Mr J was an 89-year-old man with a long history of problems voiding due to increasing benign prostatic hyperplasia. He was on tamsulosin and finasteride for years when he began to experience worsening dementia. As his dementia progressed, it became necessary to move him to a long-term care facility. Aides noted that his stream was more of a slow dribble. When asked, his wife assured them that it had been that way for years. One morning, Mr J was found unconscious on the floor. He was transported to the nearest emergency department where he was found to have a K+ of 6.5 mEq/L and a creatinine of 12.1 mg/dL. A Foley catheter was inserted and 2 liters of urine returned in less than 3 hours. He was treated emergently with IV insulin in a D5 ½ NS drip and transported to a tertiary care facility. During the next few hours his lab values normalized. He continued to produce large amounts of urine amounting to nearly 8 liters in the first 24 hours. However, as his immediate status improved, it became apparent that he was producing urine far in excess of normal. Soon the staff was replacing K+ and NS to keep up with the loss.
Postobstruction diuresis (POD) can occur when retained urine is allowed to drain without periodic clamping of the catheter to allow volume and pressure sensors to adjust. POD is a rare but potentially lethal complication associated with the relief of urinary obstructions. Urine production exceeding 200 mL per hour for 2 consecutive hours or producing greater than 3 L of urine in 24 hours is diagnostic of POD. Mr J was eventually discharged back to the LTC in stable condition with a permanent Foley catheter in place.
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