehydration, electrolyte imbalances, and death if not adequately treated 2
- Early diagnosis and treatment of post-obstructive diuresis are crucial to prevent mortality 2
- Primary care physicians should be familiar with post-obstructive diuresis and be able to identify patients at risk, especially after relieving a urinary obstruction 2