From the Guidelines
Mannitol and furosemide are not effective for expelling obstructing kidney stones. While these diuretics can increase urine flow, they do not generate sufficient pressure to physically push out established kidney stones. Mannitol works as an osmotic diuretic that draws water into the tubules, while furosemide is a loop diuretic that blocks sodium reabsorption in the kidneys. Neither medication creates the focused, directional pressure needed to expel stones.
According to the 2007 guideline for the management of ureteral calculi 1, medical expulsive therapy (MET) is a more effective approach, which involves the administration of drugs to facilitate stone passage. The guideline suggests that alpha-blockers, such as tamsulosin, are the preferred agents for MET, as they have been shown to facilitate ureteral stone passage by relaxing ureteral smooth muscle.
Some key points to consider when using MET include:
- Alpha-blockers, like tamsulosin (0.4mg daily), can relax ureter muscles and facilitate stone passage 1
- Calcium channel blockers, like nifedipine (30mg daily), may also be used to reduce spasms and facilitate stone passage 1
- Adequate hydration (2-3 liters of water daily) is essential to help flush out the stones
- Pain management with NSAIDs or opioids as needed, and sometimes antiemetics for nausea, is also important
It's worth noting that the effectiveness of MET may vary depending on the size and location of the stone, as well as the individual patient's response to treatment. However, for stones smaller than 10mm, MET is often the first line of treatment. Larger stones or those causing severe obstruction, infection, or intractable pain typically require urological intervention such as extracorporeal shock wave lithotripsy, ureteroscopy, or percutaneous nephrolithotomy rather than medication-based expulsion.
From the Research
Medical Expulsive Therapy for Kidney Stones
- Medical expulsive therapy (MET) has been shown to facilitate the passage of kidney stones, with alpha-blockers and calcium channel blockers being commonly used 2.
- These medications have been found to increase stone expulsion rates and reduce colic events, with a higher and faster expulsion rate compared to a control group 2.
- However, there is no direct evidence to suggest that mannitol and furosemide can produce enough pressure in the kidneys and ureters to expel obstructing kidney stones.
Treatment Options for Nephrolithiasis
- Observation, medical expulsive therapy, extracorporeal shock wave lithotripsy (ESWL), ureteroscopy, and percutaneous nephrolithotomy are all treatment options for nephrolithiasis 3, 4, 5.
- The choice of treatment depends on the size and location of the stone, as well as the patient's symptoms and medical history.
- Medical expulsive therapy with an alpha blocker may be beneficial for passage of ureteral stones in children 3.
Management of Kidney Stones
- The management of kidney stones involves pain control, medical expulsive therapy, and follow-up imaging to monitor stone position and assess for hydronephrosis 5.
- Asymptomatic kidney stones should be followed with serial imaging, and should be removed in case of growth, symptoms, urinary obstruction, recurrent infections, or lack of access to health care 5.
- Lifestyle modifications such as increased fluid intake should be recommended for all patients, and thiazide diuretics, allopurinol, or citrates should be prescribed for patients with recurrent calcium stones 5.
Use of Mannitol and Furosemide
- There is no evidence to suggest that mannitol and furosemide are used to produce pressure in the kidneys and ureters to expel obstructing kidney stones 2, 3, 6, 4, 5.
- Mannitol and furosemide are diuretics that are used to increase urine production, but their use in the treatment of kidney stones is not well established.