What is the therapeutic approach to patients with kidney stones?
Kidney stones do not require procedural intervention unless they are associated with or are likely to cause pain, obstruction, infection, or significant bleeding. Ureteral stones may also be treated conservatively (monitored) if there is no renal failure, fever, obstruction, infection, or pain. Pain can be controlled with nonsteroidal antiinflammatory drugs, but opioid analgesics may be necessary to treat acute pain exacerbations. Stones < 5 mm in diameter pass spontaneously within 4 to 6 weeks 75% of the time, but those > 10 mm in diameter usually do not. Passage of stones ranging from 5 mm to 10 mm in diameter is variable. Medical expulsive therapy (MET) with alpha-blockers, such as tamsulosin (0.4 mg daily), the calcium channel blocker nifedipine extended release (ER) (30 mg), and the phosphodiesterase type 5 inhibitor tadalafil (10 mg daily), may increase distal ureteral stone passage 65% by reducing ureteral spasm and improving peristalsis during acute colic episodes. MET therapy usually works within 4 weeks; tamsulosin is most effective, but combination MET therapy may be more successful. Corticosteroids may improve success by decreasing ureteral inflammation. Patients with symptomatic stones, stones > 5 mm in diameter, or multiple stones should be referred for urologic evaluation. Unless contraindicated, preventing stone recurrence requires: 2 to 3 L/day of fluid to increase urine output to > 2 L/day; intake of < 2 g/day of sodium; 0.8 to 1.0 g/kg ideal body weight of protein with more plant protein (two thirds of total) and less animal protein (one third); 1000 to 1200 mg/day of dietary calcium; and avoidance of grapefruit juice, excessive calcium supplements, oxalate, and vitamin C. If insufficient calcium is available in the diet and additional calcium supplements are needed for bone health, the calcium supplements should be taken with meals for a total daily calcium (meals + supplements) of 1000 to 1200 mg/day. Consider measuring 24-hour urine calcium, with and without the calcium supplement, to determine whether the supplement causes excessive urinary calcium that may require therapeutic changes.
