From the Guidelines
A urine pH of 8.5 is not recommended for patients at risk of tumor lysis syndrome, as it may lead to xanthine crystal precipitation in renal tubules, potentially resulting in xanthine-obstructive uropathies. This is based on the findings of a study published in the Journal of Clinical Oncology in 2008 1. The study suggests that alkaline urine does not substantially increase the solubility of xanthine and hypoxanthine, and may even lead to complications such as metabolic alkalosis and calcium phosphate precipitation.
Key Considerations
- The solubility of uric acid increases with increasing pH, but this does not apply to xanthine and hypoxanthine, which have low solubility even at higher pH levels 1
- Increasing urine flow rate is a more effective strategy for preventing urate-induced obstructive uropathy than alkalinization 1
- The use of sodium bicarbonate to alkalinize the urine is not recommended for the prevention and treatment of tumor lysis syndrome, due to the potential complications associated with alkalinization 1
Recommendations
- Patients at risk of tumor lysis syndrome should aim for a urine pH within the normal range of 4.5-8.0 to minimize the risk of xanthine crystal precipitation
- Increasing fluid intake can help to flush the urinary system and reduce the risk of uric acid crystallization 1
- Further evaluation with urinalysis and urine culture may be necessary to rule out underlying infections or metabolic conditions that may be contributing to the alkaline urine pH.
From the Research
Urine pH of 8.5
- A urine pH of 8.5 is considered alkaline, which can be associated with certain types of urinary tract infections (UTIs) 2.
- The Proteeae group, which includes Proteus species, Morganella morganii, and Providencia species, can produce urease, leading to an increase in urine pH 2, 3.
- Studies have shown that urine cultures growing the Proteeae group are associated with significantly more alkaline urine than other bacteriuria cultures 2.
- Nitrofurantoin resistance is more common in alkaline urine, with a significant decrease in susceptibility at urine pH 8-9 and 9 2.
- Other antibiotics, such as amoxicillin-clavulanate, may be more effective in treating UTIs with alkaline urine 2, 4.
Antibiotic Resistance
- The increasing rate of antibiotic resistance in uropathogens is a concern, with many strains showing multidrug resistance 5, 4, 6.
- ESBL-producing uropathogens, such as Klebsiella spp., Proteus mirabilis, and Enterobacter cloacae, are often resistant to multiple antibiotics 5, 6.
- The use of antibiotics such as ciprofloxacin and trimethoprim-sulfamethoxazole may be limited due to high rates of resistance 5, 4.
Treatment Options
- The choice of antibiotic for treating UTIs should be based on local susceptibility patterns and the specific type of uropathogen involved 5, 4.
- Nitrofurantoin, amoxicillin-clavulanate, and sulfamethoxazole-trimethoprim may be effective options for treating UTIs, but their use should be guided by susceptibility testing 5, 2, 4.
- In cases of multidrug-resistant uropathogens, alternative antibiotics such as carbapenems, ceftazidime-avibactam, and fosfomycin may be necessary 5, 6.