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Medical Acute Stone Care
Editorial by the Selection committee member for the Kidney Stones Bracket:
David S. Goldfarb, MD
Professor, Chief of Nephrology at NY Harbor VA Medical Center
Clinical Chief of Nephrology, Department of Medicine and Neuroscience and Physiology,
New York University Langone Medical Center
Dr. Goldfarb is the Chief of Nephrology at the New York Harbor VA Medical Center and the Clinical Chief of Nephrology at the New York University Langone Medical Center. He has a long-standing interest in kidney stone pathophysiology. His group established a registry of patients with cystinuria. The goal of this registry is to follow patients with cystinuria and learn more about the course of this disorder. He also is involved in new drug development for the treatment of cystinuria. The consortium also studies Dent disease, primary hyperoxaluria and APRT deficiency (a cause of dihydroxyadenine stones). Dr. Goldfarb is the associate editor of the Clinical Journal of the American Society of Nephrology (CJASN) and the founding editor of CJASN‘s eJournal Club.
Medical stone care, also known as “Medical Expulsive Therapy”, MET, continues to be a commonly practiced therapy.
A common misperception is the use of forced diuresis. It’s usual ER therapy and unlikely to ever have any benefit. If a patient with an obstructed kidney is given intravenous saline, the saline will be excreted by the contralateral kidney, the one that still has a GFR. It will NOT get to the obstructed kidney which quickly experiences a reduction in GFR. The best RCT on this subject was done by Preminger’s group at Duke.They gave patients with obstructed stones 2L NS over 2h, vs. 20 mL over 2h. There was no benefit of the aggressive fluid therapy in pain scores or stone passage rates. So we need additional therapies to promote stone passage.
Alpha blockers appear to be effective in numerous relatively small, if perhaps non-definitive RCTs. Presumably they cause ureteral relaxation and can be effective for stones up to 1 cm in size and even in a proximal location. I usually prescribe tamsulosin 0.4 mg qhs for 28 days assuming the patient does not have the sort of pain that requires hospitalization, and they can go to work or school or whatever. I warn them about hypotension, especially in younger women who have relatively low BP to begin with.
I also usually recommend some OTC NSAID (e.g., Aleve = naproxen 220 mg tabs, 2 tabs bid) since that adds some anti-inflammatory effect which might facilitate stone passage by reducing ureteral edema. Occasionally, in the NSAID-intolerant patient, I prescribe prednisone 20 mg qd instead.
Most of the European studies of calcium channel blockers, e.g., nifedipine, showed efficacy, and included concomitant administration of glucocorticoids, but whether these are independently useful has not been determined.
I also recommend for renal colic getting into a warm bath, turning down the lights and drinking some beer for maximal relaxation/dilatation; something like a Goose Island Lolita.
The first time I prescribed an alpha-blocker for a woman named Jackie was a memorable experience. At that time I was practicing at St. Vincents Hospital in New York, now closed. I called in the prescription and the pharmacist said “um, doc, Jackie does not have a prostate gland”. I replied, “I’m practicing here in Greenwich Village and YOU don’t know whether Jackie has a prostate gland or not!”